Vitamin Classification
Vitamins are classified into two groups; water-soluble and fat-soluble. Letters, groups, and individual chemical names further categorize vitamins.
Water-soluble Vitamins
Water-soluble vitamins that are stable in raw foods can be lost easily while cooking and processing. Water-soluble vitamins are readily available in vegetables and fruits, but less so in most animal sources. Water-soluble vitamins are generally not stored in the body and are excreted within four hours to one day. This means regular consumption critical. However, this also means the potential for toxicity, due to excessive intake, is very low. The function of most water-soluble vitamins is to act as coenzymes that combine with an inactive protein, which then becomes an active enzyme.
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Fat-soluble Vitamins
The fat-soluble vitamins are found in the lipid (fat) component of both vegetable and animal sources. They are vitamins A, D, E, and K. Vitamin A can also be converted from its precursor beta-carotene, an orange pigment found in many vegetables. Fat-soluble vitamins can be stored in body tissues enabling normal function for longer time periods between obtaining them from the diet. This storage capacity can also allow toxic levels to potentially build up. This is especially true for vitamin A, D, and K. Vitamin E toxicity is less likely since it is used throughout the body as an antioxidant to help protect from the harmful side effects of oxidation and outside pollutants.