Vitamins in the right amount are needed for a variety of biologic processes, among them growth, digestion, mental alertness and resistance to infection. They also enable your body to use carbohydrates, fats and proteins, and they act as catalysts — initiating or speeding up chemical reactions. Remember, however, that even though vitamins are involved in converting food into energy, they have no calories, and taking them will not boost your energy levels.
Vitamins can be either fat-soluble or water-soluble. Vitamin C, biotin and the seven B vitamins — thiamin (B-1), riboflavin (B-2), niacin (B-3), pantothenic acid (B-5), pyridoxine (B-6), folic acid (B-9) and cobalamin (B-12) — are water-soluble vitamins and are not stored in your body in any appreciable amounts. Surplus water-soluble vitamins are washed out in your urine. Choline is a nutrient with significant functions within the body and some consider it a water-soluble vitamin, but it's not technically classified as a vitamin.
Fat-soluble vitamins — vitamins A, D, E and K — are stored in your fat. Excess fat-soluble vitamins can accumulate in your body and become toxic. You're especially sensitive to excess amounts of vitamins A and D. Because vitamins E and K affect blood clotting, talk with your doctor before taking a supplement that contains either of these vitamins if you're taking a blood thinner.
Your body needs minerals to help regulate cell function and to serve as building blocks for your cells and organs. Major minerals include calcium, phosphorus, magnesium, sodium, potassium, sulfur and chloride. Your body needs smaller amounts of chromium, copper, fluoride, iodine, iron, manganese, molybdenum, selenium and zinc.
(Source: Mayo Clinic website – www.mayoclinic.com)