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Dietary Supplements Nursing CE Course

2.5 ANCC Contact Hours

About this course:

This activity aims to provide an overview of the various dietary supplements, including the potential benefits, risks, and adverse effects that can occur when utilizing these products.

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Dietary Supplements 

Disclosure Statement

This activity aims to provide an overview of the various dietary supplements, including the potential benefits, risks, and adverse effects that can occur when utilizing these products.

Upon completion of this module, learners will be able to:

  • outline the history and regulatory process of dietary supplements
  • discuss the current recommendations for dietary intake of various nutrients
  • explore the most common categories of nutritional supplements
  • describe the benefits of amino-based dietary supplements
  • consider the implications of the use of herbal supplements
  • explain the therapeutic use of probiotic supplements
  • summarize the potential benefits of fish oil supplements

Various terms refer to the types of dietary supplements available based on what they contain. Examples include:

  • Amino acids are the building blocks of life, a class of organic compounds that combine to form proteins; there are 20 identified amino acids, 9 of which are considered essential amino acids. The body cannot synthesize these, and they must be obtained through dietary intake (Bhupathiraju & Hu, 2023).
  • Antioxidants are artificial or natural substances that can protect cells from the damaging effects of free radicals. They are found in fruits and vegetables or as dietary supplements; examples include beta-carotene, lycopene, and vitamins A, C, and E (National Cancer Institute [NCI], n.d.).
  • Dietary supplements are vitamins, minerals, herbs, amino acids, and other products added to the diet. Dietary supplements are usually taken orally as powders, pills, capsules, drinks, or energy bars (NCI, n.d.).
  • Fat-soluble vitamins do not dissolve in water, are most abundant in high-fat foods, and are better absorbed into circulation when eaten with fat. Fat-soluble vitamins include vitamins A (retinol), D (cholecalciferol and ergocalciferol), E (alpha-tocopherol), and K (phylloquinone and menaquinone). Only vitamins A and E are stored in the body; the others must be regularly consumed (Bhupathiraju & Hu, 2023; NCI, n.d.).
  • Macronutrients are essential nutrients, including protein, carbohydrates, fat, and water, that the body requires in large quantities (Bhupathiraju & Hu, 2023).
  • Micronutrients are essential nutrients needed in minute amounts, such as vitamins, minerals, trace elements, and antioxidants (Bhupathiraju & Hu, 2023; McCance & Huether, 2019).
  • Water-soluble vitamins dissolve in water, are not stored by the body, and must be continuously replenished via diet or dietary supplements. Any excess vitamin is excreted. All B vitamins and vitamin C are water-soluble. Vitamin B12 is an exception; it is a water-soluble vitamin that can be stored in the liver for an extended period (Bhupathiraju & Hu, 2023).



Our current knowledge of dietary supplements has evolved significantly over the past hundred years; however, since 400 BC, the link between food and health has been known. See Table 1 for a brief overview of the history of dietary supplements.


Table 1

Dietary Supplement History


Significant Event

400 BC

Hippocrates, “The Father of Medicine,” notes, "Let thy food be thy medicine and thy medicine be thy food.”


Leonardo da Vinci equates the process of metabolism to a burning candle.


Dr. James Lind performs the first nutritional experiment and identifies scurvy’s cause of vitamin C deficiency.


Elements of food identified: carbon, hydrogen, oxygen, and nitrogen.


Justus Liebig discovers the chemical makeup of carbohydrates (sugar), proteins (amino acids), and fats (fatty acids).


Christiaan Eijkman discovers the cause of beriberi-vitamin B1 (thiamine).


E.V. McCollum discovers the first fat-soluble vitamin-vitamin A.


Dr. Casimir Funk coins the term vitamin as necessary in dietary intake.


William Rose discovers essential amino acids.


Water-soluble vitamins B and C were identified.


The role of vitamins and minerals as components of enzymes and hormones in the body was established.


Linus Pauling proposes that giving the body proper molecules at the appropriate concentration could help achieve a prolonged and healthier life. The term “optimum nutrition” comes from his studies.

Mid-20th century

All major vitamins are identified and produced. Recommended Daily Allowances (RDAs) are determined by the US, British Medical Associations, and the League of Nations. Standards for nutritional research and recommendations are established during this time, focusing on single nutrients linked to specific disease states. This knowledge leads to fortifying common and readily available foods with needed vitamins such as iodine in salt to decrease the risk of goiter or adding niacin (vitamin B3) and iron to wheat flour and bread. Fortifying food is commonplace in the US and equally common around the world.


Malnutrition and vitamin deficiencies significantly decline but diet-related non-communicable diseases such as cardiovascular disease (CVD), obesity, and type 2 diabetes (T2D) increase. This leads to focusing on micronutrients and supplements for pregnant women and children.

 (Kantor et al., 2016; National Institutes of Health [NIH], n.d.-c.; Mozaffarian et al., 2018; Smith, 2004; Swan, 2015; United States Department of Agriculture [USDA], 2020; Venkatraman & Dandekar, 2015)

Over the past century, 13 essential vitamins have been identified. The term essential indicates that they must be ingested to maintain health and function. The human body will not function properly in their absence, and nutritional diseases will develop. Beyond the 13 essential vitamins, dietary supplements are not well defined. Manufacturers take great liberty in developing a broad range of dietary supplem

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ents, and there is little scientific proof of necessity or outcome with their intake. On average, over $163.9 billion is spent on nutritional supplements globally; this is expected to increase to $327.4 billion by 2030. With this number of products in use, consistency, quality, and safety are of primary concern to most (Grand View Research, n.d.; NIH, 2023a).


Regulatory Process

Dietary supplement regulation began in 1906 with the passing of the Pure Food and Drug Act. This act was an effort by the federal government to emphasize the safety and accuracy of marketed products. This was in response to the growing prevalence of unsafe food and medication and the increase in fraud regarding the efficacy of remedies. During the 1900s to 1920s, more information was discovered regarding food elements responsible for various aspects of health and nutrition. The role of upholding the rules and punishing violators was given to the US Food and Drug Association (FDA). In 1938, in response to the sulfanilamide scandal that resulted in 107 deaths, the Federal Food, Drug, and Cosmetic Act was passed, making the 1906 regulations obsolete (Natural Products Association [NPA], n.d.).

In 1994, the US Congress unanimously passed the Dietary Supplement Health and Education Act (DSHEA), which defined the term dietary supplement as a product that supplements the diet under the category of food (rather than medication). The DSHEA also outlined the types of ingredients that could be used in dietary supplements and that they must contain one or more ingredients or their constituents (components, parts, or ingredients of a larger whole). This act also prohibited manufacturers and distributors from marketing adultered or misbranded products. According to the DSHEA, supplements are to be taken orally (by mouth) as a capsule, pill, tablet, or liquid and should be labeled on the front panel as a dietary supplement. Products can range from children's vitamins to sports nutrition or weight-loss products for adults (FDA, 2023; NPA, n.d.).

The DSHEA provides the FDA with the regulatory authority and ability to enforce processes that ensure consumer access to quality dietary supplements. However, the FDA regulations regarding dietary supplements are much less stringent than other food and drug products. Manufacturers do not have to prove that dietary supplements are safe and effective through testing or clinical trials before marketing as other drugs are required to do; instead, the FDA simply requires that a dietary supplement is proven safe. The DSHEA also gave the FDA the power to develop manufacturing guidelines for dietary supplements. In 2007, the FDA mandated that dietary supplements be produced in compliance with current Good Manufacturing Practices (GMPs) to help ensure their quality, purity, strength, and composition. As a result, the FDA can remove potentially unsafe products from the market (NIH, 2023a; NPA, n.d.).

When a manufacturer develops a new product, they only have to notify the FDA if it contains a new dietary ingredient (NDI) not on the market before October 15, 1994. There is no definitive list of dietary ingredients in dietary supplements before 1994, but manufacturers and distributors are expected to determine all ingredients in their supplements and ensure compliance. In the event of an NDI, the manufacturer must submit an NDI dossier to notify the FDA and provide a rationale as to why the manufacturer feels it is appropriate to add the ingredient, a description of the ingredient, and any identifying published materials that are available (NPA, n.d.).

Dietary supplements with false or misleading labeling are considered misbranded foods (FDA, 2023). Misbranding provisions are applied if the label does any of the following:

  • fails to list each ingredient’s name and quantity
  • fails to identify the product as a dietary supplement
  • fails to state from which plant each ingredient is derived
  • makes claims that the supplement is a cure for a particular disease
  • fails to include a statement that health claims have not been evaluated by the FDA (FDA, 2023; NIH, 2023a)

Dietary supplements may have claims of health, nutrition, and function. Each type of claim has implications based on FDA expectations. For example, health claims may describe a relationship between a food or dietary supplement ingredient and a reduced disease or health-related condition risk. A nutrient content claim describes the amount of a nutrient or dietary substance in a product. A structure or function claim explains how the product may affect a body system or organ (i.e., the cardiovascular system or the liver). If a structure or function claim is made, the manufacturer must notify the FDA with the text of the claim and the results of at least two randomized controlled clinical trials at least 30 days before the product is put on the market for sale (NPA, n.d.). The manufacturer must also add a disclaimer to any health-related claim that it “has not been evaluated by the FDA” and “is not intended to diagnose, treat, cure, or prevent any disease" (NIH, 2023a, para. 17).

In 1985, The US Department of Health and Human Services (HHS) and the USDA jointly formed the Dietary Guidelines Advisory Committee (DGAC). This committee evaluates dietary guidelines, identifying common healthy diet characteristics, identifying new research, and developing food-based recommendations critical to good health every 5 years. The most recent report from the DGAC was released in 2020. This report found that over 70% of Americans were classified as overweight or obese. This number has been increasing over the past two decades, and the prevalence of children that are overweight or obese is of particular concern. The prevalence of obesity has contributed to several diet-related chronic conditions such as type 2 diabetes and CVD. It is estimated that 6 out of 10 Americans have one chronic illness, and 4 out of 10 have at least two chronic illnesses. The report also found that food insecurity is a contributing problem for 37 million individuals, including 6 million children in the US who live in food-insecure households (DGAC, 2020).

The report notes that positive changes to dietary habits can affect individual outcomes related to preventable disease progression. While this report primarily focuses on good nutrition through a healthy diet, the value and limitations of dietary supplements are also discussed. Nutritional supplements are typically utilized for wellness rather than disease management; however, there is recognized value to supplementation in some disease processes. Therefore, healthcare professionals (HCPs) are advised to discuss dietary supplements with their patients to determine the best supplemental regime for each individual. Approximately 61% of 18-34-year-olds, 74% of 35-54-year-olds, and 81% of individuals older than 55 take dietary supplements (DGAC, 2020; Mikulic, 2022).

Current Recommendations

The Food and Nutrition Board (FNB) was established in 1940 as a component of the Health and Medicine Division of the National Academies of Sciences, Engineering, and Medicine (NASEM). The FNB is tasked with managing food safety and quality issues; establishing guidelines for adequate dietary intake by individuals; and giving authoritative judgments on the relationship between food intake, nutrition, and overall health maintenance and disease prevention (NASEM, n.d.).

Dietary reference intake (DRI) is a general term for a set of reference values used to plan and assess the nutrient intake of healthy individuals. DRIs can also be used to develop optimal diet plans and dietary supplement options (DGAC, 2020). The values often differ based on age, gender, and whether an individual is pregnant or lactating, but include:

  • recommended daily allowance (RDA): the average daily intake deemed sufficient to meet the nutritional requirements of most healthy individuals
  • adequate intake (AI): the quantity assumed to ensure adequate nutrition (this is used when the evidence is insufficient to determine an RDA)
  • percent of the daily value (DV): similar to the RDA and AI for a particular nutrient; developed by the FDA to inform consumers how much of a specific nutrient is present in a serving of food or supplement in relation to the RDA or AI; included on labels as a percentage (%DV)
  • tolerable upper intake level (UL): the maximum daily intake unlikely to cause harmful health effects (Johnson, 2022b; NIH, n.d.-b)

HCPS must remember that good nutrition is the foundation of good health, and nutritional assessments and education are vital to assisting patients in maintaining or achieving optimal health and wellness. Dietary supplements are widely marketed directly to the consumer and have a variety of ingredients intended to provide multiple benefits for health and wellness (NIH, n.d.-b).


Common Categories of Dietary Supplements

For this module, dietary supplements discussed are limited to those characterized by the NIH Office of Dietary Health, including a broad overview of vitamins, minerals, herbs/botanicals, amino acids, probiotics, and fish oil products. If additional details are sought, the NIH Office of Dietary Health offers in-depth individual educational resources and fact sheets on its website (NIH, n.d.-a).



As previously noted, there are 13 vitamins needed by the body for normal growth, health, and wellness. These vitamins are vitamin A, B vitamins (thiamine, niacin, riboflavin, biotin, pantothenic acid, vitamin B6, vitamin B12, and folate), vitamin C, vitamin D, vitamin E, and vitamin K. Most of these vitamins are obtained from dietary intake. Each vitamin has a unique function within the body, and low or high levels can lead to health problems (Johnson, 2022b). See Table 2 for the 13 essential vitamins, their potential benefits, and nursing implications; Table 3 contains these vitamins' RDAs (or AIs).


Table 2

Essential Vitamins

Dietary Supplement and Potential Benefits

Nursing Implications/Alerts

Vitamin A is a fat-soluble vitamin needed for immune function, fetal development, formation of rhodopsin (pigment in the retina), glycoprotein synthesis, and cell growth support.

Vitamin A deficiency may present with/lead to:

  • perifollicular hyperkeratosis (scaly skin), night blindness, poor growth in children, and increased risk of infection

At-risk groups for deficiency:

  • individuals with Crohn's disease, cystic fibrosis, liver disease, or alcohol use disorder (AUD)
  • premature infants

Signs of toxicity:

  • headaches
  • peeling skin
  • bone thickening
  • intracranial hypertension (Johnson, 2022b; NIH, 2022m)

Thiamine (vitamin B1) is a water-soluble vitamin involved in the flow of electrolytes into and out of muscle and nerve cells; it is needed for carbohydrate, fat, amino acid, and glucose metabolism, and central and peripheral nerve and myocardial function.

Early signs of thiamine deficiency may include:

  • loss of appetite, fatigue, irritability, reduced or absent reflexes, tingling sensation in the extremities, muscle weakness, blurry vision, nausea or vomiting, arrhythmias, shortness of breath, or delirium (particularly in older adults)

Deficiency can lead to:

  • Beriberi (peripheral neuropathy)
  • Wernicke-Korsakoff syndrome (primarily in the presence of AUD)

At-risk groups for deficiency:

  • patients with AUD, diabetes, or HIV/AIDS
  • older adults
  • bariatric surgery history

Thiamine supplementation can interact with the following:

  • chemotherapy with 5-fluorouracil (Adrucil)
  • furosemide (Lasix)
  • phenytoin (Dilantin; Johnson, 2022b; NIH, 2023c)

Riboflavin (vitamin B2) is a water-soluble vitamin that helps the body break down carbohydrates, proteins, and fats to produce energy and allows oxygen to be used by the body.

Riboflavin deficiency symptoms may include:

  • endocrine abnormalities such as thyroid deficiency, skin disorders, hyperemia (excess blood), edema of mouth and throat, angular stomatitis (lesions at corners of the mouth), cheilosis (swollen, cracked lips), hair loss, infertility, sore throat, itchy eyes, or hepatic failure
  • anemia and cataracts can occur with prolonged and severe deficiency

At-risk groups for deficiency:

  • those on a vegetarian or vegan diet with little or no milk intake
  • athletes
  • pregnant or lactating women and their infants
  • individuals with Infantile Brown-Vialetto-Van Laere or Fazio-Londe syndrome (Johnson, 2022b; NIH, 2022l)

Niacin (vitamin B3) is a water-soluble vitamin needed for carbohydrate and cell metabolism that affects the digestive, skin, and nervous systems.

Deficiency of niacin may present with/lead to:

  • pellagra (pigmented rash or brown discoloration of skin exposed to sunlight), irritated or red skin, headaches, fatigue, anxiety or depression, inability to concentrate, dizziness, poor circulation
  • increased risk of cancer in women

Drug interactions include:

  • isoniazid, and pyrazinamide (Rifater)
  • antidiabetic medications

At-risk populations for deficiency include:

  • individuals with anorexia, HIV/AIDS, AUD, inflammatory bowel disease (IBD), liver cirrhosis, Hartnup disease, or carcinoid syndrome (Johnson, 2020b; NIH, 2022j)

Pantothenic acid (vitamin B5) is a water-soluble vitamin necessary for blood cell production and helpful for converting food into energy.

Deficiency of pantothenic acid may present with/lead to:

  • numbness and burning of the hands and feet, headache, fatigue, irritability, restlessness, disturbed sleep, gastrointestinal (GI) disturbances with anorexia, hyperlipidemia

At-risk populations for deficiency:

  • individuals with pantothenate kinase-associated neurodegeneration-2 mutation (PKAN; NIH, 2021c)
  • Pyridoxine (vitamin B6) is a water-soluble vitamin that plays a role in nucleic acid biosynthesis and the metabolism of fatty acids, lipids, nitrogen, and amino acids.

Pyridoxine deficiency may present with/lead to:

  • microcytic anemia, electroencephalographic (EEG) abnormalities, dermatitis with cheilosis, glossitis (swollen tongue), depression, confusion, or weakened immune function
  • deficiency in infants can cause irritability, abnormally acute hearing, and convulsive seizures

Medication interactions include:

  • cycloserine (Seromycin)
  • valproic acid (Depakene)
  • carbamazepine (Tegretol)
  • phenytoin (Dilantin)
  • levetiracetam (Keppra)
  • theophylline (Theolair)

At-risk populations for deficiency:

  • patients with impaired renal function, autoimmune disorders such as rheumatoid arthritis (RA), or AUD (Johnson, 2020b; NIH, 2022n)

Biotin (vitamin B7) is a water-soluble vitamin that promotes nervous system functioning and helps the body metabolize fats, carbohydrates, and protein.

Biotin deficiency may present with/lead to:

  • thinning hair, scaly, red rash around body openings (eyes, nose, mouth, perineum), conjunctivitis, ketolactic acidosis, aciduria, seizures, skin infection, brittle nails, depression, lethargy, hallucinations, paresthesia of the extremities, hypotonia and developmental delays in infants, rash, and unusual distribution of facial fat

Medication interactions include:

  • carbamazepine (Tegretol)
  • primidone (Mysoline)
  • phenytoin (Dilantin)
  • phenobarbital (Luminal)
  • also interacts with laboratory tests for thyroid function

At-risk populations for deficiency:

  • individuals with biotinidase deficiency (rare autosomal recessive disorder) or AUD
  • pregnant or breastfeeding individuals (NIH, 2022a)

Folate (vitamin B9) is a water-soluble vitamin needed to produce mature red blood cells, synthesize DNA, promote tissue growth and cell function, and develop the fetal nervous system.

Folate deficiency may present with/lead to:

  • megaloblastic anemia (weakness, fatigue, difficulty concentrating, irritability, headaches, heart palpitations, shortness of breath), soreness of and shallow ulcerations on the tongue and oral mucosa, skin/hair/nail changes, GI symptoms, elevated serum homocysteine
  • pregnant individuals with folate deficiency are at risk of having infants with low birth weight, neural tube defects (NTD), preterm delivery, or fetal growth restriction
  • folate deficiency may play a role in autism spectrum disorder, cancer, CVD, stroke, dementia/Alzheimer’s disease, depression, and congenital heart defects

Medication interactions include:

  • methotrexate (Trexall)
  • phenytoin (Dilantin)
  • carbamazepine (Tegretol)
  • valproic acid (Depakene)
  • sulfasalazine (Azulfidine)

At-risk populations for deficiency:

  • patients with AUD, a malabsorptive disorder, or methylenetetrahydrofolate reductase (MTHFR) polymorphism
  • women of childbearing age
  • pregnant individuals (Johnson, 2020b; NIH, 2022f)

Cyanocobalamin (cobalamin, vitamin B12) is a water-soluble vitamin involved in red blood cell production, brain health, and DNA synthesis; cyanocobalamin is the synthetic form of vitamin B12 most frequently used in supplements.

B12 deficiency may present with/lead to:

  • megaloblastic anemia, fatigue, weakness, constipation, loss of appetite, weight loss, paresthesia, difficulty with balance, depression, confusion, dementia, poor memory, and soreness of tongue or mouth
  • infant symptoms include failure to thrive, movement disorders, developmental delays, or megaloblastic anemia

Medication interactions include:

  • chloramphenicol (Chloromycetin)
  • omeprazole (Prilosec)
  • lansoprazole (Prevacid)
  • cimetidine (Tagamet)
  • famotidine (Pepcid)
  • ranitidine (Zantac)
  • metformin (Glucophage)

At-risk populations for deficiency:

  • older adults
  • individuals with pernicious anemia or GI disorders
  • patients with a history of bariatric surgery
  • vegetarians
  • pregnant and lactating individuals and their infants (Johnson, 2020b; NIH, 2022o)

Vitamin C is a water-soluble antioxidant that helps strengthen the immune system and protect cells from destruction or damage linked to many diseases; it also promotes collagen and amino acid formation and wound healing.

Vitamin C deficiency may present with/lead to:

  • fatigue, malaise, inflammation of the gums, petechiae, ecchymosis (bruising), purpura (purple-colored spots on the skin), arthralgia, poor wound healing, hyperkeratosis (thickening of the outermost layer of the skin), corkscrew hairs, depression, swollen and bleeding gums, loose teeth, and iron deficiency anemia

Medication/treatment interactions include:

  • chemotherapeutic agents such as cyclophosphamide (Cytoxan), chlorambucil (Leukeran), carmustine (BiCNU), busulfan (Busulfex), thiotepa (Tepadina), and doxorubicin (Adriamycin)
  • radiation
  • 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) such as simvastatin (Zocor)

At-risk groups for vitamin C deficiency include:

  • smokers and passive smokers (second-hand smoke)
  • infants fed evaporated or boiled milk
  • individuals with limited access to a variety of foods
  • patients with any type of malabsorption disease, such as bariatric surgery patients
  • patients with end-stage renal disease (ESRD) on hemodialysis or cancer (Johnson, 2020b; NIH, 2021f)

Vitamin D is a fat-soluble vitamin that regulates the absorption of calcium and phosphorus, facilitates normal immune system function, and reduces the risk of autoimmune disease.

Vitamin D deficiency may present with/lead to:

  • osteomalacia (weakened bones), rickets, hypercalcemia, anorexia, renal failure, or metastatic calcifications
  • increases the risk of colon cancer, heart disease, and multiple sclerosis (MS)

Medication interactions include:

  • glucocorticoids such as prednisone (Deltasone)
  • orlistat (Alli)
  • cholestyramine (Questran)
  • phenobarbital (Luminol) and phenytoin (Dilantin) increase the metabolism of vitamin D and reduce calcium absorption

At-risk groups for vitamin D deficiency include:

  • breastfed infants
  • older adults
  • those with limited sun exposure
  • dark-skinned people
  • those with fat malabsorption (IBD, cystic fibrosis, celiac disease, or liver disease), obesity, or a history of bariatric surgery (Johnson, 2020b; NIH, 2022p)

Vitamin E is a fat-soluble antioxidant that protects cells from damage.

Vitamin E deficiency may present with/lead to:

  • peripheral neuropathy, ataxia, skeletal myopathy, retinopathy, impaired immune response, heart disease, or cognitive decline
  • increases the risk of colon, bladder, or breast cancer
  • increases the risk of age-related macular degeneration (AMD) or cataracts

Medication interactions include:

  • anticoagulants such as warfarin (Coumadin)
  • cholesterol-lowering drugs such as simvastatin (Zocor)
  • niacin (Niaspan)

At-risk groups for vitamin E deficiency include:

  • premature babies below 1500 grams
  • those with a fat malabsorption disorder (IBD, cystic fibrosis, celiac disease, or liver disease), obesity, or a history of bariatric surgery (Johnson, 2020b; NIH, 2021g)

Vitamin K is a fat-soluble vitamin that helps form prothrombin and other coagulation factors, facilitates bone metabolism, and regulates blood calcium levels.

Vitamin K deficiency may present with/lead to:

  • bleeding or hemorrhage and reduced bone mineralization (osteoporosis)

Medication interactions include:

  • warfarin (Coumadin)
  • cefoperazone (Cefobid)
  • bile acid sequestrants such as cholestyramine (Questran) and colestipol (Colestid)
  • orlistat (Alli)

At-risk groups for vitamin K deficiency include:

  • newborns not supplemented with vitamin K at birth
  • those with fat malabsorption (IBD, cystic fibrosis, celiac disease, or liver disease), obesity, or a history of bariatric surgery (Johnson, 2020b; NIH, 2021h)


Table 3

Recommended Daily Allowances of Vitamins 


Males aged 18+

Females aged 18+



Vitamin A 

900 mcg RAE

700 mcg RAE

770 mcg RAE

1300 mcg RAE

Thiamine (B1)

1.2 mg

1.1 mg

1.4 mg

1.4 mg

Riboflavin (B2)

1.3 mg

1.1 mg

1.4 mg

1.6 mg

Niacin (B3)

16 mg

14 mg

18 mg

17 mg

Pantothenic Acid (B5)

5 mg

5 mg

6 mg

7 mg

Pyridoxine (B6) - AI

1.3 mg

1.3 mg

1.9 mg

2.0 mg

Biotin (B7) - AI

30 mcg

30 mcg

30 mcg

35 mcg

Folate (B9)

400 mcg DFE

400 mcg DFE

600 mcg DFE

500 mcg DFE

Cyanocobalamin (B12)

2.4 mcg

2.4 mcg

2.6 mcg

2.8 mcg

Vitamin C

90 mg

75 mg

85 mg

120 mg

Vitamin D 

600 IU

Age > 71 800 IU

600 IU

Age > 71 800 IU

600 IU

600 IU

Vitamin E

15 mg

15 mg

15 mg

19 mg

Vitamin K

120 mcg

90 mcg

90 mcg

90 mcg

(Johnson, 2022b; NIH, 2021c, 2022; USDA, 2020)



Complete nutrition is dependent on both vitamins and minerals. The body uses minerals to maintain the functionality of the bones, muscles, brain, and heart. Minerals are also necessary for making hormones and enzymes. There are two types of minerals: macrominerals and trace minerals. Macrominerals are needed in larger quantities and include calcium, potassium, sodium, phosphorus, magnesium, chloride, and sulfur. Trace minerals, including iron, copper, iodine, manganese, zinc, fluoride, cobalt, and selenium, are only required in small amounts. Generally, minerals are obtained through dietary intake, but a mineral supplement may be recommended for those who lack a varied diet. Individuals with certain health conditions, such as chronic kidney disease, must limit their intake of certain minerals, such as potassium, due to adverse effects from decreased elimination (Johnson, 2020a). See Table 4 for minerals and their implications and Table 5 for their RDAs.


Table 4


Dietary Supplement and Potential Benefits

Nursing Implications/Alerts

Calcium supplementation decreases the risk of rickets, osteoporosis, and dental problems and may reduce the risk of preeclampsia.

Hypercalcemia can cause:

  • renal insufficiency, vascular and soft tissue calcification, hypercalciuria, and kidney stones

Hypocalcemia can cause:

  • neuromuscular irritability, perioral numbness, paresthesia, and muscle spasms

Calcium supplements may interact with the following:

  • bisphosphonates such as etidronate (Didronel)
  • fluoroquinolone antibiotics such as ciprofloxacin (Cipro)
  • tetracycline (Tetracon)
  • levothyroxine (Synthroid)
  • phenytoin (Dilantin)
  • tiludronate disodium (Skelid)
  • thiazide-type diuretics such as hydrochlorothiazide (Microzide)
  • aluminum and magnesium-containing antacids increase urinary calcium excretion, and mineral oil or stimulant laxatives decrease calcium absorption
  • extended use of glucocorticoids such as prednisone (Deltasone) causes calcium depletion and leads to osteoporosis

At-risk groups for calcium deficiency include:

  • postmenopausal women
  • individuals that do not consume dairy products (Johnson, 2020a; NIH, 2022b)

Chromium aids digestion, slows calcium loss to avoid osteoporosis, and promotes glucose tolerance; bodybuilders use chromium to aid in burning fat and building muscle.

Currently, there is no evidence that increased or decreased intake of dietary chromium leads to adverse effects

The following medications may cause a decrease in the absorption of chromium:

  • prednisone (Deltasone)
  • H2 blockers such as cimetidine (Tagamet) or famotidine (Pepcid)
  • proton-pump inhibitors such as omeprazole (Prilosec) or pantoprazole (Protonix)

Increased effects of chromium may be experienced if taken with:

  • atenolol (Tenormin)
  • propranolol (Inderal)
  • insulin
  • niacin
  • NSAIDs such as ketorolac (Toradol), ibuprofen (Motrin, Advil), or aspirin (Ecotrin; Johnson, 2020a; NIH, 2022c)

Copper promotes brain development, immune system function, iron metabolism, and energy production and may prevent CVD and Alzheimer’s.

Copper deficiency is associated with the following:

  • anemia, hypopigmentation, hypercholesterolemia, osteoporosis and other bone defects, connective tissue disorders, ataxia, an increased risk of infection, and abnormal lipid metabolism

At-risk groups for copper deficiency include:

  • patients with celiac disease or Menkes syndrome (a rare, X-linked, recessive disorder)
  • individuals taking high doses of zinc (zinc interferes with copper absorption)

Copper toxicity is associated with the following:

  • nausea, vomiting, diarrhea, abdominal pain, liver disease

At-risk groups for copper toxicity include:

  • individuals with copper-containing pipes (allows copper to leak into the water supply)
  • patients with Wilson's disease, an autosomal recessive disease that affects copper clearance and requires copper chelation therapy to remove copper (Johnson, 2020a; NIH, 2022d)

Fluoride inhibits or reverses the activation or progression of tooth decay and promotes bone formation.

At-risk groups for fluoride deficiency include those without fluoridated water (e.g., well water)

Fluoride deficiency can result in weak bones (i.e., osteoporosis) and teeth (i.e., dental caries)

Excess fluoride can cause:

  • nausea, vomiting, abdominal pain, and diarrhea
  • white lines or brown streaks on the teeth if it occurs in infancy or childhood before tooth eruption
    • parents should avoid fluoride supplements or fluoride toothpaste before 2 years of age and avoid fluoride mouth rinses in children under 6 (Johnson, 2020a; NIH, 2022e)

Iodine is essential in thyroxine (T4) and triiodothyronine (T3) production and fetal development.


Iodine deficiency may cause:

  • thyroid cancer, goiter, fibrocystic breast disease, congenital hypothyroidism, or impaired fetal growth and brain development (the leading cause of preventable intellectual disability)

At-risk groups for iodine deficiency include:

  • individuals that do not use iodized salt or live in an area with iodine-deficient soil, pregnant women, vegans

Excess iodine can cause:

  • thyroiditis, papillary thyroid cancer, goiter, and acute iodine poisoning (burning of the mouth, throat, and stomach)

Iodine dietary supplements may interact with the following:

  • methimazole (Tapazole)
  • angiotensin-converting enzyme (ACE) inhibitors such as benazepril (Lotensin) or lisinopril (Prinivil)
  • potassium-sparing diuretics such as spironolactone (Aldactone; Johnson, 2020a; NIH, 2022g)

Iron is an essential component of hemoglobin and myoglobin and supports muscle metabolism, healthy connective tissue, and hormone synthesis.

Iron deficiency may cause:

  • anemia, pica, and glossitis

Groups at risk for iron deficiency include:

  • women (pregnant and those with heavy menstrual cycles)
  • infants and young children
  • frequent blood donors
  • patients with cancer, IBS, heart or renal failure, or a history of bariatric surgery

Iron toxicity may cause:

  • cirrhosis, diabetes mellitus, or skin discoloration

Iron supplements may interact with the following:

  • levodopa (Sinemet)
  • levothyroxine (Synthroid); take iron dietary supplements at least 4 hours before or after
  • PPIs such as omeprazole (Prilosec) reduce iron absorption (Johnson, 2020a; NIH, 2022h)

Magnesium is responsible for energy production and other biochemical reactions, such as the calcium/potassium transport across cell membranes vital to nerve impulse conduction, normal heart rhythm, and muscle contractions.

Signs of hypomagnesemia are rare but include the following:

  • nausea, vomiting, fatigue, anorexia, arrhythmias, muscle cramps, and seizures

At-risk groups for hypomagnesemia include:

  • patients with malabsorption disorders such as IBD, celiac disease, AUD, a history of bariatric surgery, type 2 diabetes
  • older adults

Signs of hypermagnesemia include:

  • diarrhea, nausea, abdominal cramps, hypotension, facial flushing, and urinary retention

Magnesium supplements interact with:

  • bisphosphonates such as alendronate (Fosamax)
  • tetracyclines
  • loop diuretics
  • PPIs such as esomeprazole (Nexium; NIH, 2022i)

Manganese is a cofactor for several enzymes: it is involved in amino acid, cholesterol, glucose, and carbohydrate metabolism, bone formation, reproduction, blood clotting, and homeostasis in relation to vitamin K, as well as the immune response.

Manganese deficiency is rare but may cause:

  • bone demineralization and poor growth in children, rashes, hair depigmentation, decreased serum cholesterol, and increased alkaline phosphatase activity in men or increased premenstrual pain, altered mood, or osteoporosis in women

Symptoms of manganese toxicity include:

  • central nervous system depression, tremor, tinnitus, hearing loss, muscles spasms, mania, depression, headaches, irritability, or reduced hand-eye coordination

At-risk groups for manganese toxicity include:

  • individuals with iron deficiency due to increased manganese absorption or chronic liver disease due to impaired elimination
  • individuals who work in welding and mining due to the inhalation of manganese dust (NIH, 2021a)

Molybdenum is required for the function of the enzymes sulfite oxidase, xanthine dehydrogenase, aldehyde oxidase, and mitochondrial amidoxime-reducing component (mARC), which metabolize drugs and toxins.

Molybdenum deficiency:

  • has only been reported in individuals with the rare genetic metabolic disorder, molybdenum cofactor deficiency, which prevents biosynthesis and impairs the function of enzymes that metabolize sulfite
  • causes seizures and encephalopathy resulting in neurological damage and death within days after birth (Johnson, 2020a; NIH, 2021ab)

Nickel may help to prevent osteoporosis (due to its influence on intracellular calcium content) and anemia.

Nickel deficiency can cause:

  • decreased sperm production, osteoporosis, increased lipids, hypoglycemia, and anemia

Nickel toxicity is unlikely as a result of oral intake

Allergies to nickel have been reported and can be exacerbated by oral intake (Nielsen, 2021)

Phosphorus is an essential mineral and a component of bones, teeth, genetic material (i.e., DNA and RNA), the cell membrane structure, and adenosine triphosphate (ATP, the body’s essential energy source).

Hypophosphatemia is extremely rare, but the effects can include:

  • anorexia, anemia, muscle weakness, ataxia, and confusion

Groups at risk of deficiency include:

  • preterm newborns and individuals with genetic phosphate regulation disorders or severe malnutrition

Phosphorus interacts with several medications, and some medications can alter phosphate levels, including:

  • antacids that contain aluminum hydroxide (i.e., Maalox HRF, Rulox) bind phosphates in the intestines and can lead to hypophosphatemia
  • antacids containing calcium carbonate (i.e., Rolaids, Tums, and Maalox) decrease the intestinal absorption of dietary phosphorus
  • enema preparations (i.e., Fleet) may contain sodium phosphate, which can increase serum phosphorus levels (NIH, 2021d)

Potassium maintains intracellular and extracellular fluid volume, including plasma volume; sodium and potassium have a strong relationship; most potassium is found intracellularly and is required for proper muscle contraction, nerve transmission, and kidney function.

The FDA mandates that any supplement containing more than 99 mg of potassium must carry a warning label regarding small-bowel lesions, which can lead to obstruction, bleeding, or perforation.

Hypokalemia can cause:

  • hypertension, urinary calcium excretion, bone turnover, and increased risk of kidney stones and cardiac arrhythmias

Causes of hypokalemia include:

  • diuretic use, which can lead to severe hypokalemia (serum potassium level under 3.6 mmol/L), laxative abuse, heavy sweating, or dialysis

Hyperkalemia can cause:

  • weakness, paralysis, heart palpitations, and life-threatening arrhythmias

Medications that can affect potassium levels include:

  • ACE inhibitors (i.e., benazepril [Lotensin]), angiotensin receptor blockers (ARBs, i.e., losartan [Cozaar]), and potassium-sparing diuretics including amiloride (Midamor) and spironolactone (Aldactone) increase the risk of hyperkalemia
  • loop diuretics such as furosemide (Lasix) and thiazide diuretics such as chlorothiazide (Diuril) can cause hypokalemia (NIH, 2022k)

Selenium is nutritionally essential and is critical in reproduction, DNA synthesis, thyroid hormone metabolism, and immune function.

Selenium deficiency is associated with colorectal, lung, skin, esophageal, prostate, bladder, and gastric cancers

Individuals at risk for selenium deficiency include:

  • those with HIV or ESRD undergoing hemodialysis
  • those living in selenium-deficient regions

Selenium supplementation may be considered for diseases where sufficient levels affect the disease process, such as cancer, cognitive decline, thyroid disease, and CVD.

Excessive selenium intake can result in the following:

  • a garlic odor to the breath and a metallic taste in the mouth, hair loss, brittle nails, skin lesions, nausea, diarrhea, mottled teeth, fatigue, and irritability

Medications that interact with selenium include:

  • cisplatin (Platinol)
  • anticoagulants (i.e., clopidogrel [Plavix], enoxaparin [Lovenox], warfarin [Coumadin])
  • cholesterol-lowering medications (i.e., lovastatin [Mevacor], pravastatin [Pravachol])
  • barbiturates
  • oral contraceptives (i.e., ethinyl estradiol/levonorgestrel [Triphasil], ethinyl estradiol/norethindrone [Ortho-Novum]; Johnson, 2020a; NIH, 2021e)

Sodium is required for nerve and muscle function and proper fluid balance.

Groups sensitive to hypernatremia include African Americans, adults over 50, and those with diabetes or kidney disease.

Hypernatremia can lead to hypertension and other cardiovascular effects.

Drugs that interact with sodium chloride include lithium (Eskalith, Lithobid) and tolvaptan (Jynarque)

Hyponatremia can be caused by:

  • excess exercise, vomiting, diuretic use, burns affecting large portions of the body, heart failure, or diarrhea (Centers for Disease Control and Prevention, 2021)

Zinc is involved in cellular metabolism, immune function, wound healing, protein synthesis, DNA synthesis, and cell division; it is vital for growth and development during pregnancy, childhood, and adolescence and a functioning sense of taste and smell.

Zinc deficiency is characterized by the following:

  • anorexia, growth retardation, and impaired immunity
  • hair loss, impotence, delayed sexual maturation, hypogonadism (in males), eye and skin lesions, weight loss, mental lethargy, or taste abnormalities (if severe)

Zinc deficiency is uncommon in the US, but at-risk groups include:

  • those with inadequate intake, such as vegetarians, pregnant or lactating women, exclusively breastfed older infants, or patients with AUD
  • patients with malabsorption related to GI disorders or previous bariatric surgery

Excessive zinc intake can cause:

  • nausea, vomiting, dizziness, loss of appetite, and neutropenia

Large amounts of supplemental iron can reduce zinc absorption, and high zinc intake can inhibit copper absorption; thus, most dietary supplements with high levels of zinc may also contain copper

Zinc supplements can interact with medications such as:

  • antibiotics, including quinolones (ciprofloxacin [Cipro]) and tetracycline (Sumycin); antibiotics should be taken 2 hours prior or 4-6 hours after zinc consumption
  • penicillamine (Cuprimine, Depen); should be separated by at least 2 hours
  • thiazide diuretics such as hydrochlorothiazide (HCTZ) or chlorthalidone (Hygroton) increase urinary zinc excretion by up to 60%, and the prolonged use of these diuretics can deplete zinc levels (Johnson, 2020a; NIH, 2022q)


Table 5

Recommended Daily Allowances of Minerals


Males aged 18+

Females aged 18+




1,000 mg

1,000 mg

1,000 mg

1,000 mg







35 mcg

25 mcg

30 mcg

45 mcg


900 mcg

900 mcg

1000 mcg

1300 mcg


4 mg

3 mg

3 mg

3 mg


150 mcg

150 mcg

220 mcg

290 mcg


8 mg

18 mg

27 mg

9 mg


400-420 mg

310-320 mg

350 mg

310 mg


2.3 mg

1.8 mg

2.0 mg

2.6 mg


45 mcg

45 mcg

50 mcg

50 mcg







700 mg

700 mg

700-1250 mg

700 mg


3,400 mg

2,600 mg

2,900 mg

2,800 mg


55 mcg

55 mcg

60 mcg

70 mcg


2,300 mg

2,300 mg

2,300 mg

2,300 mg


11 mg

8 mg

11 mg

12 mg

(Johnson, 2022a; USDA, 2020)


A botanical is a plant or plant portion used for its therapeutic or medicinal properties, flavors, or scents. Herbs are a type of botanical. Products made from botanicals to maintain or improve health are called botanical products, herbal products, or phytomedicines. Botanicals may be sold as fresh or dried products, liquid or solid extracts, tablets, capsules, powders, or teas. Typically, dietary supplements are in tablet or capsule forms. Botanicals may have specific chemicals known as markers used to manufacture a consistent or standardized product; this should be the portion of the botanical that provides the therapeutic effect. It is difficult to determine the quality of a botanical dietary supplement from its label as the quality is related to the manufacturer, supplier, and production process. Many people take botanicals and herbs for various conditions because they are natural substances, but the validity of their usefulness is primarily unsubstantiated by research. Many of these dietary supplements can be harmful, causing severe adverse effects. Pregnant individuals and those who take anticoagulation therapy or have bleeding disorders are at the highest risk of experiencing adverse effects (NIH, 2020b). See Table 6 for common botanicals and herbs.


Table 6


Dietary Supplement and Dosing Information

Potential Indications

Nursing Implications/Alerts

Black cohosh

  • doses range from 6.5 to 160 mg/d
  • median dose of 40 mg/d

Promoted for menopausal symptoms, sleep disturbances, irritability, or heart palpitations

  • limit use to 6 months or less due to the risk of liver damage with long-term use or high doses
  • instruct patients to report abdominal pain, dark urine, or jaundice
  • not advised for patients with estrogen-receptor-positive cancers (i.e., breast; NIH, 2020a)


  • dosing ranges from 2400-4000 mg/d

May prevent or treat infections such as the common cold by boosting the human immune system or topically for skin wounds or conditions

  • short-term use is considered safe, but long-term safety is not proven
  • common adverse effects include nausea, stomach pain, or allergic reaction
  • no significant drug interactions (National Center for Complementary and Integrative Health [NCCIH], 2020a)


  • 1000-7200 mg/d for hyperlipidemia

300-1500 mg/d for hypertension

1 mg/kg/d for cancer prevention

May prevent the common cold and colon or stomach cancer; it may treat hypertension or hyperlipidemia

  • may interact with blood thinners such as warfarin (Coumadin) and antiviral drugs such as saquinavir (Invirase) and ritonavir (Norvir; NCCIH, 2020b)

Ginkgo biloba

  • dosing ranges from 120-240 mg/d

Promoted for dementia, intermittent claudication, glaucoma, vertigo, or tinnitus

  • adverse effects include constipation, headaches, dizziness, and palpitations
  • increased risk of bleeding with concurrent use of warfarin (Coumadin) and during pregnancy
  • increased risk of liver and thyroid cancer
  • avoid consumption of raw or roasted seeds of the plant due to toxicity (NCCIH, 2020c)

Saw palmetto

  • doses range from 160-230 mg/d

Promoted for treatment of urinary symptoms associated with benign prostatic hyperplasia, chronic pelvic pain, migraines, hair loss, or decreased sex drive

  • use with caution during pregnancy and while breastfeeding
  • no significant drug interactions
  • may cause digestive symptoms or headaches (NCCIH, 2020d)

St. John’s wort

  • dosing ranges from 750-900 mg/d

Promoted for depression, menopausal symptoms, attention-deficit hyperactivity disorder (ADHD), and obsessive-compulsive disorder (OCD)

  • interacts with numerous medications, including antiretroviral drugs, chemotherapeutics such as irinotecan HCL (Camptosar), antidepressants, cyclosporine (Neoral), digoxin (Lanoxin), oral contraceptives, and warfarin (Coumadin)
  • monitor for suicidal ideations in patients taking St. John's wort for depression (NCCIH, 2020e)


Amino Acids

Amino acids are the building blocks of proteins. They naturally occur in foods but can also be taken as dietary supplements. Amino acids are categorized as either essential (or indispensable), nonessential, or conditionally essential. Although many amino acids are present in nature, only twenty specific amino acids are needed to produce all the proteins in the human body. Nine are essential (histidine, leucine, methionine, threonine, valine, L-tryptophan, isoleucine, lysine, and phenylalanine) because the body cannot produce them endogenously. Optimal sources for amino acids are animal proteins, including meat, eggs, and poultry. Proteins are broken down into amino acids for use by the body. Six remaining amino acids are considered conditionally essential (arginine, cysteine, proline, tyrosine, glutamine, and glycine). Conditionally essential amino acids become essential under particular circumstances such as stress or illness (i.e., cancer, wound healing, liver disease, premature infants). Nonessential amino acids include those produced endogenously by the body (alanine, asparagine, aspartic acid, glutamic acid, and serine; Blachier et al., 2021; Lopez & Mohiuddin, 2023). See Table 7 for a listing of amino acids and their nursing implications. A complete listing can be found in the US National Library of Medicine-Herbs and Supplements for further information on various amino acids in dietary supplements.

Table 7

Amino Acids

Essential Amino Acids

Physiologic Role

Typical Dosing

Nursing Implications/Alerts

Phenylalanine is required for the function of proteins and enzymes and is a precursor for neurotransmitters.

33 mg/kg/d

  • phenylalanine can act as a neurotoxin at high levels
  • the genetic disorder phenylketonuria (PKU) impairs phenylalanine function

Valine stimulates muscle growth and regeneration and is involved in energy production.

24 mg/kg/d

  • may decrease the absorption of levodopa (Sinemet)
  • may cause hypoglycemia if used with antidiabetic medications

Threonine is needed for protein, glycine, and acetyl-CoA synthesis.

20 mg/kg/d

  • used in disorders marked by muscle tightness and involuntary movements, such as MS or amyotrophic lateral sclerosis (ALS)

L-tryptophan is required for serotonin production, which regulates mood, behavior, and sleep.

5 mg/kg/d

  • may be effective with smoking cessation, teeth grinding, and myofascial pain syndrome
  • associated with drowsiness

Methionine is involved in producing cysteine to build proteins and is required to synthesize biologically active sulfur.

19 mg/kg/d

  • can be used to treat patients with liver disease, viral infection, AUD, pancreatitis, depression, allergies, asthma, radiation side effects, schizophrenia, drug withdrawal, or symptoms of a urinary tract infection (UTI)
  • can prevent liver damage when taken after an acetaminophen (Tylenol) overdose
  • may reduce the risk of breast and colon cancer, neural tube defects, and hot flashes

Leucine is crucial for muscle repair and protein synthesis.

42 mg/kg/d

  • helps regulate blood glucose levels
  • produces growth hormones
  • stimulates wound healing

Isoleucine induces muscle protein synthesis.

19 mg/kg/d

  • increases glucose uptake during exercise
  • used as a performance enhancer by athletes
  • essential for immune function, energy regulation, and hemoglobin production

Lysine is involved in protein synthesis, hormone and enzyme production, collagen and elastin production, and calcium absorption.

38 mg/kg/d

  • enhances energy production and immune function

Histidine is a precursor for several hormones and critical metabolites affecting renal function, neurotransmission, gastric secretion, and immune function.

14 mg/kg/d

  • used for metabolic syndrome, diarrhea related to cholera infection, RA, gastric ulcers, anemia associated with renal failure, and allergic conditions

Nonessential and Conditionally Essential Amino Acids

Glutamine plays a critical role in the immune system and GI health.

35-50 mg/kg/d

  • can decrease the risk of infection, improve overall health, and shorten hospital stays in comparison to placebos
  • used with burn patients and severe infections for improved outcomes
  • bodybuilders use it to decrease fatigue and muscle soreness after exercise

Aspartate increases the absorption of minerals and may improve athletic performance.

No recommended dietary intakes listed

  • may be used with liver failure to slow brain damage
  • often combined with minerals to enhance absorption, such as copper aspartate

L-arginine is involved in wound healing, maintaining immune and hormone function, and vasodilation.

2000-3000 mg/d

  • used in the treatment of hypertension, angina, peripheral artery disease, and erectile dysfunction
  • may interact with medications such as captopril (Capoten), enalapril (Vasotec), diltiazem (Cardizem), nitroglycerin (Nitro-Bid, Nitro-Dur, (Nitrostat), isosorbide (Imdur, Isordil), or sildenafil (Viagra)

Ornithine is thought to increase arginine levels and may also elevate hormone levels associated with increasing muscle size.

2000 mg/d for 7 days, then 3000 mg before exercise; 1000 mg/d may be taken in combination with arginine routinely

  • primarily used for performance enhancement in athletes
  • may be used for weight loss, improved sleep quality, or wound healing

Tyrosine is involved in protein production and is a precursor for adrenaline, noradrenaline, and dopamine.

500-2000 mg/d in most adults;

up to 7600 mg/d to treat PKU

  • used to treat PKU since these individuals cannot consume foods high in phenylalanine, resulting in a tyrosine deficiency
  • interacts with monoamine oxidase inhibitors (MAOIs), thyroid hormones, and levodopa (Sinemet)

Taurine is involved in brain and nerve growth and appears to calm the sympathetic nervous system.

1500-6000 mg/d

  • may interact with lithium (Lithobid), causing toxic levels
  • used in patients with hepatitis, cystic fibrosis, diabetes, or chemotherapy-related nausea and vomiting
  • may improve memory or cognitive functioning, athletic performance, and energy levels

(Blachier et al., 2021; Institute of Medicine [IOM], 2005; Kubala, 2023)

Branched-Chain Amino Acids (BCAAs)

Three essential amino acids, leucine, isoleucine, and valine, belong to the particular class of amino acids known as BCAAs. BCAAs are primarily found in eggs, meat, and dairy products. BCAAs provide five benefits: increased muscle growth, decreased muscle soreness, reduced exercise fatigue, prevention of muscle wasting, and improved liver diseases such as cirrhosis. BCAA supplementation of 200-240 mg/kg/day has also been shown to reduce blood glucose levels. However, BCCAs should be avoided during pregnancy and breastfeeding as insufficient information supports the use or implications. BCAAs are also contraindicated in patients with ALS due to an increased risk of respiratory failure and should not be used with branched-chain ketoaciduria, as seizures can result (Mann et al., 2021).



Probiotics are living microorganisms that have health benefits when consumed or applied to the human body. Sources include yogurt, dietary supplements, and beauty products. Most people consider bacteria or microorganisms potentially harmful, yet many bacteria benefit digestion, produce vitamins, or destroy disease-causing cells. The microorganisms in probiotic dietary supplements are like the microorganisms found in humans naturally. Probiotic supplements contain several microorganisms, but the most commonly used belong to Lactobacillus or Bifidobacterium groups. The yeast used as a probiotic is Saccharomyces boulardi (NCCIH, 2019).

Probiotics are the third most commonly used dietary supplement behind vitamins and minerals. Probiotics work by helping the body maintain a healthy community of cooperative microorganisms or return to a healthy condition after an illness or the use of certain medications such as antibiotics. They influence the body's immune response and support optimal GI health. While many studies related to probiotics are inconclusive, some areas of study have shown promise. Research has favored using probiotics to prevent antibiotic-associated diarrhea, necrotizing enterocolitis, sepsis in infants, and treating infant colic or periodontal disease. Other claims by manufacturers of probiotics are related to decreasing or preventing allergies, skin conditions such as acne, dental caries, UTIs, and upper respiratory infections. Probiotics appear to be safe, with few, if any, adverse effects in healthy individuals. The risk of side effects increases with immunocompromised patients or those with severe illnesses. Some probiotic supplements may contain additional microorganisms other than the ones listed on the label, and those contaminants could pose health risks (International Scientific Association for Probiotics and Prebiotics [ISAPP]; 2022; NCCIH, 2019). See Table 8 for information about probiotics.


Table 8


Dietary Supplement



Nursing Implications/Alerts

Lactobacillus acidophilus

A bacterium found in the human intestines and an ingredient found in fermented foods such as yogurt, sauerkraut, miso, tempeh, or dietary supplements; it aids in digestion and produces lactic acid by breaking down lactose.

1-2 capsules per day; or 1-10 billion colony forming units (CFU) in 3-4 divided doses

Common side effects include bloating and flatulence (gas).

Lactobacillus acidophilus is associated with reduced cholesterol and weight loss, decreased diarrhea among hospitalized children, improved IBS symptoms, and treatment or prevention of vaginal infections, particularly after antibiotic use.

(ISAPP, 2022; NCCIH, 2019)

Fish Oil

Fish oil is a dietary source of omega-3 fatty acids, which are polyunsaturated fatty acids needed for numerous body functions ranging from muscle activity to cellular growth. Specific functions include blood clotting, cell division and growth, and fertility. Fish oil supplements typically contain two omega-3 fatty acids: docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). DHA is needed for brain development and function. Omega-3 fatty acids are found in many foods. The primary dietary sources for DHA and EPA are cold-water fatty fish such as salmon, mackerel, trout, mussels, oysters, shellfish, and crabs. Other foods such as eggs, yogurt, infant formula, and milk may be fortified with DHA and other omega-3s. Nuts, seeds, and vegetable oils (including flaxseed, soybean, and canola) also contain a third omega-3 fatty acid, alpha-linolenic acid (ALA). ALA must be obtained from food sources since the body cannot make it. Similarly, EPA and DHA are mainly obtained from food sources as the body can only convert ALA into EPA and then DHA in minimal amounts (roughly 15%). In addition to dietary consumption, EPA and DHA can be supplemented via fish oil. Research supports using fish oil supplements to reduce the risk of CVD, hypertension, elevated triglycerides or cholesterol, preterm delivery, and RA (NIH, 2023b; Shane-McWhorter, 2023). See Table 9 for more information regarding fish oils.


Table 9

Fish Oil


Typical Dosing

Nursing Implications/Alerts

Omega-3 fatty acids are needed for numerous body functions ranging from muscle activity to cellular growth, such as clotting of blood, cell division and growth, and fertility.

  • uses include the prevention or treatment of CVD, RA, macular degeneration, depression, and cyclosporine nephrotoxicity


The AI of ALA is 0.5-1.2 g in infants/children and 1.1-1.6 in adolescents/adults.

A 1 g fish oil supplement typically provides approximately 300 mg of combined EPA and DHA.

Side effects include fishy eructation, nausea or indigestion, loose stools, or rash

Use with caution in those with allergies to shellfish

Interacts with the following medications:

  • anticoagulants such as warfarin (Coumadin)
  • antihypertensive medications: results in severe hypotension
  • contraceptive drugs: make the fish oil less effective in triglyceride reduction
  • orlistat (Alli): may cause a decreased absorption of fatty acids; should be taken 2 hours apart
  • may reduce vitamin E levels

(NIH, 2023b; Shane-McWhorter, 2023)



The NCCIH states that dietary supplements have many ingredients which may not appear on their labels. While there have been many studies on dietary supplements with evidence of value, many do not have solid clinical research that confirms their efficacy in treating or preventing various conditions. Safe use of supplements requires that the user read the label carefully and follow the directions for safe use. Also, the user should remember that natural sources do not always translate to safety, mainly where herbs or botanicals are concerned. Often unknown or multiple ingredients are in the products. There is always the possibility of food or drug interactions with dietary supplements, and some of the interactions pose a severe risk. While significant interactions have been shared in this module, other risks could exist. Most supplements are not approved for children or pregnant/breastfeeding women. Finally, while the FDA oversees dietary supplements, their regulation is much less rigorous or controlled than prescription or over-the-counter medications (NIH, 2023a).


Bhupathiraju, S. N., & Hu, F. (2023). Overview of nutrition. Merck Manual Professional Version. https://www.merckmanuals.com/professional/nutritional-disorders/nutrition-general-considerations/overview-of-nutrition

Blachier, F., Blais, A., Elango, R., Saito, K., Shimomura, Y., Kadowaki, M., & Matsumoto, H. (2021). Tolerable amounts of amino acids for human supplementation: Summary and lessons from published peer-reviewed studies. Amino Acids, 53, 1313-1328. https://doi.org/10.1007/s00726-021-03054-z

Centers for Disease Control and Prevention. (2021). Sodium. https://www.cdc.gov/heartdisease/sodium.htm

Dietary Guidelines Advisory Committee. (2020). Scientific report of the 2020 dietary guidelines advisory committee. US Department of Agriculture. https://health.gov/sites/default/files/2019-09/Scientific-Report-of-the-2015-Dietary-Guidelines-Advisory-Committee.pdf

Institute of Medicine. (2005). Dietary reference intakes for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein, and amino acids. The National Academies Press. https://doi.org/10.17226/10490

International Scientific Association for Probiotics and Prebiotics. (2022). The ISAPP quick guide to probiotics for health professionals: History, efficacy, and safety. https://isappscience.org/for-clinicians/resources/probiotics

Johnson, L. E. (2022a). Overview of minerals. Merck Manual Professional Version. https://www.merckmanuals.com/professional/nutritional-disorders/mineral-deficiency-and-toxicity/overview-of-minerals

Johnson, L. E. (2022b). Overview of vitamins. Merck Manual Professional Version. https://www.merckmanuals.com/professional/nutritional-disorders/vitamin-deficiency,-dependency,-and-toxicity/overview-of-vitamins

Kantor, E. D., Rehm, C. D., Du, M., White, E., & Givannucci, E. L. (2016). Trends in dietary supplement use among US adults from 1999-2012. JAMA, 316(14) 1464-1474. https://doi.org/ 10.1001/jama.2016.14403.

Kubala, J. (2023). Essential amino acids: Definition, benefits, and food sources. Healthline. https://www.healthline.com/nutrition/essential-amino-acids

Lopez, M. J., & Mohiuddin, S. S. (2023). Biochemistry, essential amino acids. StatPearls [Internet]. https://www.ncbi.nlm.nih.gov/books/NBK557845

Mann, G., Mora, S., Madu, G., & Adegoke, O. A. J. (2021). Branched-chain amino acids: Catabolism in skeletal muscle and implications for muscle and whole-body metabolism. Frontiers in Physiology, 12. https://doi.org/10.3389/fphys.2021.702826

McCance, K. L., & Huether, S. E. (2019). Pathophysiology: The biologic basis for disease in adults and children (8th ed.). Elsevier.

Mikulic, M. (2022). Dietary supplement usage in the US adults by age 2020. Statista. Scientific report of the 2015 dietary guidelines advisory committee. https://www.statista.com/statistics/307917/dietary-supplement-usage-us-adults-by-age-group

Mozaffarian, D., Rosenberg, I., & Uauy, R. (2018). History of modern nutrition science-implications for current research, dietary guidelines, and food policy. BMJ, 361, k2392. https://doi.org/10.1136/bmj.k2392.

National Academies of Sciences, Engineering, and Medicine. (n.d.). About the Food and Nutrition Board. Retrieved April 6, 2023, from https://www.nationalacademies.org/fnb/about

National Cancer Institute. (n.d.). NCI dictionary of cancer terms. Retrieved April 4, 2023, from https://www.cancer.gov/publications/dictionaries/cancer-terms/def/fat-soluble-vitamin

National Center for Complimentary and Integrative Health. (2019). Probiotics: What you need to know. https://www.nccih.nih.gov/health/probiotics-what-you-need-to-know

National Center for Complimentary and Integrative Health. (2020a). Echinacea. https://www.nccih.nih.gov/health/echinacea

National Center for Complimentary and Integrative Health. (2020b). Garlic. https://www.nccih.nih.gov/health/garlic

National Center for Complimentary and Integrative Health. (2020c). Ginkgo. https://www.nccih.nih.gov/health/ginkgo

National Center for Complimentary and Integrative Health. (2020d). Saw palmetto. https://www.nccih.nih.gov/health/saw-palmetto

National Center for Complimentary and Integrative Health. (2020e). St. John’s wort. https://www.nccih.nih.gov/health/st-johns-wort

National Institutes of Health. (n.d.-a). Dietary supplement fact sheets. Retrieved April 6, 2023, from https://ods.od.nih.gov/factsheets/list-all

National Institutes of Health. (n.d.-b). Nutrient recommendations and databases. Retrieved April 6, 2023, from https://ods.od.nih.gov/HealthInformation/nutrientrecommendations.aspx

National Institutes of Health. (n.d.-c). Promoting vitamin C. https://profiles.nlm.nih.gov/spotlight/mm/feature/medicine

National Institutes of Health. (2020a). Black cohosh. https://ods.od.nih.gov/factsheets/BlackCohosh-HealthProfessional

National Institutes of Health. (2020b). Botanical dietary supplements: Background information. https://ods.od.nih.gov/factsheets/BotanicalBackground-HealthProfessional

National Institutes of Health. (2021a). Manganese. https://ods.od.nih.gov/factsheets/Manganese-HealthProfessional

National Institutes of Health. (2021b). Molybdenum. https://ods.od.nih.gov/factsheets/Molybdenum-HealthProfessional

National Institutes of Health. (2021c). Pantothenic acid. https://ods.od.nih.gov/factsheets/PantothenicAcid-HealthProfessional

National Institutes of Health. (2021d). Phosphorus. https://ods.od.nih.gov/factsheets/Phosphorus-HealthProfessional

National Institutes of Health. (2021e). Selenium. https://ods.od.nih.gov/factsheets/Selenium-HealthProfessional

National Institutes of Health. (2021f). Vitamin C. https://ods.od.nih.gov/factsheets/VitaminC-HealthProfessional

National Institutes of Health. (2021g). Vitamin E. https://ods.od.nih.gov/factsheets/VitaminE-HealthProfessional

National Institutes of Health. (2021h). Vitamin K. https://ods.od.nih.gov/factsheets/vitaminK-HealthProfessional

National Institutes of Health. (2022a). Biotin. https://ods.od.nih.gov/factsheets/Biotin-HealthProfessional

National Institutes of Health. (2022b). Calcium. https://ods.od.nih.gov/factsheets/Calcium-HealthProfessional

National Institutes of Health. (2022c). Chromium. https://ods.od.nih.gov/factsheets/Chromium-HealthProfessional

National Institutes of Health. (2022d). Copper. https://ods.od.nih.gov/factsheets/Copper-HealthProfessional

National Institutes of Health. (2022e). Fluoride. https://ods.od.nih.gov/factsheets/Fluoride-HealthProfessional

National Institutes of Health. (2022f). Folate. https://ods.od.nih.gov/factsheets/Folate-HealthProfessional

National Institutes of Health. (2022g). Iodine. https://ods.od.nih.gov/factsheets/Iodine-HealthProfessional

National Institutes of Health. (2022h). Iron. https://ods.od.nih.gov/factsheets/Iron-HealthProfessional

National Institutes of Health. (2022i). Magnesium. https://ods.od.nih.gov/factsheets/Magnesium-HealthProfessional

National Institutes of Health. (2022j). Niacin. https://ods.od.nih.gov/factsheets/Niacin-HealthProfessional

National Institutes of Health. (2022k). Potassium. https://ods.od.nih.gov/factsheets/Potassium-HealthProfessional

National Institutes of Health. (2022l). Riboflavin. https://ods.od.nih.gov/factsheets/Riboflavin-HealthProfessional

National Institutes of Health. (2022m) Vitamin A. https://ods.od.nih.gov/factsheets/VitaminA-HealthProfessional

National Institutes of Health. (2022n). Vitamin B6. https://ods.od.nih.gov/factsheets/VitaminB6-HealthProfessional

National Institutes of Health. (2022o). Vitamin B12. https://ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional

National Institutes of Health. (2022p). Vitamin D. https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional

National Institutes of Health. (2022q). Zinc. https://ods.od.nih.gov/factsheets/Zinc-HealthProfessional

National Institute of Health. (2023a). Dietary supplements: What you need to know. https://ods.od.nih.gov/factsheets/WYNTK-Consumer

National Institutes of Health. (2023b). Omega-3 fatty acids. https://ods.od.nih.gov/factsheets/Omega3FattyAcids-HealthProfessional

National Institute of Health. (2023c). Thiamin. https://ods.od.nih.gov/factsheets/Thiamin-HealthProfessional

Natural Products Association. (n.d.). How dietary supplements (foods) become regulated. Retrieved April 5, 2023, from https://www.npanational.org/resource/dietary-supplements-foods-became-regulated

Nielsen, F. (2021). Nickel. Advances in nutrition, 12(1), 281-282. https://doi.org/10.1093/advances/nmaa154

Shane-McWhorter, L. (2023). Fish oil. Merck Manual Professional Version. https://www.merckmanuals.com/professional/special-subjects/dietary-supplements/fish-oil

Smith, R. (2004). Let food be thy medicine…. BMJ, 328(7433). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC318470/

Swan, J.P. (2015). The history of efforts to regulate dietary supplements in the USA. Drug Testing and Analysis, 8(3-4), 271-282. https://doi.org/10.1002/dta.1919.

US Department of Agriculture. (2020). Dietary guidelines for Americans 2020-2025. https://www.dietaryguidelines.gov/sites/default/files/2021-03/Dietary_Guidelines_for_Americans-2020-2025.pdf

US Food & Drug Administration. (2023). New dietary ingredients in dietary supplements: Background for industry. https://www.fda.gov/food/new-dietary-ingredients-ndi-notification-process/new-dietary-ingredients-dietary-supplements-background-industry#what_is

Venkatraman, S., & Dandekar, S. (2015). Nutrition and biochemistry for nurses (2nd ed.). Elsevier.

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