image: Scientists Claire Berryman and Stephen Hennigar view more
Credit: Eddy Perez/LSU
Scientists Claire Berryman and Stephen Hennigar joined LSU's Pennington Biomedical Research Center to build on three decades as the leading academic provider of nutrition science for the Department of Defense.
As the Louisiana Legislature made a historic investment in LSU and its Pennington Biomedical Research Center, or PBRC, last year, the university is now following the state's lead by adding critical expertise and growing one of PBRC's most successful and sustained research programs: providing the United States military with biomedical solutions to keep American soldiers at optimal health and performance.
Integral to LSU's Scholarship First Agenda, announced last year, the university is now making strategic investments in research to elevate the state and nation and improve the health of all Louisianans. PBRC's work to support the military happens at the intersection of LSU's defense and biomedical priorities, but will ultimately benefit everyone—not just soldiers.
Building on three decades as the go-to provider of nutrition science for the Department of Defense, or DoD, PBRC attracts some of the nation's best rising scientists who are focused on research to keep America's soldiers at the top of their game. This includes the recent recruitment and hiring of Claire Berryman and Stephen Hennigar.
Before joining LSU's Pennington Biomedical, Berryman and Hennigar both worked for several years as post-doctoral researchers for the United States Army Research Institute of Environmental Medicine, or USARIEM—PBRC's primary partner on DoD-funded research—and then as assistant professors at Florida State University. They've been awarded DoD funding of their own and have collaborated on past military projects with established PBRC researcher Jennifer Rood.
While the state invested $1 million in new faculty hires at PBRC in 2022, Berryman brings with her a $2.3 million federal R01 grant. This grant is for a new research project she's beginning for the National Institute of Diabetes and Digestive and Kidney Diseases, part of the National Institutes of Health, to solve a mystery related to metabolism and weight loss. Berryman will examine why it's easier to lose weight and turn carbohydrates and sugars into energy at high altitude, like in Colorado, than around sea level, such as in Louisiana. The results of this study could lead to new treatments and improved care for both diabetes and obesity, which pose enormous health challenges in the state and therefore are at the core of PBRC's research mission.
In addition, Berryman and Hennigar will be collaborating with Rood and another leading PBRC researcher, Tiffany Stewart, on a new $3.6-million federally-funded project to specifically support soldier health and performance.
"We have a lot of experience working with military populations and we're both really excited to join the LSU research family," Berryman said. "The research experience at Pennington Biomedical is unmatched. It's one of the best nutrition programs in the country and other universities can't compete as far as opportunities, resources and support for research."
"We also see a lot of similarities between USARIEM and Pennington Biomedical because the science is meant to be immediately applicable and directly translatable to the populations we serve," Hennigar added.
Most often, Berryman and Hennigar work as a team. Berryman's expertise lies primarily in conducting human intervention trials and using large surveys to understand energy balance and macronutrient (fat, carbohydrate and protein) metabolism, while Hennigar is focused on micronutrient (vitamin and mineral) metabolism in the body. In particular, Hennigar is studying how inflammation and infection, or not consuming enough calories, can prevent a person from absorbing iron—even from iron-rich foods—and lead to declines in iron status over time.
Iron deficiency or its more severe form, iron deficiency anemia, can result in decreased cognitive and physical function, as low iron levels lead to less oxygen getting to tissues, including the brain. Iron deficiency is a concern for soldiers who often face unprecedented physical challenges leading to an energy deficit—using more calories than they consume—and low but near-constant levels of inflammation as their bodies work to grow stronger over time.
"Declines in iron status affect soldiers during training and also in the field," Hennigar said. "There is a compound effect from being in an energy deficit and having increased inflammation. Our work has shown that not consuming enough calories increases a hormone called hepcidin, which negatively impacts the amount of iron you can absorb from your diet."
Hennigar's work at PBRC is focused on discovering ways to minimize the decrease in iron absorption in soldiers by adding calories and iron supplements in different forms and at different times, such as when hepcidin levels might be lower.
"It's basically nutrient timing," Hennigar said. "And it's really important because if you don't have enough iron, you're going to feel lethargic and tired all the time, which will negatively impact your ability to think clearly and perform physical tasks. That's of great concern in the military, and also among athletes."
There is a theory that humans evolved the body's ability to prevent iron absorption during periods of inflammation and infection as a survival mechanism—not so much against strenuous exercise, but against potentially lethal pathogens, which need iron to become more virulent and infectious.
"The body is not able to distinguish between inflammation from an infection and inflammation from strenuous exercise," Hennigar said. "We think the decline in iron absorption with exercise is an unintended consequence."
Berryman's high-altitude study is not so much about being at high elevation as it is about being in an environment with less oxygen. Berryman will induce such an environment in Louisiana by having study participants sleep for eight weeks in a hypoxic, or low-oxygen, tent set up around their bed, along with a control group sleeping in tents with normal oxygen levels.
"All of our participants will have obesity, and our hypothesis is that those who sleep in 15 percent oxygen instead of the normal 21 percent will lose more weight and have improved metabolic health," Berryman said.
"What we already know from a previous study we did with USARIEM in young, healthy volunteers on Pikes Peak in Colorado, where the oxygen levels are about 12 percent, is that energy deficits led to weight-loss at a much higher magnitude than expected," Berryman said. "While we would have expected them to lose about seven pounds at sea level under the conditions of the study, instead they lost about 18 pounds over three weeks. It was amazing and got us thinking about how we might be able to use environmental extremes to help people with overweight or obesity or chronic diseases."
Berryman's work will establish baselines and develop a full dataset with health and nutrition data on active-duty military personnel. Such a dataset will be useful for future research studies at the intersection of defense and biomedicine, propelling work with the DoD even further.
"Claire and Steve bring additional scientific expertise we previously did not have at Pennington Biomedical and we're so happy to have them here working with us," Rood said. "We'll now be able to increase our reach in both number and kinds of projects."
James McClung, chief of USARIEM's Military Nutrition Division, also sees opportunities for increased collaboration between PBRC and the DoD.
"The applied experience that Berryman and Hennigar bring to the Pennington Biomedical team will facilitate and extend the longstanding collaborative relationship between USARIEM, the Department of Defense and PBRC," McClung said. "Their current and future work at PBRC will build upon recent discoveries, resulting in the development of tangible solutions to optimize and enhance Warfighter health and performance."