Boston, MA -- Controlling blood pressure, serum cholesterol, and blood glucose may substantially reduce the risk of heart disease and stroke associated with being overweight or obese, according to a study from a worldwide research consortium led by a team from Harvard School of Public Health (HSPH), Imperial College London, and the University of Sydney. Among the three factors, high blood pressure was found to pose the biggest risk for heart disease, and an even bigger risk for stroke, among overweight or obese participants.
"Our results show that the harmful effects of overweight and obesity on heart disease and stroke partly occur by increasing blood pressure, serum cholesterol and blood glucose. Therefore, if we control these risk factors, for example through better diagnosis and treatment of hypertension, we can prevent some of the harmful effects of overweight and obesity," said senior author Goodarz Danaei, HSPH assistant professor of global health.
The study appears online November 22, 2013 in The Lancet.
Worldwide, obesity has nearly doubled since 1980, according to a previous study by the research team, and more than 1.4 billion adults aged 20 and older are overweight or obese. Health consequences of overweight and obesity include heart disease and stroke--the leading causes of death worldwide--diabetes, and several types of cancer. The researchers had also previously estimated that 3.4 million annual deaths are due to overweight and obesity.
While previous research had indicated that blood pressure, cholesterol, and blood sugar all increase the risk of heart attack and stroke in people who are overweight or obese, this new study--a pooled analysis of 97 prospective studies from around the world that enrolled 1.8 million participants--provides a comprehensive and definitive look by considering blood pressure, cholesterol, and glucose separately and together and in different parts of the world.
The researchers looked at these three factors because they are likely pathways through which obesity increases the risk of heart disease and stroke and because they are of interest to physicians and public health agencies. They found that high blood pressure, serum cholesterol, and blood glucose explain up to half of the increased risk of heart disease and three quarters of the increased risk of stroke among overweight or obese participants. High blood pressure poses the biggest risk of the three metabolic factors examined. It accounted for 31% of the increased risk of heart disease and 65% of the increased risk of stroke among overweight or obese individuals.
Majid Ezzati, a co-author and professor of global environmental health, Imperial College London, said: "Controlling hypertension, cholesterol, and diabetes will be an essential but partial and temporary response to the obesity epidemic. As we use these effective tools, we need to find creative approaches that can curb and reverse the global obesity epidemic."
Other HSPH authors included Yuan Lu, doctoral candidate in the Department of Global Health and Population, Eric Rimm, associate professor in the Departments of Epidemiology and Nutrition, and Kaveh Hajifathalian, postdoctoral research fellow, Department of Global Health and Population.
Funding for the study came from the UK Medical Research Council; the National Institute for Health Research Comprehensive Biomedical Research Centre at Imperial College Healthcare NHS Trust; NIH grant RO1 DK090435; the Lown Scholars in Residence Program on cardiovascular disease (CVD) prevention; and from a Harvard Global Health Institute Doctoral Research Grant.
"Metabolic mediators of the effect of body-mass index, overweight, and obesity on coronary heart disease and stroke: a pooled analysis of 97 prospective cohorts with 1.8 million participants," Yuan Lu, Kaveh Hajifathalian, Majid Ezzati, Mark Woodward, Eric B. Rimm, and Goodarz Danaei, The Lancet, online November 22, 2013
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About Harvard School of Public Health
Harvard School of Public Health brings together dedicated experts from many disciplines to educate new generations of global health leaders and produce powerful ideas that improve the lives and health of people everywhere. As a community of leading scientists, educators, and students, we work together to take innovative ideas from the laboratory and the classroom to people's lives--not only making scientific breakthroughs, but also working to change individual behaviors, public policies, and health care practices. Each year, more than 400 faculty members at HSPH teach 1,000-plus full-time students from around the world and train thousands more through online and executive education courses. Founded in 1913 as the Harvard-MIT School of Health Officers, the School is recognized as America's first professional training program in public health.
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About Imperial College London
Consistently rated amongst the world's best universities, Imperial College London is a science-based institution with a reputation for excellence in teaching and research that attracts 14,000 students and 6,000 staff of the highest international quality. Innovative research at the College explores the interface between science, medicine, engineering and business, delivering practical solutions that improve quality of life and the environment - underpinned by a dynamic enterprise culture.
Since its foundation in 1907, Imperial's contributions to society have included the discovery of penicillin, the development of holography and the foundations of fibre optics. This commitment to the application of research for the benefit of all continues today, with current focuses including interdisciplinary collaborations to improve global health, tackle climate change, develop sustainable sources of energy and address security challenges.
In 2007, Imperial College London and Imperial College Healthcare NHS Trust formed the UK's first Academic Health Science Centre. This unique partnership aims to improve the quality of life of patients and populations by taking new discoveries and translating them into new therapies as quickly as possible.