Neither the American Heart Association nor the American College of Cardiology recommends vitamin or mineral pills to prevent heart attacks, and the US Preventive Services Task Force and the National Institutes of Health recommend against the routine use of vitamin or mineral pills to prevent chronic diseases. 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.
A new analysis of 28 different studies that followed more than 83,000 healthy people over age 40 for up to 18 years found that pills containing B vitamins, beta carotene, vitamins C, vitamin D, vitamin E, zinc, copper or selenium (alone or in combinations) do not prevent or treat dementia and loss of brain function with aging (Cochrane Database of Systematic Reviews, December 17, 2018). Other studies that have failed to show benefits from vitamin or mineral pills include:
• A review of 179 different studies on vitamins A, B1 (thiamin), B2 (riboflavin), B3 (niacin), B6 (pyridoxine), B9 (folic acid), C, D, E, beta-carotene, and the minerals calcium, iron, zinc, magnesium, and selenium, showed that there was no reduction in incidence of heart disease, stroke or premature death, compared to people who did not take vitamin pills (Journal of the American College of Cardiology, June 5, 2018;71(22):2570-2584).
• A review of 18 studies, following more than two million men and women for an average of 12 years, showed that vitamin and mineral pills do not reduce risk for dying from heart disease or strokes, or even for getting a stroke, regardless of age (Circulation: Cardiovascular Quality and Outcomes, July 2018;11(7)).
• A study followed almost 30,000 people in China, aged 40-69, 25 years after they had taken vitamin and mineral pills for five years. They had no reduction in death or cancer rates from vitamin or mineral pills (J National Cancer Institute, July 11, 2018).
• Additional studies are included in the References section below.
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 your bloodstream, start the processes that turn food into the fuel that your body uses for its various functions, and build and repair all of the tissues in your body. All of these chemical reactions are started by enzymes made by your body and by 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 non-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 may be harmful. Vitamin B6 (pyridoxine) converts homocysteine to methionine and vitamin B9 (folic acid), and/or B12 (cobalamin) converts 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.
Who May Benefit from Specific Vitamin or Mineral Pills
Many years ago, scurvy was common in people who did not eat fruit as a source of vitamin C, and beriberi was common in people who lacked thiamine because they did not eat whole grains. Today diets are more varied and many processed foods are fortified, so these deficiency diseases are rarely seen, and then usually only in illness or severe deprivation. North Americans die far more often from diseases caused by excess food than from deficiencies.
Specific vitamins or minerals may be recommended for:
• people with vitamin deficiencies from inability to absorb certain vitamins such as B12
• people with conditions that make it difficult to absorb and retain food nutrients
• people with diseases that cause body or muscle wasting
• some people with heart disease
• pregnant women, who are given prenatal vitamins
• vegans who eat no animal products at all and need a source of vitamin B12
• some older people who do not eat properly or people with restricted eating patterns
• vitamin D for people who do not get adequate sunlight
• some people whose bodies cannot metabolize B12 (homotranscobalamine)
• possibly people with macular degeneration
• people with stomach problems who must take proton pump inhibitors
• possibly some people on metformin to treat diabetes
There is no scientific evidence that vitamin or mineral pills prevent dementia, heart attacks or chronic diseases in the general population. Micronutrients in food are typically better absorbed by the body than those from pills, so I do not recommend taking vitamin pills, mineral pills or other supplements unless you and your doctor have identified a special need such as those listed above. A lousy diet with supplements is still a lousy diet. Since nobody knows all the chemical reactions that go on in your body, I recommend that you follow what most scientists consider to be healthful lifestyle habits (including diet), and not depend on pills that have more questions than answers.
• eat lots of vegetables, fruits, and seeds (nuts, beans, whole grains)
• restrict sugar-added foods and drinks, red meat, processed meats and fried foods
• avoid overweight
• avoid all forms of tobacco
• restrict or avoid alcohol
• avoid recreational drugs and unnecessary prescription drugs