What Are the Two Groups of Vitamins?

Vitamins are organic compounds your body needs in small amounts to function properly. You need to include a total of 13 vitamins, which fall into two categories based on how your body absorbs them, in your diet. The two major vitamin groups are fat-soluble vitamins and water-soluble vitamins.


Fat-Soluble Vitamins

Your body requires the presence of dietary fat in order to properly absorb the fat-soluble vitamins: A, D, E and K. When you consume these vitamins with fatty acids, they are carried into your lymphatic system where they circulate before entering the bloodstream. Your body has the ability to store excess amounts of fat-soluble vitamins in your fatty tissues and liver for use when your dietary intake falls short.

Water-Soluble Vitamins

The water-soluble vitamins dissolve in water when they enter the body and move into the bloodstream directly. The water-soluble vitamins consist of vitamin C and the B vitamins, which include thiamin, riboflavin, folate, niacin, pantothenic acid, biotin, vitamin B-6 and vitamin B-12. Your body uses these vitamins and then excretes excess amounts in your urine. With the exception of vitamin B-12, they cannot be stored for later use.

Toxicity and Deficiency

Because your body can store the fat-soluble vitamins, they pose a much greater risk for vitamin toxicity than the water-soluble vitamins. Few develop toxicities from high dietary intake of vitamins, which usually occurs as a result of excess vitamin supplementation. On the other hand, vitamin deficiencies are more common with the water-soluble vitamins, because your body cannot store them. Because of this, it is vital that you consume adequate amounts of the water-soluble vitamins through your diet on a daily basis. Fat-soluble vitamin deficiencies are possible, but they are usually a result of underlying illnesses that decrease your ability to absorb fat, thus decreasing your ability to absorb the vitamins.


Water-soluble vitamins are also more unstable than the fat-soluble vitamins. Many of the water-soluble vitamins in the food you eat are easily destroyed by exposure to air and excess heat, and they are all subject to being washed out by water. It is important to use extra care when storing, preparing and cooking any foods that are high in water-soluble vitamins to avoid significantly reducing or destroying the vitamin content of these foods. The Colorado State University Extension recommends refrigerating fresh produce, protecting milk and grains from exposure to bright light and lowering cooking temperatures to preserve the water-soluble vitamins in foods. Exposure to air, water and heat will not destroy fat-soluble vitamins.

  • "Nutrition and You"; Joan Salge Blake; 2008

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