Vitamins are required in the diet since they are not adequately synthesized in the human body.
- Only small amounts are necessary to catalyze the essential biochemical reactions
- Deficiencies are rare in healthy patients in the U.S.
- Exception is in gastric bypass patients
- Disease states generally result from poor diet
- Body stores vary by vitamin
- Thiamine (B1) and folate stores are small and rapidly depleted
- Cobalamin (B12) stores are large
- Vitamins play several roles in disease processes
- Diseases can cause vitamin deficiency
- Vitamin deficiency or excess can cause disease
- High doses of certain vitamins can be used to manage some diseases
| Water Soluble Vitamins | |
Vitamin | Disease States |
B1 (thiamine) Sources — legumes, whole grains, nuts | Vitamin B1 deficiency Mainly found in alcoholics in U.S. Wet beriberi — cardiac high output failure Dry beriberi — symmetrical peripheral neuropathy Wernicke encephalopathy Beriberi combined with alcoholismWernicke-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 — milk, dairy products, enriched breads, lean meats, fish, eggs, broccoli, legumes | Vitamin B2 deficiency Mucocutaneous lesions including magenta tongue, angular stomatosis, seborrhea, cheilosis Vitamin B2 toxicity |
| B3 (niacin) Catalyzes the metabolism of fatty acids, amino acids and carbohydrates Sources — beans, milk, meat, eggs | Vitamin B3 deficiency Pellagra Mainly found in alcoholics in U.S. Can occur in carcinoid, Hartnup disease 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 |
| B5 (pantothenic acid) Functions in the metabolism and biosynthesis of many compounds Sources — liver, yeast, egg yolk, broccoli | 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, nuts, wheat bran, meats | Vitamin B6 deficiency Seborrhea, glossitis, convulsions, neuropathy, depression, confusion, microcytic anemia Vitamin B6 toxicity — severe sensory neuropathy |
| Folate Coenzyme in metabolic reactions Sources — fruit, leafy vegetables, yeast, organ meats | Folate deficiency Megaloblastic anemia Fetal open neural tube defects No neurologic symptoms 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 | Vitamin B12 deficiency Megaloblastic (macrocytic) anemia Neurologic manifestations — loss of vibratory and position sense, abnormal gait, dementia, loss of bowel and bladder control Vitamin B12 toxicity — none reported |
| Biotin Coenzyme in transfer of carbonyl groups Sources — liver, soy, beans, yeast, egg yolks | Biotin deficiency Only demonstrated in patients with short bowel syndrome receiving total parenteral nutrition Biotin 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, tomatoes, potatoes | 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 |
| Fat Soluble Vitamins | |
Vitamin | Disease States |
A (retinol) Sources — vegetables, liver, fish | Vitamin A deficiency Ophthalmic — xerophthalmia, Bitot spots, corneal ulcers Dermatologic — Hyperkeratotic skin lesions Vitamin A toxicity |
| D (calcitrol) Hormone precursor Required for calcium absorption, bone metabolism, regulation of cell development and the immune system Sources — dairy, fish oils, egg yolks, also synthesized in response to ultraviolet radiation | Vitamin D deficiency Children — rickets and rachitic rosaries (expansion of growth plate) Adults — osteomalacia Hypocalcemia and hypophosphatemia with impaired mineralization of bone matrix Vitamin D toxicity |
| E (tocopherol) Coenzyme in formation of collagen, synthetic reactions, antioxidant activity and free radical scavenger Sources — sunflower oil, safflower oil, wheat germ, soybean | Vitamin E deficiency Almost exclusively in severe and prolonged malabsorptive disorders Peripheral neuropathy — areflexia, ataxia, ophthalmoplegia, skeletal myopathy Vitamin E toxicity — reduced platelet aggregation, interference with warfarin treatment |
| K (phylloquinone, menaquinone) Essential for carboxylation of glutamic acid residues and some proteins Sources — green leafy vegetables, butter, milk, ground beef, coffee, pears | Vitamin K deficiency Hemorrhage of mucous membranes and gastrointestinal tract Vitamin K toxicity |
