By Lindsay Key
It’s a muggy morning in late August in Durham, N.C.—the temperature has already hit 85 degrees by 9 a.m.—and Jeff Letourneau is headed into the woods. The PhD student in Duke’s Department of Molecular Genetics and Microbiology is out looking for pawpaws—the green, mango-sized fruit with a creamy yellow center. He uses them to make a variety of foods and beverages for his family, including smoothies, custard, and even beer. Often, he just slices them open and eats them plain after being chilled in the refrigerator.
“They have a mango-banana taste,” he says. “They’re delicious.” The largest native fruit in North America, pawpaws can be found growing on trees in wooded areas in central North Carolina during their peak season of late August and early September. Like many wild foods, says Letourneau, most people don’t notice them or realize their nutritional value.
His interest in wild food foraging, which intensified during the pandemic last year, goes far beyond the convenience of free local food. As a budding scientist in the lab of Lawrence David, PhD, associate professor of molecular genetics and microbiology, Letourneau studies the effects of a high-fiber diet on human health.
Dietary fiber is the portion of plant-derived food (fruits, vegetables, whole grain products, beans, nuts and seeds) that cannot be completely broken down by digestive enzymes. In humans, a high fiber diet helps promote healthy gastrointestinal function, assists in weight management, and reduces risk of cardiovascular disease and Type 2 diabetes, according to the United States Department of Agriculture (USDA). However, according to a 2016 study, only about 5% of the U.S. population eats the recommended amount of fiber each day, which is a minimum of 14 grams per 1,000 calories.
“The biggest thing you learn in this field is that none of us are eating anywhere near enough fiber,” said Letourneau. He and David, who is a member of the Duke Microbiome Center, have set out to determine how fiber intake impacts the gut microbiome—the trillions of bacteria, fungi, and other microbes that live in the digestive system. They are using a systems-based approach to their research, thinking of the gut microbiome as its own ecosystem and the fiber particle that enters it as a disturbance.
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