There seem to be so many vitamins that it can be hard to keep track of which one is which. In short, vitamins are essential for the healthy function of our bodies. As the body does not synthesise vitamins itself they must be consumed as part of a balanced diet. Vitamins have been described as “organic compound(s) required as a nutrient in tiny amounts by an organism”1.
As previously mentioned, our diets are one of the few sources of vitamins for our bodies. These vitamins appear in a whole variety of foods, such as fruits, vegetables, cereals, and many others too. Some types of vitamins, such as vitamin D, are obtained by the body in other ways; in this example, it is ultraviolet light. Aside from food and sunshine, vitamins are available in supplement or powder form too, and may be ideal for those who struggle to get a healthy amount of nutrients in their diets.
In humans there are 13 vitamins, 9 are water-soluble (8 B-vitamins, C) and 4 are fat-soluble (A, D, E, K)2. Water-soluble vitamins, which are nine of the 13 types found in humans (8 B-vitamins, vitamin C), are excreted in the urine; therefore they need to be replenished frequently. The other four vitamins (A, D, E, K) are fat soluble, so they require fats and minerals to be stored in the liver3.
In alphabetical order, here is a list of the vitamins A- K and the functions they perform4:
- Vitamin A is fat soluble and is key for maintaining a health eyesight, and growth.
- Vitamin B1 (Thiamine) is water soluble and is important for healthy skin, blood, hair, muscles, brain and nervous function.
- Vitamin B2 (Riboflavin) is associated with hormone function, as well as the benefits of Thiamine.
- Vitamin B3 (Niacin) is essential for the repair of genetic material as well benefits seen in Thiamine.
- Vitamin B5 (Pantothenic acid) is needed for the metabolism of cholesterol and fatty acids.
- Vitamin B6 (Pyridoxine) is used to maintain cardiovascular health and nervous and immune systems.
- Vitamin B7 (Biotin) is required for protein metabolism, manufacture of genetic material.
- Vitamin B9 (Folic Acid) is commonly known for the use for healthy pregnancies.
- Vitamin B12 (Cobalamin) is needed for amino acid and fatty acid metabolism.
- Vitamin C can help to stave off common colds, and may boost the immune system.
- Vitamin D is important for maintaining calcium levels in the blood.
- Vitamin E is a powerful antioxidant, which helps to fight the toxins in the body.
- Vitamin K is used by the body for blood clotting, as well as bone metabolism and kidney function.
Sources  Lieberman, S, Bruning, N (1990). The Real Vitamin & Mineral Book. NY: Avery Group, 3.  Wikipedia (2009). Vitamin. http://en.wikipedia.org/wiki/Vitamin  The Vitamin Update (2009). What are Vitamins? http://www.vitamin-update.com/vitamins.cfm
 Netdoctor (2007). Vitamins and minerals – what do they do? http://www.netdoctor.co.uk/health_advice/facts/vitamins_which.htm