What Vitamins Are Essential?

An essential nutrient is one that is necessary for health, cannot be made by the body in adequate amounts, and therefore must be obtained from the diet. Lack of a vitamin will cause a specific deficiency disease. The vitamins that have been discovered to be essential include Vitamins A, B complex (referring to a group of B vitamins), C, D, E and K.

Classifying Vitamins

Vitamins are classified into two major groups: those that are soluble in fat and those that are soluble in water. The former group includes vitamins A, D, E and K. Fat soluble vitamins are stored in the body tissues and organs, particularly the liver. This means they do not have to be consumed every day as they are not regularly excreted.
Water soluble vitamins are the B complex vitamins (including thiamin, riboflavin, niacin, folate, pantothenic acid, biotin, Vitamin B6 [pyridoxine] and Vitamin B12 [cobalamin]) and Vitamin C. These are stored in smaller amounts and for shorter periods of time compared to fat soluble vitamins, so must generally be consumed on a daily basis.

Vitamin Functions

Vitamins assist in numerous biochemical and physiological processes in the body. Each vitamin has a unique role. Many of the B complex vitamins assist in obtaining energy (calories) from food. The need for these vitamins is higher with an increased protein or carbohydrate intake in the diet. Other vitamins help maintain healthy skin or membranes (A and C), a healthy digestive system (niacin, riboflavin and Vitamin A), proper night vision (Vitamin A), strong bones (Vitamin D), or red blood cells that carry oxygen as needed (folate, Vitamin B12 and Vitamin E). Vitamin K helps blood clot when bleeding occurs, such as a cut or an ulcer.

Deficiency Diseases

Symptoms of a deficiency disease will appear when adequate amounts of any vitamin are not present. Over a period of time, some organ, tissue or process in the body will not function or form well. For example, a change in appearance of the eyes, skin, lips or gums may indicate a lack of Vitamin A, C or riboflavin. Several vitamin deficiencies lead to different forms of anemia. In this disease, red blood cells may become too small, too sparse, or even break open, resulting in symptoms, such as weakness, exhaustion and shortness of breath due to inadequate oxygen supply to body cells. Lack of vitamins in childhood will retard growth because tissues are not formed properly; an example is weakly formed leg bones which bow under the weight of the child when Vitamin D is lacking in the diet. This disease is called Rickets. Eventually, lack of any vitamin will lead to a condition severe enough to cause extreme damage in some function or area of the body, and often result in death.