Vitamins are essential nutrients the body cannot produce, but needs in small amounts for health and development. Vitamins do not supply the body with energy, but instead perform several roles in keeping the body working and protecting you from disease. They can be classified as either water- or fat-soluble.
Definition
Vitamins are organic substances, meaning they contain carbon, and are made by plants and animals. As defined in the Internet Journal of Nutrition and Wellness, a vitamin is an "organic chemical required in small amounts for complete health and well-being," of which a "deficiency causes a well-defined disease that is prevented or cured by the appropriate vitamin."
Water-Soluble Vitamins
Vitamin C and the B-complex vitamins -- cobalamin (B12), pyridoxine (B6), biotin (B7), niacin (B3), thiamine (B1), riboflavin (B2), folic acid (B9) and pantothenic acid (B5) -- are all water-soluble vitamins. As they're not stored in the body, it is necessary to include them in your diet more frequently. Your body protects itself from harmful levels of these vitamins by excreting excess amounts in urine.
Water-soluble vitamins easily dissolve in water. They can be lost in water used for cooking and be destroyed by high cooking temperatures and exposure to air. Minimizing cooking techniques, such as boiling, and choosing instead to steam or grill your foods can help retain these vitamins.
Fat-Soluble Vitamins
Vitamins A, D, E and K are fat-soluble. These vitamins differ from water-soluble vitamins in that they require a source of dietary fat, such as vegetable oils, oily fish or animal fats to be present for your body to effectively absorb and use them. They are also less susceptible to cooking methods, and unlike water-soluble vitamins, fat-soluble vitamins can be stored in large amounts by the body. For this reason, it is not recommended to consume high levels as they can be harmful, resulting in health problems and even toxicity if the body absorbs too much.
Roles and Functions
Vitamins play several key roles within the body. For example, Vitamins B1, 2 and 3 help you produce energy, while vitamin B6 and biotin help the body use protein. Vitamin B6 also helps to form hemoglobin, an important carrier of oxygen in the blood. Others, such as vitamins A, D and E, have roles in promoting healthy growth and development, fighting off infections and damage to cells, as well as keeping your immune system strong. All vitamins are essential for maintaining good health.
References
- Food Standards Agency: What are vitamins?
- CDC: Vitamins and Minerals
- Internet Journal of Nutrition and Wellness: "Vitamins: Issues of definition and regulation"; Gareth Morgan; 2009; Vol 7, No 1
- eMedicine by Medscape: Vitamin A Toxicity
- Dietitians of Canada: Functions and Food Sources of Some Common Vitamins
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