Following a Combination of Healthy Lifestyle Factors May Sharply Reduce Risk of Premature Death

For immediate release: September 16, 2008

Boston, MA -- A number of studies have shown associations between individual lifestyle factors, such as smoking and diet, and risk of chronic diseases, including cardiovascular diseases, type 2 diabetes and various cancers. Few studies, however, have looked at the bottom line -- how a combination of lifestyle factors might influence mortality.

A new, large-scale study from researchers at the Harvard School of Public Health (HSPH) shows that women who followed a combination of healthy lifestyle factors -- not smoking, maintaining a healthy weight, regular physical activity and a healthy diet -- had a dramatically lower risk of dying from all causes during the two-and-a-half decades of the study. Furthermore, their risk reduction surpassed that from following any single healthy factor alone. It is the largest and longest-running study to directly estimate the impact of a combination of lifestyle factors on mortality. The study appears in advance online on Wednesday, September 17, 2008 in The British Medical Journal.

"A healthy diet and lifestyle has a profound influence on risk of premature death due to chronic diseases. The results of the study reinforce the need to strengthen public health efforts around quitting smoking, maintaining a healthy weight and diet and performing regular physical activity," said Rob van Dam, assistant professor in the Department of Nutrition at HSPH and in the Channing Laboratory, Brigham and Women's Hospital and Harvard Medical School, who led the study.

The research team analyzed data from 77,782 women participating in the Brigham and Women's Hospital-based Nurses' Health Study. The researchers analyzed the participants' responses to questionnaires about lifestyle and health conditions over a 24-year period, beginning in 1980. During the follow-up, 8,882 deaths were recorded, including 1,790 from cardiovascular disease and 4,527 from cancer.

Van Dam and his colleagues estimated that 55% of deaths from all causes, 44% of cancer mortality and 72% of cardiovascular mortality during follow-up could have been avoided if participants had never smoked, engaged in regular physical activity, avoided becoming overweight and ate a healthy diet. For individual factors, the authors found that 28% of deaths could be attributed to smoking, 14% to being overweight, 17% to lack of physical activity, 13% to an unhealthy diet and 7% to not having light-to-moderate alcohol consumption (one drink a day or less for women). For nonsmoking women, 22% of deaths could be attributable to being overweight.

Light-to-moderate alcohol consumption was associated with lower cardiovascular mortality; higher consumption (two or more drinks per day) with an increased risk of cancer mortality.

"Our findings suggest that the combination of lifestyle factors has a substantially larger impact on survival than any single factor. Clearly, avoiding smoking is of major importance for health, but regular physical activity, a healthy diet and weight management can result in large additional health benefits. Even modest lifestyle changes such as 30 minutes of moderate intensity physical activity (e.g., brisk walking) per day significantly reduced risk of premature death," said van Dam.

"Because prevalence of smoking has declined but prevalence of obesity is increasing rapidly, the impact of obesity on chronic diseases and mortality will become even more pronounced in the future," added Frank Hu, professor of nutrition and epidemiology at HSPH, and senior author of the study.

The research was supported by the National Institutes of Health.

"Combined Impact of Lifestyle Factors on Mortality: Prospective Cohort Study in US Women," Rob M van Dam, Tricia Li, Donna Spiegelman, Oscar H Franco, Frank B Hu, British Medical Journal, online September 17, 2008.

For more information:

Todd Datz
617-432-3952
tdatz@hsph.harvard.edu

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Harvard School of Public Health ( http://www.hsph.harvard.edu ) is dedicated to advancing the public's health through learning, discovery, and communication. More than 400 faculty members are engaged in teaching and training the 1,000-plus student body in a broad spectrum of disciplines crucial to the health and well being of individuals and populations around the world. Programs and projects range from the molecular biology of AIDS vaccines to the epidemiology of cancer; from risk analysis to violence prevention; from maternal and children's health to quality of care measurement; from health care management to international health and human rights. For more information on the school visit: http://www.hsph.harvard.edu