Vitamins

Vitamins

**Vitamins, Minerals, & Essential Fatty Acids**
Nutrient	Principle Sources	Functions	Deficicency Effects	RDS / Rx Dosage	Toxicity
Vit. A (retinol, retinoic acid)	fish, liver, liver oil, egg yolk, butter, cream, dark green leafy, vegetables, yellow fruits, red palm oil	prevents night blindness (Vision), epithelial inegrity; possible protection against epithelial cancers & atherosclerosis	night blindness; increased susceptibility to infection, xerophthalmia	RDA 5,000 IU (800-1000 ug) Rx: 30,000-60,000 IU/d	headache,cerebral edema, peeling of skin, hair loss, hepatotoxicity, bone thickening, yellowish skin, gingivitis, cheilosis, joint pain, teratogenicity
Vit. B₁ (thiamine)	dried yeast, whole grains, meat & liver, nuts, legumes, potatoes, enriched cereal products	carbohydrate metabolism, central & peripheral nerve cell function, myocardial function	Beriberi neuropathy & heart failure, Wernicke-Korsakoff synd.	RDA 1.2-1.5 mg/d Rx 5-25 mg/d x2wks	None
Vit. B₂ (riboflavin)	milk, cheese, liver, meat, eggs, enriched cereal products, dark green vegetables	energy & protein metabolism integrity of mucous membranes, cellular oxidation reduction reactions	stomatitis, dermatitis, anemia, cheilosis, corneal vascularization, amblyopia, sebacious dermatosis	RDA 1.3-1.7 mg/d Rx 10-30 mg/d x2wks	None
Vit. B₃ (niacin, nicotinic acid)	dried yeast, whole grains, meat & liver, legumes, enriched cereal products	oxidation reduction reactions, carbohydrate metabolism, reduces LDL, increases HDL; needed for healthy skin	Pellagra (dermatosis, glossitis, GI & CNS dysfunction)	RDA 13-19 mg/d Rx 300-500 mg/d x 4 wks	Flushing, headache, pruritus, hyperglycemia, hyperuricemiak hepatotoxicity
Vit. B₆ (pyridoxine)	dried yeast, liver, organ meats, fish, legumes, whole grian cereals	amino acid metabolism, heme synthesis; neuronal excitability, reduces blood homocysteine levels	anemia, cheilosis, dermatitis, neuropathy, seborrhea-like skin lesions, infant convulsion	RDA 1.6-2 mg/d Rx 50-100 mg/d x4wks	Neurotoxicity, headache, numbness, ataxia, sensory neuropathy
Vit. B₁₂ (cobalamin)	liver, meats, eggs, milk & milk products	DNA synthesis; myelin synthesis, RBC maturation, reduces blood homocysteine levels	Pernicious anemia, megaloblastic anemia, neuropathy	RDA 2 ug/d Rx 1 mg 2x/wk x 6wks; 1 mg IM/month	None
Vit. C (ascorbic acid)	citrus fruits, tomatoes, potatoes, cabbage, green peppers	collagen synthesis, essential to osteoid tissue, vascular function, tissue respiration, & wound healing, possible protection against certain neoplams	Scurvy (hemorrhages, loose teeth, gingivitis, bone disease)	RDA 60 mg/d Rx 100-500 mg/d	nephrolithiasis, diarrhea, nausea
Vit. D (calciferol) (Vitamin D Deficiency article)	ultraviolet light on skin, fish, liver, liver oils, butter, egg yolk, fortified milk	Ca & Phos GI absorption; resorption, mineralization & maturation of bone; tubular reabsorption of Ca	Osteomalacia & rickets, hypocalcemia	RDA 5 ug (200 IU) /d Rx 50-200 ug/d (2000-8000 IU/d) Vit. D3 x 3 wks	hypercalcemia, anorexia, renal failure, metastatic calcification
Vit. E (alpha-tocopherol)	vegetable oil, wheat germ, leafy vegetables, egg yolk, margarine, legumes	intracellular antioxidant, scavanger of free radicals in biologic membranes, reduces perosxidation of fatty acids; possible protection against atherosclerosis & dementia.	Rare; RBC hemolysis, neurologic damage; creatinuria, ceroid deposition in muscle	RDA 8-10 mg/d Rx 60-100 mg/d x 2 wks	interference with enzymes; antagonism of vit. K, possible headaches, blurred vision
Vit. K	leafy vegetables, pork, liver, vegetable oils, intestinal flora	synthesis of prothrombin, clotting factors VII, IX, X & possible V, & bone protein	Hemorrhagic diathesis; osteoporosis	RDA 65-80 ug/d Rx 10 mg/d x 10d	None
Folic acid	vegetables, legumes, grains, fruit, poultry, meat & liver, dried yeast	DNA synthesis, reduces blood homocysteine levels, maturation of RBC, synthesis of purines pyrimidines, & methionine	Pancytopenia, megaloblastic anemia, birth defects	RDA 200-400 ug/d Rx 1-2 mg/d x 4wks	None
Biotin	liver, kidney, egg yolk, yeast, cauliflower, nuts, legumes	amino acid & fatty acid metabolism, carboxylation & decarbosylation of oxaloacetic acid	Rare; dermatitis, glossitis, metabolic acidosis	RDA 30-100 ug/d Rx 150-300 ug/d x2wks	None
Pantothenic acid	many foods	metabolic processes	Rare	RDA 4-7 mg/d	None
Magnesium	green leaves, nuts, cereal grains, seafood	bone & tooth formation, nerve conduction, muscle contraction, enzyme activation	hypomagnesemia, hypocalcemia, neuromuscular irritability	Rx IM 2-4 mL 50% MgSO4 /day for several days	Hypermagnesemia, hypotension, resp. failure, cardiac disturbances, N& V, lethargy
Iron	beef, liver, kidney, soybean, flour, clams, peaches	Hgb & myoglobin formation, cytochrome enzymes, iron-sulfur proteins	iron deficiency anemia, dysphagia, koilonychia, enteropathy, impaired learning ability, decreased work performance.	Rx Ferrous sulfate 300 mg tid for 4-8 wks	Hemochromatosis, cirrhosis, diabetes, skin pigmentation, constipation or diarrhea
Zinc	meat,liver, eggs, oysters, peanuts, whole grains, variable in plant sources	skin integrity, wound healing, growth, component of enzymes	growth retardation, hypogonadism, hypogeusia, cirrhosis & acrodermatitis	Rx Zc-sulfate 30-150 mg/d x 6 months	nausea, diarrhea, interferes with copper absorption
Chromium	Brewer's yeast, liver, processed meats, whole grian cereals, spices	promotion of glucose tolerance	impaired glucose tolerance in malnourished children, some diabetics & elderly persons.	Rx Chromium chloride 200 ug/d x4wks	.
Selenium	wide distribution - meats & other animal products; variable in plants.	component of glutathione peroxidase & thyroid hormone iodinase	cardiomyopathy of Keshan disease, muscle weakness	Rx Na-selenite 100 ug/d	.
Manganese	whole grian cereals, green leafy vegetables, nuts, tea	component of certain enzymes	Primary deficiency is questionable. Secondary deficiency due to hydralazine: arthralgia, neuralgia, hepatosplenomegaly	Rx Manganese sulfate 10 mg/d x several wks	.
Phosphorus	meat products, tofu, milk	bone formation acid-base balance, cell membrane structure, component of ATP, CP, 2,3-DPG	.	.	.
Copper	lean beef & poultry	blood cell & connective tissue formation	.	.	.
Calcium	dairy products, canned salmon & sardines with bones	bone formation, enzyme activation, nerve impulse transmission, muscle contractions, cell membrane potential	.	.	.
Iodine	iodized salt, seafood, vegetables	helps in formation of thyroid hormones	.	.	.
.	.	.	.	.	.

Ref: The Merck Manual of Diagnosis and Therapy

Multivitamin/Mineral Supplements and Chronic Disease Prevention (in pdf format)

NIH State-of-the-Science Panel* 5 September 2006 | Volume 145 Issue 5 | Pages 364-371

What Is the Efficacy of Single Vitamin/Mineral Supplement Use in Chronic Disease Prevention?

Few high-quality clinical trials have been conducted to determine whether single-use or paired vitamins/minerals prevent chronic diseases, and even fewer are generalizable to the U.S. population. In addition, much of the evidence derives from post hoc analyses for outcomes not originally chosen as study end points. These studies are reviewed in the evidence report.

Findings by Vitamin/Mineral

ß-Carotene

Two large trials (1, 2) designed to test lung cancer prevention with ß-carotene found a surprising increase in lung cancer incidence and deaths in smokers and male asbestos workers. There was no effect in preventing a number of other types of cancer, including gastric, pancreatic, breast, bladder, colorectal, and prostate cancer as well as leukemia, mesothelioma, and lymphoma. The overall mortality rate was elevated in women, but not men, treated with ß-carotene throughout the intervention and postintervention period.

A third large trial (3), in healthy American men, found no effect of ß-carotene on cancer except an increased risk for thyroid and bladder cancer. Two other ß-carotene trials (4, 5) on prevention of nonmelanoma skin cancer found no effect on subsequent skin cancer incidence. A large study of healthy American women also found no effect of ß-carotene on cancer incidence (6). Four of these ß-carotene trials (2, 3, 5, 7) also evaluated cardiovascular disease (CVD) and found no benefits.
In healthy women, there was a suggestion of increased stroke risk in 1 study (6) and an increased risk for CVD in women smokers in the Carotene and Retinol Efficacy Trial (CARET) (8).

Vitamin A

No trials were found for vitamin A supplementation alone.
When vitamin A was paired with ß-carotene in 1 trial (2), lung cancer and CVD deaths were increased.
When vitamin A was combined with zinc in another trial, there was no impact on esophageal or gastric cardia cancer, although noncardia stomach cancer decreased (9).

Vitamin E

Four trials tested vitamin E. One large study of healthy women, the Women's Health Study (WHS), recorded decreased cardiovascular deaths, although there was no effect on incidence of CVD events (10).
Another trial found a decreased risk for prostate cancer (and a suggestion of decreased colorectal cancer risk) in male smokers, as well as a decreased risk for angina and thrombotic stroke (7, 11–14). No other effects were found on other types of cancer.
There was a trend toward increased bleeding, subarachnoid hemorrhage, and hemorrhagic stroke among male smokers in this study (7), but in the WHS, no increase in hemorrhagic stroke was seen among women (10).
Another trial (15) yielded inconclusive results for main cardiovascular end points because of small numbers and because the trial was stopped prematurely. Two trials examined development of age-related cataract (16) and lens opacity (14), respectively, and reported no effect of vitamin E supplementation.

Vitamin B2 and Niacin

One large Chinese trial of vitamin B2 and niacin found a decreased risk for nuclear cataracts (17). No effects were found on cortical cataracts, mortality rates, stroke, upper gastrointestinal dysplasia, or cancer.

Vitamin B6

Two small, short-duration studies of vitamin B6 to prevent cognitive decline in elderly men and women showed no effects (18).

Folic Acid with or without Vitamin B12

Multiple studies have shown the effectiveness of folic acid use by women of childbearing age to prevent neural tube defects in offspring. Four small, short-duration studies of folic acid, with or without vitamin B12, to prevent cognitive decline in older adults found no effects (19).

Selenium

Three trials tested selenium supplementation to prevent cancer. In 2 Chinese trials, selenium decreased liver cancer incidence in patients at high risk because of either a family history of liver cancer or hepatitis B exposure status (20). The reports of these trials, however, lack many important details.
The third selenium trial was conducted in men and women who had a history of skin cancer (21). It found no decrease in skin cancer but reported reductions in total deaths from cancer and in the incidence of lung, prostate, and colorectal cancer (outcomes the study was not designed to investigate).

Calcium and Vitamin D

Multiple studies demonstrate that calcium increases bone mineral density in postmenopausal women but by itself does not decrease fracture risk. Vitamin D alone does not increase bone mineral density or decrease fracture risk, but it does work in combination with calcium to decrease the risk for hip and nonvertebral fractures in postmenopausal women. Vitamin D and calcium may increase the risk for kidney stones. The single trial that tested the effect of calcium supplementation and vitamin D on colorectal cancer risk found no effect, but the doses may have been inappropriately low (22).

Summary

Few trials of individual or paired vitamins and minerals for the prevention of chronic disease produced beneficial effects. We found no evidence to recommend ß-carotene supplements for the general population and strong evidence to recommend that smokers avoid ß-carotene supplementation. In combination, calcium and vitamin D have a beneficial effect on bone mineral density and fracture risk in postmenopausal women.

On the basis of single studies and analysis of secondary outcomes, there is a suggestion that selenium may reduce risk for prostate, lung, and colorectal cancer; that vitamin E may decrease cardiovascular deaths in women and prostate cancer incidence in male smokers; and that vitamin A paired with zinc may decrease the risk for noncardia stomach cancer in rural China. Trials of niacin; folate; and vitamins B2, B6, and B12 produced no positive effect on chronic disease occurrence in the general population.

2006