Getting old is inevitable. But getting sick as we get old is not. 

That was the message of the first annual Healthy Aging Symposium, hosted by the Harvard T.H. Chan School of Public Health and supported by the Danone Institute of North America. 

“Not only do we know now that we can slow aging in the lab, but thanks to advances in molecular biology starting about 40 years ago, biologists and geroscientists have actually been able to lift up the hood and look inside the engine and see why it is, how it is that we’re able to slow aging,” said keynote speaker Daniel Promislow, senior scientist and scientific adviser at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University. 

Hundreds of experts, students, and postdocs in biology, social science, nutrition, environmental health, epidemiology, policy, and other disciplines convened to share expertise in the rapidly growing science of healthy aging. Presentation topics included environmental health and immune resilience, the biomarkers of aging, and intermittent fasting. 

The symposium was the brainchild of William Mair, a professor of molecular metabolism at the Chan School and the director of its Healthy Aging Initiative. 

“We launched the Healthy Aging Initiative to try to build toward a greater vision that changes how we think about and fund work on aging,” Mair said. The symposium “is an early example of this, giving us a rare opportunity to highlight the breadth of research at the Chan School in one place. My goal is that our initiative and events like this catalyze a unified focus on healthy aging across the wider University.”

Although Mair studies the molecular and cellular mechanisms of aging, he takes a decidedly public-health approach to the problem. In the 20th century alone, Mair said, average U.S. life expectancy rose by 30 years, largely thanks to public health interventions such as clean water, sanitation, and vaccines. But as more people survive into old age, more develop the diseases of longevity, such as metabolic and neurodegenerative disorders. 

As Chan School Dean of the Faculty Andrea Baccarelli, put it, “The average American can expect to live the last 12 years of their lives with multiple comorbidities, often with a fair burden not only to the health systems in society but to families, to caregivers, and to everyone around them.” 

Living longer is a good problem to have, Mair said, but a problem nonetheless. 

“How do we think about the next century of public health, and try to make it so we can all age healthier, not just live a long time?” 

Frank Hu, Fredrick J. Stare Professor of Nutrition and Epidemiology at the Chan School, sees hope in what he calls “Nutrition 3.0.” Nutrition 1.0 focused on preventing nutrient deficiencies; Nutrition 2.0 was about preventing chronic disease. The next frontier, he said, is precision nutrition and healthy longevity.

Hu draws on data from the Nurses’ Health Study, a long-running cohort study of some 300,000 healthcare workers. The study just celebrated its 50th anniversary this year, so its original participants are now in their 70s and older. It’s a massive body of data on dietary habits and the biomarkers of aging. 

“We’ve made tremendous progress in improving nutrition and epidemiology methods, so now we have much better dietary assessment tools, which have been rigorously vetted, which can actually reduce measurement error,” Hu said. 

In other words, broadly speaking, we know what works in nutrition — though, Hu added, getting people to follow through on it remains a challenge. 

Less clear, at least right now, is the efficacy of moonshot ideas for extending lifespan through targeted therapies. Promislow runs the Dog Aging Project at Tufts, a cohort study of 55,000 canine companions. Why dogs? They share our living environments, have diverse genes, and develop many of the same chronic diseases we do, but they age much faster. And, Promislow added, people get more invested in research about dogs than about fruit flies. “When I give a talk about fruit fries to a general public audience, I can guarantee that nobody ever comes up to me afterward and says, ‘Oh my goodness, I love fruit flies,’” he joked. 

Promislow’s team has identified metabolites that predict mortality in dogs — metabolites that humans share, in similar hazard ratios. The team is now enrolling dogs in a clinical trial testing whether the drug rapamycin can delay the onset of disease. Given how fast dogs age, the study could show results in as little as five years. “There’s huge potential for the biological community to learn a lot from dogs,” he said.

In a day that drew connections across disciplines and research methods, Mair credited the Chan School’s capacity to bring people together. 

“The Chan School of Public Health is unique as a place to tackle healthy aging as we have experts under one roof that tackle the problem from completely different angles, from lab-based discovery science, nutrition, and environmental exposure to epidemiology, population science, social science, policy, and implementation. Healthy aging for all will require everyone to come together to effect real change,” he said.