Dietary Supplements Nursing CE Course

Period

Significant Event

400 BCE

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

1500s

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

1747

Dr. James Lind performed the first nutritional experiment and identified scurvy’s cause as vitamin C deficiency.

1800s

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

1840

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

1897

Christiaan Eijkman discovered the cause of beriberi, vitamin B1 (thiamine).

1912

E. V. McCollum discovered the first fat-soluble vitamin, vitamin A.

1913

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

1930s

William Rose discovers essential amino acids.

1940s

Water-soluble vitamins B and C were identified.

1950s

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

1968

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 United States, 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 United States and equally common around the world.

1950s-1970s

Malnutrition and vitamin deficiencies significantly decline, but diet-related noncommunicable diseases (cardiovascular disease [CVD], obesity, and type 2 diabetes mellitus [T2DM]) increase. This leads to focusing on micronutrients and supplements for pregnant females and children.

1980s-2010s

Between 1999 and 2012, almost 52% of adults reported using supplements, reflecting an overall increase from the 1980s of around 40%. However, the use of multivitamins/multiminerals decreased, with vitamin D, lycopene, and omega-3 fatty acid supplementation increasing.

2020s

An increase was reported in the overall use of dietary supplements from 51.8% in 2011-2012 to 61.4% by 2021-2023. 10 supplements have increased in use: biotin, vitamins B1 and 12, C, and D, zinc, coenzyme Q10, fiber, ginger, and probiotics. The most significant growth was with fiber and probiotic use.

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, 2024; NIH, 2025g)

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, 2024; 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 females and their infants
• individuals with Infantile Brown-Vialetto-Van Laere or Fazio-Londe syndrome (Johnson, 2024; NIH, 2022g)

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 females

Drug interactions include:

• isoniazid and pyrazinamide, parts of rifampin/isoniazid/pyrazinamide (Rifater)
• antidiabetic medications
• statins

At-risk populations for deficiency include:

• individuals with anorexia, HIV/AIDS, AUD, inflammatory bowel disease (IBD), liver cirrhosis, Hartnup disease, or carcinoid syndrome (Johnson, 2024; NIH, 2022e; UpToDate Lexidrug, n.d.)

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, 2024; NIH, 2023d)

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 (a 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
• females of childbearing age
• pregnant individuals (Johnson, 2024; NIH, 2022d)

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, 2024; NIH, 2025h)

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 (cyclophosphamide [Cytoxan], chlorambucil [Leukeran], carmustine [BiCNU], busulfan [Busulfex], thiotepa [Tepadina], 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 patients who have undergone bariatric surgery
• patients with end-stage renal disease (ESRD) on hemodialysis or cancer (Johnson, 2024; NIH, 2025i)

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, 2024; NIH, 2025j)

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 1,500 g
• those with a fat malabsorption disorder (IBD, cystic fibrosis, celiac disease, or liver disease), obesity, or a history of bariatric surgery (Johnson, 2024; NIH, 2021d)

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 (cholestyramine [Questran] 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, 2024; NIH, 2021e)

Vitamin

Males aged 18+

Females aged 18+

Pregnancy

Lactating

Vitamin A 

900 mcg RAE

700 mcg RAE

770 mcg RAE

1,300 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 NE

14 mg NE

18 mg NE

17 mg NE

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

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 females
• individuals who do not consume dairy products (Johnson, 2025; NIH, 2025a)

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 (cimetidine [Tagamet] or famotidine [Pepcid])
• proton pump inhibitors (omeprazole [Prilosec] or pantoprazole [Protonix])

Increased effects of chromium may be experienced if taken with:

• atenolol (Tenormin)
• propranolol (Inderal)
• insulin
• niacin
• NSAIDs (ketorolac [Toradol], ibuprofen [Motrin, Advil], or aspirin [Ecotrin]) (Johnson, 2025; NIH, 2022b)

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, 2025; NIH, 2022c)

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 (well water)

Fluoride deficiency can result in weak bones (osteoporosis) and teeth (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, 2025; NIH, 2025b)

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 who do not use iodized salt or live in an area with iodine-deficient soil, pregnant individuals, 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 (benazepril [Lotensin] or lisinopril [Prinivil])
• potassium-sparing diuretics such as spironolactone (Aldactone; Johnson, 2025; NIH, 2024)

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:

• females (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, 2025; NIH, 2025c)

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, and T2DM
• 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, 2026a)

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 males or increased premenstrual pain, altered mood, or osteoporosis in females

Symptoms of manganese toxicity include:

• central nervous system depression, tremor, tinnitus, hearing loss, muscle 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, 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, 2025; NIH, 2021a, 2021b)

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 (DNA, 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 (Maalox HRF, Rulox) bind phosphates in the intestines and can lead to hypophosphatemia
• antacids containing calcium carbonate (Rolaids, Tums, Maalox) decrease the intestinal absorption of dietary phosphorus
• enema preparations (Fleet) may contain sodium phosphate, which can increase serum phosphorus levels (NIH, 2023b)

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 (benazepril [Lotensin]), angiotensin receptor blockers (ARBs; 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, 2022f)

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 ( cancer, cognitive decline, thyroid disease, 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 (clopidogrel [Plavix], enoxaparin [Lovenox], warfarin [Coumadin])
• cholesterol-lowering medications (lovastatin [Mevacor], pravastatin [Pravachol])
• barbiturates
• oral contraceptives (ethinyl estradiol/levonorgestrel [Triphasil], ethinyl estradiol/norethindrone [Ortho-Novum]; Johnson, 2025; NIH, 2025f)

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, 2025; Estilo et al., 2021; Sterns & Hoorn, 2026)

Sulfur/sulfate is involved in the process of protein turnover in the body and in the biosynthesis of essential compounds in the body.

Inadequate intake can cause stunting of growth (rare).

Individuals at risk for excessive sulfur/sulfate: Those with renal failure can have increased serum sulfate levels up to 24 times the normal and may require hemodialysis to be removed in end stages.

RDAs are not established because sulfate deficiency is rare due to its abundance in food and water sources (Institute of Medicine [IOM], 2005b).

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 for 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 United States, but at-risk groups include:

• those with inadequate intake, such as vegetarians, pregnant or lactating individuals, 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 to 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, 2025; NIH, 2026b)

Mineral

Males aged 18+

Females aged 18+

Pregnancy

Lactation

Calcium

1,000 mg

1,000 mg

1,000 mg

1,000 mg

Chloride

1.8-2.3 g/day

1.8-2.3 g/day

2.3 g/day

2.3 g/day

Chromium

35 mcg

25 mcg

30 mcg

45 mcg

Copper

900 mcg

900 mcg

1,000 mcg

1,300 mcg

Fluoride

4 mg

3 mg

3 mg

3 mg

Iodine

150 mcg

150 mcg

220 mcg

290 mcg

Iron

8 mg

18 mg

27 mg

9 mg

Magnesium

400–420 mg

310–320 mg

350–360 mg

310–320 mg

Manganese

2.3 mg

1.8 mg

2.0 mg

2.6 mg

Molybdenum

45 mcg

45 mcg

50 mcg

50 mcg

Nickel

n/a

n/a

n/a

n/a

Phosphorus

700 mg

700 mg

700 mg

700 mg

Potassium

3,400 mg

2,600 mg

2,900 mg

2,800 mg

Selenium

55 mcg

55 mcg

60 mcg

70 mcg

Sodium

1,500 mg

1,500 mg

1,500 mg

1,500 mg

Sulfur

n/a

n/a

n/a

n/a

Zinc

11 mg

8 mg

11 mg

12 mg

Dietary Supplement and Dosing Information

Potential Indications

Nursing Implications/Alerts

Black cohosh

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

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 (breast; NIH, 2020a)

Echinacea

• dosing ranges from 2,400 to 4,000 mg/day

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 (NCCIH, 2024)

Garlic

• 1,000–7,200 mg/day for hyperlipidemia

300–1,500 mg/day for hypertension

1 mg/kg/day 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 (saquinavir [Invirase], ritonavir [Norvir]) (NCCIH, 2025a)

Ginkgo biloba

• dosing ranges from 120 to 240 mg/day

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, 2025b)

Saw palmetto

• doses range from 160 to 230 mg/day

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, 2025c)

St. John’s wort

• dosing ranges from 750 to 900 mg/day

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

interacts with numerous medications, including antiretroviral drugs, chemotherapeutics (irinotecan hydrochloride [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, 2025d)

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/day

• phenylalanine can function 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/day

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

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

20 mg/kg/day

• 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/day

• 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/day

• can be used to treat patients with liver disease, viral infection, AUD, pancreatitis, depression, allergies, asthma, radiation adverse 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/day

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

Isoleucine induces muscle protein synthesis.

19 mg/kg/day

• 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/day

• 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/day

• 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/day

• 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.

2,000–3,000 mg/day

• used in the treatment of hypertension, angina, peripheral artery disease, and erectile dysfunction
• may interact with medications (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.

2,000 mg/day for 7 days, then 3,000 mg before exercise; 1,000 mg/day 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.

500–2,000 mg/day in most adults;

up to 7,600 mg/day 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.

1,500–6,000 mg/day

• 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

Dietary Supplement

Role

RDA

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 (CFUs) in 3–4 divided doses

Common adverse 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.

Role

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 g in adolescents/adults.

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

Adverse 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