The source of a vitamin deficiency is generally lack of nutrition, disease or a malabsorption syndrome. A functional deficiency often results in a list of issues from muscle weakness to poor eyesight to irreversible damage, disease and sometimes death.
Vitamin A
Vitamin A, a fat-soluble vitamin is present in supplements and found only in foods of animal origin, but its active precursor, beta-carotene, is present in fruits and vegetables. Vitamin A is stored in the liver and kidneys. Sources of deficiency include a poor diet, liver or kidney disease. A functional deficiency includes viral and respiratory infections, scaly skin and scalp, poor eyesight, burning, itching and dry eyes. These deficiencies can result in night blindness, kidney stones, mild skin conditions and inflamed mucous membranes.
Biotin
Biotin, a water-soluble vitamin and member of the vitamin B complex, can be found in wheat germ, wheat bran, dried brewer's yeast, eggs, fish, rice, vegetables and yeast extract. As a water-soluble vitamin, only small amounts of biotin remain in the body at any given time, with the excess released in the urine. Two sources of deficiency include taking antibiotics and stress. Giving infants unfortified dried milk can also cause a deficiency, resulting in a dry face and scalp and persistent diarrhea. For adults, a deficiency can cause fatigue, depression, nausea, loss of appetite and hair loss.
Vitamin C
Vitamin C, a water-soluble vitamin, functions to maintain healthy bones, teeth, blood and sex organs, and it also acts as a natural antihistamine. A functional deficiency causes scurvy, weakness, muscle and joint pain, bleeding gums and hemorrhages in the skin, eyes and nose. Sources of vitamin C deficiency include a diet lacking in fresh fruits and vegetables.
Vitamin D
The majority of vitamin D production occurs from the skin by the action of sunlight. Vitamin D supports the absorption of calcium and phosphate from food. A functional deficiency can result in rickets in children and osteomalacia in adults. In both children and adults, the deficiency results in the softening of bones due to a lack of calcium phosphate. The source of a deficiency is most often a diet lacking in meat, poultry, fish and dairy products, and a lack of exposure to the sun. When sun exposure is sufficient, dietary support for this vitamin is not necessary.
References
- National Institutes of Health Office of Dietary Supplements: Vitamin A and Carotenoids
- Medline Plus: Biotin
- National Institutes of Health Office of Dietary Supplements: Vitamin C
- National Institutes of Health Office of Dietary Supplements: Vitamin D
- Oregon State University, Linus Pauling Institute: Vitamins
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