Diabetics Benefit From Supplements

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March 3, 2003 -- Although the use of daily multivitamin supplements among well-fed people has long been debated, with studies providing mixed results, new research indicates that the over-the-counter pills can help people with diabetes dramatically reduce their risk of cold, flu, and other infections.

This study is among the first to look specifically at how vitamin supplements -- regularly consumed by about 40% of Americans -- impact immune function in those with type 2 diabetes, who are more susceptible to various viral and bacterial infections. Along with 51 diabetic patients, researchers also studied self-reported rates of infections in 79 people without diabetes. Everyone in the study was at least 45 years old.

Among all participants, 43% of those taking daily supplements reported getting sick during the study, compared with 73% of those getting a placebo. In those with diabetes, 93% taking a placebo got sick, compared with only 17% on the active supplements. However, in those without diabetes, there was no measurable difference between supplement- and placebo-takers.

"The take-home message of our finding suggests that vitamins may be helpful and they may not be, depending on who you are," says researcher Thomas A. Barringer, MD, research director at Carolinas Medical Center in Charlotte. "If you have type 2 diabetes, there may be something in the vitamins that seems to replete nutritional deficiencies caused by the disease."

Researchers have long known that persons with type 1 and type 2 diabetes are more prone to various infections because of impaired immunity.

"There are probably several factors," says Eugene Barrett, MD, PhD, president-elect of the American Diabetes Association. "High blood sugar seems to impede the way (infection-fighting) white blood cells work so they can't kill bacteria as well as when blood sugar is at normal levels. Studies find that controlling blood sugar makes a big difference in controlling infection."

Other research suggests that frequent urination causes diabetics to lose nutrients such as zinc and selenium -- key in keeping immunity strong. The supplements used in Barringer's study were higher-than-average in these nutrients, but still close to the formulas in most commercially available products.

Barrett tells WebMD that this study, published in the March 4 issue of Annals of Internal Medicine, is a great first step in learning more about how vitamins may help people with diabetes reduce their risk of nagging infections such as colds, flu, and urinary tract and stomach infections. "But it's a small study, so it's too early to recommend that people with diabetes take daily vitamin supplements as a matter of policy. More study is needed."

"The diabetic patients we recruited for our study tended to be poorer, less educated, more obese, and generally had a worse diet than those who didn't have diabetes," Barringer tells WebMD. "At least one-third of them didn't meet at least 33% of RDA [recommended daily allowance] levels for certain key nutrients." These nutrients included but were not limited to vitamins A, C, and E. All participants kept detailed food diaries during the study, but the diabetics were recruited from an inner-city diabetes clinic, while those without the disease came from a middle-class health clinic and generally ate more nutritiously and were less likely to be obese.

The fact that these healthier, non-diabetic patients didn't benefit from supplements backs several previous studies that find vitamin supplements provide no real benefit for the average well-nourished person -- including one of the larger studies published last August by Dutch researchers.

But other studies have found daily supplements can boost immunity even among those who eat healthfully -- especially the elderly. Many of these findings have been noted by Ranjit K. Chandra, MD, PhD, FRCPC, who has personally conducted some 50 trials examining the role of supplements on immune function and is arguably the world's most prolific researcher in this area.

"Nutritional deficiencies in seniors are common, even in the U.S. and Canada," he tells WebMD. "Supplement formulas used in the Dutch study and some others had only 25%-50% of RDA values of some trace minerals." In addition to zinc and selenium, he says other key nutrients lacking in other studies include vitamins A, B6, B12, C, E, and folate.

"The bottom line is that if seniors regularly take a multivitamin-mineral supplement documented to contain optimum amounts of these nutrients, one might expect a reduction in common respiratory infections -- and such a preparation would also benefit those with no obvious nutritional deficiency."

So should you take vitamins?

"I have, but I go hot and cold -- like many Americans," says Keith West, DrPH, of the Johns Hopkins Center for Human Nutrition, who studies use of these nutrients in malnourished persons. "But I've been away from it in recent years because I have failed to find clear evidence of any public health benefit from supplements in those who eat a good diet. My advice: Get your nutrients by eating more vegetables, which has not failed to be associated with many health benefits, including strong immune function."

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SOURCES: Annals of Internal Medicine, Mar. 4, 2003. Journal of the American Medical Association, Aug. 14, 2002. Thomas A. Barringer, MD, research director, family medicine, Carolinas Medical Center, Charlotte; clinical associate professor of medicine, University of North Carolina, Chapel Hill. Eugene Barrett, MD, PhD, president-elect, American Diabetes Association; professor of internal medicine and pediatrics, director of the Diabetes Center, University of Virginia School of Medicine, Charlottesville. Ranjit K. Chandra, MD, PhD, FRCPC, director, World Health Organization Centre for Nutritional Immunology; university research professor, Memorial University of Newfoundland, St. John's, Canada; Carnegie Visiting Professor, Johns Hopkins University, Baltimore.

Keith West, DrPH, professor of international health, Center for Human Nutrition at Johns Hopkins Bloomberg School of Public Health.
© 2003 WebMD Inc. All rights reserved.

Sid Kirchheimer, Monday, March 03, 2003, Vitamins Reduce Rates of Colds and Other Infections for Those With Diabetes, Reviewed By Brunilda Nazario, MD, WebMD Medical News, http://content.health.msn.com/content/article/61/68083.htm