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In recent years, aging research has shifted its focus from lifespan to healthspan to understand the processes that define aging. Dr. Heidi Tissenbaum’s research investigates the fundamental pathways and genes that determine how we age.
In the latest episode of Longevity by Design, our co-hosts, Dr. Gil Blander and Ashley Reaver, are joined by Dr. Heidi Tissenbaum, professor at the University of Massachusetts Medical School. Tune in as Dr. Heidi Tissenbaum distinguishes between lifespan and healthspan, how she uses C. Elegans as a model organism for aging, and how added dietary sugars can interfere with longevity.
Dr. Heidi Tissenbaum joined the Program in Gene Function and Expression at the University of Massachusetts Medical School in 2001. Dr. Heidi Tissenbaum graduated with a Ph.D. in Genetics from Harvard Medical School.
As the daughter of a physician and a nurse, Dr. Heidi Tissenbaum knew she wanted to pursue a career in science. As a graduate student, Dr. Heidi Tissenbaum was interested in the gene DAF-2 that impacts development and lifespan. She then joined Dr. Lenny Guarente’s lab as a postdoc. Later, she pursued a professor position at the University of Massachusetts Medical School. “So when I started, we isolated individual genes that affected lifespan. But over 25 years or so, we moved beyond that and into how we can affect our healthspan.”
Dr. Heidi Tissenbaum's recent research is careful to distinguish between outcomes of lifespan and healthspan. She explains why this distinction is important, "In aging research, people often use lifespan synonymously with aging, but they're not the same. Lifespan is a measurement of the aging process, but the aging process is much more than how long a person lives. So we can look at two people that are the same age, and they look very different. And on the inside, it's probably even more different."
Dr. Heidi Tissenbaum talks about how the field currently targets improving health: "If we divide life into three parts, we have early development, middle age, and death. I think the focus of aging research is to move that middle age. How can we be healthier, live better, and prolong the time before we get age-associated diseases?"
According to Dr. Heidi Tissenbaum, here are ways to quantify healthspan: "I think the longevity field has moved to improve healthspan. And what healthspan means is that if you look at an animal throughout its life, you see markers that make it look younger than it should. In C. elegans, we look for markers of health, such as movement or resistance to stress."
C. elegans is a hermaphrodite roundworm that is about one millimeter long. The human-like physiological changes of C. Elegans make it a valuable model for aging research. "C. Elegans only live for three weeks, and although we want to keep animals alive for a long time, this makes them inexpensive and easy to maintain. So, C. Elegans are a primary system for aging research because of their short, reproducible lifespan."
Dr. Heidi Tissenbaum and her team found specific genes that describe the aging process throughout her career. “The very first gene that we isolated was age-1, shown to affect development. We then identified it as a PI 3-kinase, the catalytic subunit of an enzyme shown to be important in insulin regulation. Then, we cloned another gene in the pathway, daf-2 and then daf-16. And what was beautiful for us was age-1, daf-2, and daf-16 were genetically already in a separate pathway.”
Added sugar sneaks its way into many of the foods we consume. For this reason, Dr. Heidi Tissenbaum wanted to understand how added dietary sugar impacts the gut microbiota and longevity.
"When you go into the grocery store, everything has added sugar. It's just everywhere. It seems like in the '90s, when they got rid of fat in foods, they replaced it with sugar. For example, milk, yogurt, cereal, bread all have added sugar. And excess dietary sugar is associated with outcomes like metabolic diseases. That's why we're interested in researching sugar." Tune in to the episode to hear what Dr. Heidi Tissenbaum’s research reveals about the relationship between dietary sugar and longevity.
When asked about habits she practices daily for health and longevity, Dr. Heidi Tissnbaum replied, "For me, it's always about keeping the mind and body active. So, I challenge my brain every day by doing different things. I also watch my sugar intake; I don't have added sugar."