BOSTON—Vitamins, minerals, and herbal supplements can help complement a healthy diet and lifestyle, but consumers shouldn’t count on them to boost their immune response, says the new edition of a Harvard Medical School report, The Truth About Your Immune System: What you need to know.

   The immune system defends the body against invading microbes such as bacteria and viruses. Many supplement manufacturers claim their products “support” immunity. But so far, there is not enough scientific evidence to back up the claims. The reason, according Michael N. Starnbach, Ph.D., the Harvard Medical School expert who edited The Truth About Your Immune System, is that science has not yet determined what level of immune system cells will best help the body resist disease. While some proponents of vitamins and supplements claim that boosting the number of immune cells improves immunity, that link has yet to be established. The variety of immune cells is vast, and their interactions remain largely unknown.

   The Truth About Your Immune System explains what scientists do know about human immunity and also describes areas under investigation, including the development of new vaccines and the influence of lifestyle on immunity. So far, the report says, the lifestyle factors that appear to help keep the immune system in shape are the same ones that promote overall health, such as these:

avoiding tobacco
eating a diet high in fruits, vegetables, and whole grains, and low in saturated fat
exercising regularly
maintaining a healthy weight
controlling your blood pressure
drinking only in moderation (if at all)
getting adequate sleep
taking steps to avoid infection, such as washing your hands frequently and preparing foods safely.

   Dr. Starnbach, the editor of the 43-page report, is a professor of microbiology and molecular genetics at Harvard Medical School. www.health.harvard.edu/E

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