Vitamins

Water Soluble Vitamins

Vitamin

Disease States

B1 (thiamine)
Catalyzes reactions that produce energy

Sources – legumes, nuts, whole grains
Inhibitors – alcohol, coffee, loop diuretics, raw fish, shellfish, tea

Vitamin B1 deficiency
Mainly found in alcoholics in U.S.
Wet beriberi – high-output cardiac failure
Dry beriberi – symmetrical peripheral neuropathy
Wernicke encephalopathy

Beriberi combined with alcoholism
Horizontal nystagmus, ophthalmoplegia, cerebellar ataxia, mental impairment

Wernicke-Korsakoff syndrome

Coexistence of additional loss of memory and confabulatory psychosis

Vitamin B1 toxicity – rare reports of anaphylaxis

B2 (riboflavin)
Catalyzes reactions that produce energy; coenzyme in the flavoproteins that participate in tissue oxidation and respiration processes

Sources – broccoli, eggs, enriched breads, fish, lean meats, legumes, milk, other dairy products
Inhibitors – sunlight rapidly degrades the vitamin in foodstuffs

Vitamin B2 deficiency
Mucocutaneous lesions including magenta tongue, angular stomatosis, seborrhea, cheilosis

Vitamin B2 toxicity
None reported; gastrointestinal tract can only absorb limited quantities

B3 (niacin)
Catalyzes the metabolism of fatty acids, amino acids and carbohydrates

Sources – beans, eggs, meat, milk
Inhibitors – B2 or B6 deficiency reduces conversion of tryptophan to niacin; drugs that may interfere with metabolism include alcohol, amitriptyline, chlorpromazine, imipramine

Vitamin B3 deficiency
Mainly found in alcoholics in U.S.

Can occur in carcinoid and Hartnup diseases

Pellagra
Pigmented rash in sun-exposed areas (Casal necklace), bright red tongue, diarrhea, apathy
As drug therapy, flushing and headache frequently accompany treatment doses

Vitamin B3 toxicity
Hepatotoxicity is most serious problem
Glucose intolerance, macular edema, macular cysts

B5 (pantothenic acid)
Functions in the metabolism and biosynthesis of many compounds

Sources – broccoli, egg yolk, liver, yeast
Inhibitors – none

Vitamin B5 deficiency
Deficiency has only been demonstrated experimentally; may have caused burning feet syndrome in prisoners
Gastrointestinal disturbance, depression, paresthesias, ataxia, hypoglycemia

Vitamin B5 toxicity – none reported

B6 (pyridoxine)
Coenzyme in transaminase reactions

Sources – legumes, meats, nuts, wheat bran
Inhibitors – drugs such as cycloserine, isoniazid,  L-dopa, penicillamine

Vitamin B6 deficiency
Seborrhea, glossitis, convulsions, neuropathy, depression, confusion, microcytic anemia

Vitamin B6 toxicity – severe sensory neuropathy

B7 (biotin)
Coenzyme in transfer of carbonyl groups

Sources – beans, egg yolks, liver, soy, yeast
Inhibitors – egg whites

Biotin deficiency
Only demonstrated in patients with short bowel syndrome receiving total parenteral nutrition
Adults – mental status changes, anorexia, nausea, seborrheic rash
Infants – hypotonia, lethargy, apathy, alopecia and rash on ears

Biotin toxicity – None reported

Folate (B9, folic acid, folacin)
Coenzyme in metabolic reactions

Sources – fortified breads, cereals and grain products, fruits, leafy vegetables, organ meats, yeast
Inhibitors – anticonvulsants, chemotherapy agents, malabsorptive disorders (sprue), methotrexate

Folate deficiency
Megaloblastic anemia – no neurologic symptoms
Fetal open neural tube defects
May be related to increased development of certain cancers

Folate toxicity – none reported

B12 (cobalamin)
Cofactor for enzymatic reactions, metabolism of odd chain fatty acids, and methylation of homocysteine

Sources – animal products, dairy products
Inhibitors – achlorhydria, H2 receptor antagonists, overgrowth of intestinal organisms (eg, short bowel syndrome), proton-pump inhibitor drugs

Vitamin B12 deficiency
Deficiency found in ~30% of people >60 years.
Megaloblastic (macrocytic) anemia
Neurologic manifestations – loss of vibratory and position sense, abnormal gait, dementia, depression, loss of bowel and bladder control

Vitamin B12 toxicity – none reported

C (ascorbic acid)
Coenzyme in formation of collagen and synthetic reactions
Has antioxidant activity and is a free radical scavenger

Sources – citrus fruits, green vegetables, potatoes, tomatoes
Inhibitors – smoking, hemodialysis

Vitamin C deficiency
Scurvy – bleeding into skin, inflamed and bleeding gums, bleeding into joints, impaired bone growth

Vitamin C toxicity – elevated liver enzymes, abdominal pain, diarrhea

Vitamin

Disease States

A (retinol)
Required for normal vision, growth and differentiation of epithelial tissue as well as bone growth, immunity, reproduction and embryonic development

Sources – beef, egg yolk, fish, liver, vegetables
Inhibitors – ethanol, mineral oil, neomycin, cholestyramine

Vitamin A toxicity
Acute – increased intracranial pressure, vertigo, diplopia, seizures
Chronic – cheilosis, glossitis, alopecia, bone pain, hyperlipidemia, liver fibrosis

Sources – dairy, egg yolks,fish oils, fortified foods; also synthesized in response to ultraviolet radiation
Inhibitors – barbiturates, isoniazid, phenobarbital, phenytoin, rifampin, sunblock

Vitamin D toxicity
Rare; associated with ≥10,000 IU/day intake (Not seen until 25(OH)D ≥150 ng/mL

Sources – sunflower oil, safflower oil, wheat germ, soybean
Inhibitors – none

Vitamin E toxicity
Reduced platelet aggregation, interference with warfarin treatment

Sources – butter, coffee, egg yolk, green leafy vegetables, ground beef, milk, pears
Inhibitors – broad spectrum antibiotics, warfarin

Vitamin K toxicity
Infants – hemolytic anemia and hypobilirubinemia