Dear Dr. Gott: I am deficient in B12 and get a shot monthly. Therefore, I am interested in information on vitamins in general.

Reply: There are 13 vitamins that your body needs, all essential for maintaining good health.

These are broken down into two categories, water soluble and fat soluble.

The water-soluble vitamins include the B complex, which is comprised of eight vitamins – 1, 2, 3, 5, 6, 12, biotin and folic acid – and C. The fat-soluble vitamins are A, D, E and K.

B1 (thiamin) works with the nervous system and helps the body use carbohydrates for energy. When deficiency occurs, it can cause impaired growth, muscle weakness, mental confusion and more.

B2 (riboflavin) helps the body process protein, carbohydrates and fats. It works to support good vision, healthy skin and the production of red blood cells. Deficiency can cause fatigue, slowed growth, swollen/sore throat and more.

B3 (niacin) assists the body in processing proteins and fats. It also helps the skin, digestive tract and nervous system to remain healthy. Deficiency can result in diarrhea, weakness, skin disorders and pellagra.

Excesses can cause stomach upset, skin flushing and itching, and rash.

The most common cause of too much niacin is from supplemental niacin taken to reduce cholesterol levels; therefore, it should be introduced gradually to prevent unwanted side effects.

B5 (pantothenic acid) helps the body process nutrients and synthesizes hormones and cholesterol. Deficiency is uncommon.

B6 (pyridoxine) aids in the formation of red blood cells and maintains brain function. Deficiency can cause kidney stones, anaemia and nausea. Excess can cause leg pain and more.

B12 (cyanocobalamin) maintains red blood cells, is important for metabolism and the maintenance of the central nervous system, and helps to make DNA.

Deficiency can result in pernicious anaemia and tingling of the fingers and toes.

Biotin helps metabolize fats and carbohydrates. Deficiency is rare. Folic acid/folate prevents birth defects and makes DNA and new red blood cells.

Deficiency can cause anaemia, diarrhoea and other symptoms.

C (ascorbic acid) is an antioxidant necessary for the growth and repair of tissues. It helps repair bones, teeth and cartilage. Excesses can cause kidney stones, upset stomach and an increase in iron absorption.

A (retinol) is necessary for good vision, bone and tooth development and several other functions. Excesses can result in nausea, headache, blurred vision, vomiting and an increased risk of developing osteoporosis.

D (calciferol) helps teeth and bones stay healthy. Deficiency can result in osteoporosis, fractures and rickets (in children). Excesses can cause diarrhoea, constipation, weakness and other problems.

E (tocopherol) acts as an antioxidant that helps the body utilise vitamin K and works to form red blood cells. Deficiency is rare because E is stored naturally in the body for extended periods of time. Excesses include possible haemorrhage and impairment of blood clotting.

K helps with the formation of bone and aids blood clotting. Low levels can lead to excessive bleeding. Excesses can cause liver damage.

People who maintain a well-balanced, healthful diet should not experience deficiency or excesses of vitamins unless there is an underlying condition that alters metabolism.

Problems caused by excess consumption come into play primarily when supplements are used inappropriately or unnecessarily. Deficiency is most common in people who don't eat properly, take medications that reduce a vitamin's efficiency, or are vegetarian or vegan.

To provide more extensive information, I am sending you a copy of my Health Report 'Vitamins & Minerals'.

Other readers who would like a copy should send a self-addressed stamped number ten envelope and a $2 cheque or money order to Newsletter, PO Box 167, Wickliffe, Ohio 44092-0167. Be sure to mention the title or print an order form off my website at www.AskDrGottMD.com.

Dr. Peter H. Gott is a retired physician and the author of several books, including 'Live Longer, Live Better', 'Dr. Gott's No Flour, No Sugar Diet' and 'Dr. Gott's No Flour, No Sugar Cookbook'.