Healthy Life, October 2016

It’s Not All About Weight

by Pennington Biomedical Research Center

Have you heard the new phrase “skinny fat”?—it’s where you look trim and in shape, but your body is suffering from poor health, perhaps due to a poor diet, a lack of exercise or both.

“It can be dangerous,” says Dr. Annadora Bruce-Keller with Pennington Biomedical Research Center. Bruce-Keller studies the importance of the interrelationship between our guts and what we put into them, and the role that plays in the health of our body and brain.

“We want people to know that you can be healthy with a range of body types. Through our research we are finding that health is less about the number on the scale and more about how well your body is operating,” noted Bruce-Keller.

Dr. Annadora Bruce-Keller
Dr. Annadora Bruce-Keller

In one 2014 study, Bruce-Keller and her colleagues from Pennington Biomedical, Drs. J. Michael Salbaum and Hans-Rudolf Berthoud teamed up with scientists from LSU’s Health Sciences Center in New Orleans to learn more about the connection between nutrition and brain health. They found that the kinds of food we eat may have a significant impact not just on our body and its performance, but on our brain’s function too.

In their study published online in the journal Biological Psychiatry, Bruce-Keller and her fellow researchers discovered that an unhealthy gut microbiome stemming from a high fat diet may be bad for our brain. Our gut microbiome is the ecological community of bacteria that shares our body space, and it is formed in part by what we eat. What their study showed is that a microbiome shaped by an unhealthy, high fat diet increases anxiety, decreases memory and causes other negative cognitive changes.

These findings are part of groundbreaking new evidence that a high-fat diet can influence our gut bacteria enough to disrupt the way our brain works, and they also underscore the important relationship between the gut and the brain—something that could be a target for new drugs and other therapies in the future.

Their study is truly fascinating. The research team isolated the gut microbiota from obese mice that were fed a high fat diet and from healthy mice that were fed a lower fat control diet. The gut microbiome from the high fat diet was transplanted into one group of healthy, young mice, while the microbiome from the control diet group was transplanted into another identical group of young, healthy mice.

After running a battery of tests, Bruce-Keller noticed striking differences between the two groups of mice. While neither group became obese, the mice who received a gut microbiome from the high fat mice showed consistent signs of mental deficits, including decline in memory and an increase in compulsiveness and anxiety-based behavior compared to the mice given the healthy control diet.

Further testing revealed increased inflammation in the intestines of the mice with the high fat bacteria, and subsequently in their blood and brains, likely because the unhealthy microbiomes affected the structural integrity of the intestines leading to leaking and translocation of bacteria into the bloodstream, Bruce-Keller said.

While this study helps to take the focus off of weight as a primary indicator of health, it also suggests that it is the difference in bacterial diversity in our guts that makes a difference when it comes to behavior and brain chemistry—not the just presence of obesity or insulin resistance.

So what does this research mean for us when it comes to picking out our meals for the week at the grocery store or when we’re perusing the menu at a local restaurant?

Hans-Rudolf Berthoud
Hans-Rudolf Berthoud

Bruce-Keller says our gut microbiome changes by the hour, so we need to be mindful to form healthy habits of eating plenty of fruits and vegetables, more healthy fats and less saturated fat. In addition, she suggests eating yogurt with a probiotic, which can help balance the bacteria in the gut and can introduce healthy bacteria that may be missing in our diet. There are also plenty of over-the-counter probiotic supplements that your doctor may suggest.

What was Bruce-Keller about to eat for lunch when we spoke with her? She was preparing to enjoy a small bowl of fruit with kefir (which also aids “good” bacteria) on top. True to form, this scientist practices what she preaches.

Fellow researchers J. Michael Salbaum, Hans-Rudolf Berthoud contributed to this study, along with scientists from LSU’s Health Sciences Center in New Orleans (David A. Welsh, Christopher M. Taylor, Luo Meng and Eugene Blanchard, IV). You can read the complete study, entitled “Obese-type Gut Microbiota Induce Neurobehavioral Changes in the Absence of Obesity” online.