North Americans almost never suffer from vitamin deficiencies, except for vitamin D, yet more than 50 percent of the population spends more than $30 billion each year for vitamin pills and other nutritional supplements that they do not need. Forty-five percent of those who take vitamin pills believe that they will improve their health, but we have no good evidence that they do (JAMA Internal Medicine, Feb. 4, 2013).
The general consensus of the scientific community is that most people who take vitamin pills receive no benefit from them but are not harmed except for the money they have wasted. Many people say that they take vitamin pills because they may not be eating the right foods, but a lousy diet with vitamin pills is still a lousy diet.
How Do Vitamins Affect Your Body?
All of the vitamins necessary for human life and health come from foods, with the exception of vitamin D, which comes primarily from sunlight. Most vitamins, particularly the B vitamins, are parts of enzymes that start chemical reactions. Chemical reactions break down food so that it can be absorbed into you bloodstream, start the process that turns food into the fuel that your body uses for its various functions, and build and repair all the tissues in your body. All of these chemical reactions are started by enzymes made by your body and the bacteria that live in your body.
For example, for chemical A to go to chemical B and release energy for your cells to use, you need a first enzyme to start that chemical reaction. Then you need a second enzyme to break down chemical B to form chemical C and release more energy. If you have the first enzyme, you make lots of chemical B. If you lack the second enzyme that breaks down chemical B, chemical B could accumulate in large amounts in your body and may be toxic, which could cause disease and harm you.
How the B Vitamins Work
Scientists do not know all of the chemical reactions started by vitamins, but they have worked out how some of the B vitamins help to make all of the proteins in your body. All human protein is made up of 21 building blocks called amino acids. Eight amino acids cannot be made by the human body, so they are called essential amino acids. The other 13 can be made from the essential amino acids, so you don’t need to get them from your food; these are called the non-essential amino acids.
For example, you use enzymes from the B vitamins to make the not-essential amino acid cysteine from the essential amino acid methionine. However, methionine must go through several chemical reactions that make homocysteine before it makes cysteine. Thus Methionine > Homocysteine > Cysteine.
However, homocysteine is associated with increased risk for heart attacks, so if it accumulates in the body it can be harmful. Vitamin B6 (pyridoxine) converts homocysteine to methionine and vitamin B9 (folic acid) and/or B12 (cobalamin) that convert homocysteine to cysteine. Vitamin B3 (niacin) converts cysteine back into homocysteine. The B vitamins depend on all of the other B vitamins and more to avoid the buildup of toxic chemicals in your body.
Since nobody really knows all the chemical reactions that go on in your body, I recommend that you eat what most scientists feel is a healthful diet and not depend on pills that have more questions than answers. I recommend that you:
- avoid being overweight
- eat lots of fruits, vegetables and seeds (nuts, beans whole grains)
- restrict sugar-added foods and drinks, red meat, processed meats and fried foods
- avoid all forms of tobacco
- restrict or avoid alcohol
- avoid recreational drugs and unnecessary prescription drugs
Gabe Mirkin, M.D., is a sports medicine doctor and fitness guru. A practicing physician for more than 50 years and a radio talk show host for 25 years, Dr. Mirkin has run more than 40 marathons and is now a serious tandem bike rider with his wife, Diana. His website is http://drmirkin.com/. Click to read Gabe’s full bio.