Dr. Simin Liu didn’t just breeze into Brown’s epidemiology and medicine departments for spring semester. He arrived in a whirlwind. In the preceding months he was in Washington, D.C., for a global health think tank convened by the National Institutes of Health. Before that, he was in the Middle East to deliver a lecture for the World Health Organization on the challenges of assessing and controlling chronic diseases such as obesity and diabetes. Liu also gave a keynote about recent advances in studying gene-nutrition interactions for complex diseases at the second international symposium on Nutrition and Health in China.
For two decades Liu has studied how factors ranging from genes to diet and lifestyle to the environment intermingle as causes and mediators of complex diseases.
“Obesity and diabetes really are the epidemics of our time,” he said. “Their significant impact on societies everywhere demand that biomedical scientists and policymakers alike be well-versed in issues ranging from molecular genetics to public health sciences concerning these devastating phenotypes.”
It’s important to say this is happening, but it’s even more important to figure out how it happens and how it can be helped. Liu, a physician-scientist, embodies the broad array of skills required, imbues his students with them, and collaborates broadly in an effort to tackle the world’s biggest health problem.
“What better discipline than epidemiology to integrate all the major advancements in the field from basic molecular science to population science and improve our understanding of these conditions at both individual — and population — levels?” Liu said.
Publishing and pedagogy
Liu’s public health career started at the Centers for Disease Control and Prevention where he conducted outbreak investigations and participated in developing national surveillance systems for chronic diseases. He then joined the faculty of the Department of Medicine at the Brigham and Women’s Hospital and Harvard School of Public Health, where he also earned a doctorate in epidemiology and nutrition in 1998. In 2005, he moved to the University of California–Los Angeles where he established the Center for Metabolic Disease Prevention and the Burroughs-Wellcome Fund Inter-School Training Program in Metabolic Diseases, a cross-disciplinary research and training program for developing scientists capable of integrating laboratory-based biological sciences into population-based disciplines.
He has authored or co-authored more than 200 papers, disseminating influential results from virtually every study methodology there is: systematic reviews, statistical analyses of published data, clinical trials, and direct observations from lab analyses of genetic markers and blood serum levels of hormones and other biochemicals.
In 2000, for example, he led a study in the Journal of the American Medical Association (JAMA) showing that whole grains consumption was associated with a reduced risk of stroke in women. That same year he also led a study in the American Journal of Clinical Nutrition (AJCN) – cited nearly 900 times since – that showed an elevated coronary heart disease risk among women who ate a diet high in “glycemic load” from processed carbohydrates.
Establishing such specific, quantifiable risk factors can help doctors assess risk in people while they are still ostensibly healthy.
In more recent years, Liu has dug deep into the underlying molecular biology that not only helps further explain differences in risk, but also suggests potential remedies.
In a series of papers between 2006 and 2010, his team discovered a gene variant that affects how magnesium regulates glucose levels in the body. Women with low magnesium in their diets appeared to be a greater risk for type 2 diabetes. This led to a small clinical trial, published in AJCN in 2010, in which Liu and colleagues found that among overweight individuals, four weeks of magnesium supplements reduced insulin levels and other troublesome metabolic biomarkers compared to a placebo and changed how the related genes were expressed.
At the same time, Liu and his colleagues led investigations of the role that sex hormones such as testosterone apparently play in differences in the risk of type 2 diabetes and related cardiovascular disease in men and women. The first was a 2006 paper in JAMA, followed up with several more including a paper in the New England Journal of Medicine.
“I think we fairly conclusively established the sex-hormone binding globulin as a causal factor for type 2 diabetes,” he said.
Earlier this year, his team authored a paper in The Journal of Nutrition including frequent collaborator Dr. Charles Eaton, professor of family medicine and epidemiology at Brown, linking higher intake of certain short-chain fatty acids with shorter telomeres. Telomeres are DNA sequences on the ends of chromosomes whose length serves as a sign of aging at the cellular level.
New collaborations at Brown
Liu came to Brown in part to become reunited with family and friends in New England. He met his wife, a native New Englander with deep roots in the region, while studying at Harvard and now their young kids live much closer to grandparents and cousins. But Brown’s Alpert Medical School and Brown’s new School of Public Health offer rich veins of collaborators. He’s already begun working with and applying for new grants with colleagues including Joe Braun, Yen-Tsung Huang, Xi Luo, Haiyan Xu, Steve McGarvey, and David Savitz.
“The exceptionally talented and accomplished researchers who are already here are very attractive to me,” he said.
With Braun, for example, he hopes to examine the effect that endocrine disrupting chemicals might be having on cardiometabolic disease, for instance because they affect sex hormones like the ones that he’s shown to be predictive of the disease.
There will be many collaborations.
“The next step is to bring good people together in further expanding our collective experience in developing new research and education programs,” he said. “People are the most important asset.”