Vitamins are organic compounds that an organism requires in small doses. In general, a vitamin is any compound necessary for life that cannot be synthesized by the organism. A compound can only be called a vitamin if it meets these two criteria:
1) The compound must have a known biological role and 2) the organism must lack the ability to produce it.
Vitamins are found in the body and in food, but they can be consumed by an organism only through their presence in food. The lack of one or more vitamins will eventually lead to a vitamin deficiency which can have negative health effects such as scurvy (lack of Vitamin C) or goitre (lack of Iodine).
Vitamins are essential to life and cannot be produced by an organism. They serve three main functions: Firstly, they help with certain chemical processes, for example Vitamin D is required for the body to absorb calcium. Secondly, they regulate metabolic pathways such as the breakdown and build-up of proteins. Thirdly, they help protect tissues and DNA from damage. Since we cannot produce some of these vitamins on our own, it is necessary to ingest them through food and supplements.
Vitamins have many functions in the body. Firstly they are utilised as coenzymes in various metabolic reactions such as the Krebs cycle. For example, Vitamin C is required to create collagen and amino acids for the body not only in bones but also blood vessels, tendons, ligaments and teeth. Vitamins are also important as regulators of vital metabolic pathways such as the maturation of red blood cells (B12) or carbohydrate metabolism (niacin). Furthermore, they protect the body from damage. For example Vitamin A is important in eyesight while Vitamin E protects cells from oxidation. Vitamins are required for tissues and bones to develop, function and repair themselves as well as protecting them against free radicals which can lead to cancer or aging.
The recommended daily intake of vitamins differs from person to person depending on age, gender and health. For example pregnant women require a higher dosage of folic acid in their diet which helps prevent neural tube defects. Vitamins are found in almost all food and can be divided into fat-soluble vitamins (A, D, E and K) which dissolve in fat and water-soluble vitamins (C and the B complex) which dissolve in water. The recommended daily amount of each vitamin is detailed in the table below:
In order to obtain these amounts through food, it has been found that between five and nine servings of fruit and vegetables are required every day. Unfortunately, most people only consume three to four servings a day. This means that it is more efficient to obtain vitamins through supplements which can be bought from any pharmacy or supermarket. When taking a supplement, it is important to avoid exceeding the recommended daily allowance as this can lead to vitamin toxicity and have adverse health effects.