Food performs many functions, but the most basic function of food is to supply the nutrients your body needs to sustain your physical existence. Many of the nutrients in foods exist as vitamins, essential substances your body needs to maintain the heart, lungs, circulatory system and other functions. However, overdosing on vitamin supplements can have adverse health effects. Consult your physician before taking any vitamin supplements.
Water-Soluble Vitamins
Water-soluble vitamins do not accumulate in the body. They dissolve in water and what the body does not use right away passes through the digestive system through urine. As a result, humans need to intake water-soluble vitamins each day. Water-soluble vitamins include vitamin C and the B-complex vitamins, including thiamine, riboflavin and niacin. Vitamin C is plentiful in fresh fruits, especially citrus fruits. Vitamins from the B-complex family are found in foods ranging from grains, fish and meats to legumes and fresh vegetables. Nutrients from water-soluble vitamins are easily lost through washing and food preparation, according to the Colorado State University Extension website. Taking mega-doses of water-soluble vitamins is not advisable.
Fat-Soluble Vitamins
Fat-soluble vitamins dissolve in fat before being absorbed into the bloodstream. What the body does not use right away collects in fatty body tissues and in the liver. Deficiencies of fat-soluble vitamins are rare in the U.S., according to the Colorado State University Extension website. Vitamins A, D, E and K are fat-soluble vitamins. Vitamin A is found in a number of foods, including whole milk, liver, leafy green vegetables and egg yolks. Dairy foods are a major source of Vitamin D, along with fish oils. Vitamin E comes from vegetable oils, butter and margarine, nuts and whole grains, among other sources. Liver and dark, leafy green vegetables also provide Vitamin K. Because fat-soluble vitamins collect in the body, mega-doses can be toxic.
Vitamins Produced in Body
The body is unable to produce most of the vitamins it needs; they must come from food or supplements. However, two important exceptions exist. Exposure to the sun stimulates the production of vitamin D through the surface of your skin. Most people only need about 10 to 20 minutes of exposure to sunlight three times per week, according to website Disabled World. Dark-skinned people might need more exposure because of increased levels of melanin in their skin. Bacteria in the large intestine enable the body to produce Vitamin K, Top Form Supplements and Disabled World say.
Vitamin Overdose
Most healthy people who eat a nutritionally-balanced diet do not need to take vitamin supplements. However, taking a multivitamin or even a specific vitamin supplement can be beneficial in some cases. Nonetheless, taking more than the recommended dosage of a vitamin supplement can produce side effects, some of which can be serious or even life threatening. Among the most serious side effects from vitamin overdose include convulsions, irregular heartbeat, central nervous system damage, blurred vision and muscle weakness. Most often, these symptoms occur in people taking vitamin mega-doses of fat-soluble vitamins. However, relatively low levels of Vitamin E can trigger symptoms of toxicity, the American Pregnancy Association says.
References
- Colorado State University Extension; "Water-Soluble Vitamins"; J. Anderson et al; May 2010
- Colorado State University Extension; "Fat-Soluble Vitamins"; J. Anderson et al; May 2010
- Disabled World; "What are Vitamins and Minerals?"; October 2007
- Office of Dietary Supplements: Vitamin A and Carotenoids
- American Pregnancy Assocation; "Symptoms of Overdose"; 2011
- Topform Nutrition Supplement; "Vitamin K"; 2010
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