Professor Explores Nutritional Complications of Bariatric Surgery

Nana Gletsu-Miller

Nana A. Gletsu-Miller, PhD

Associate Professor, Department of
Nutrition Science


PhD, University of Alberta, Edmonton, Canada, 1998 Nutrition and Metabolism

BSc, University of Saskatchewan, Saskatoon, Canada, 1990 Biochemistry, Honors


Associate Professor of Nutrition Science, Purdue, 2011-present

Assistant Professor of Surgery and Assistant Professor of Hubert Department of Global Health, Emory University, Atlanta, 2006-11

Research Instructor of Surgery, Emory University, 2001-06

Postdoctoral Fellow of Pathology, Emory University, 1998-2001


NIH/Research Supplements for Under Represented Minorities Fellowship, 1998-2001

Graduate Student Research Award from American Society for Nutritional Sciences, 1998


The Obesity Society, 2003-present

American Society for Nutrition,

Canadian Nutrition Society, 1996-present

Bariatric surgery has become a popular weight-loss option with more than 200,000 surgeries performed in the U.S. each year. Over 2 million patients have undergone the procedure.

"There are not many other proven weight loss programs for people who have 100 or more pounds to lose," stated Nana Gletsu-Miller, associate professor of nutrition science. "And the surgery works. In a month people lose about 10 percent of their body weight and 25 percent over six months." Most patients are able to maintain a lower body weight over the long term.

With bariatric surgery, the procedure makes the stomach smaller; some procedures also allow food to bypass part of the small intestine and to go directly to the lower intestine. The operation allows the patient to feel full with less food than before the surgery when the stomach was its original size. Patients lose weight, thus reducing serious health risks, such as heart disease, diabetes and stroke.  However, there are some nutritional drawbacks to the surgery. A smaller stomach limits digestion, some nutrients are not absorbed as well in the lower intestine, and because patients are eating less, fewer essential nutrients and vitamins are available in the body.

Research Focus

Gletsu-Miller's research studies the impact of weight-loss surgery on overall health, and she wondered, "Are these patients trading one set of problems for another?"

"With the weight loss, patients often feel so good after surgery they stop going to their doctors for follow-up and monitoring. Over time we see nutritional deficiencies," she explained. "Patients can lack iron, vitamin D, some B vitamins, zinc, and copper resulting in a range of issues including fatigue, anemia, hair loss or neurological problems."

Surgery itself only helps with weight loss for a year or two. Outcomes of Gletsu-Miller's work include helping post-surgical patients optimize nutritional health. In addition, bariatric surgery is a useful tool in research. "It is fascinating to study the connection between obesity and some diseases by examining the impact of bariatric surgery. We know obesity leads to cancer and heart disease, but why? What are the molecular reasons? The best way to study these things is to study people who lose weight."

Part of the work, she added, is to share data with Purdue collaborators Kolapo Ajuwon, associate professor of animal sciences, and Connie Weaver, distinguished professor of nutrition science. Together the researchers study the mechanisms that link excess body fat and diseases such as diabetes, heart disease, cancer and metabolic syndrome as well as how to improve the bioavailability of nutrients. "We use clinical protocols and also molecular assays. We try to translate observations from human studies to data that we obtain in the laboratory. We can use our understanding of what is going on to help others.

"Bariatric surgery patients develop the same nutritional problems such as iron, zinc, and protein deficiency that we see in people around the world. So, what we find from research with bariatric surgery patients can be applied to other populations that are at risk."

Gletsu-Miller was drawn to this research "randomly" 13 years ago while at Emory University. She was studying obesity using mouse models when a physician friend mentioned that surgeons were beginning to acknowledge nutritional issues after bariatric surgery. That piqued her interest, and she began to study post-surgery patients as part of her research. "It was exciting to be part of a collaboration of clinicians and researchers. I continue to benefit from multidisciplinary research that includes physician scientists."

What's Next?

The author of dozens of scholarly articles acknowledged there are more important questions to answer. Can we improve nutritional outcomes following surgery through vitamin and mineral supplementation? What are the appropriate formulations and doses?  What are the drawbacks of high dose supplements?

Educating post-surgery patients on the nutritional risks remains a key to optimal health, said Gletsu-Miller. "Patients should get routine nutritional check-ups after surgery, and always continue to take vitamins and minerals. It is important to be aware of symptoms and to not ignore them."

College of Health & Human Sciences, 700 W. State Street, West Lafayette, IN 47907, (765) 494-4600

2016 Purdue University | An equal access/equal opportunity university | Copyright Complaints | Maintained by College of Health & Human Sciences

If you have trouble accessing this page because of a disability, please contact College of Health & Human Sciences at