The most honest answer is that unless you have an obvious vitamin or mineral deficiency disease, no one really knows. People vary in their ability to absorb and use nutrients.

At particular times you are likely to need specific extra vitamins and minerals from birth to adolescence; when you take birth control pills; when you are pregnant and nursing; and after menopause, when you slowly become less efficient at absorbing nutrients.

In the US today one fourth of what we eat is often made up of foods which provide calories and not much else, like a soda and sugary snacks and alcohol. These empty calories foods combined with foods stripped of nutrients through processing or for other reasons, may mean we are not getting enough of all the nutrients we need.

Government surveys have shown that calcium, and iron are two minerals and B6 is one vitamin often lacking in our diet. Folic acid, a B vitamin important during pregnancy, is also often lacking. Your specific needs are based on combination of your unique biochemical inheritance, which currently is difficult to assess; the environmental stresses in your life; and how well you eat.

You may be able to find out if you have a deficiency by experimenting with dietary changes or with nutritional supplements. We need to pay attention to and trust our bodies to help us find out what our special needs are.

There are particular nutritional stresses that you may be putting your self under. If you smoke you need about 120 milligrams of Vitamin C a day, about twice the usual amount. You can get this amount from two orange or fourteen ounces of baked potatoes. Many drugs effect vitamin and mineral use. Asprin affects folic acid absorption and depletes tissues of Vitamin C.

Even though supplements are fast and easy to take and you know exactly what you are getting., they cannot substitute for fresh whole food because we don't yet know all of the nutrients necessary for our health. You cannot get some things easily from pills, like fiber. Also many nutrients are useless or are less effective if taken by them.