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Your Diet, Your Brain and Your Microbiome

What you eat can affect your ability to adapt and adjust to changing situations in your day-to-day environment, at least if you’re a mouse. New research from Oregon State University suggests that diets high in fat and sugar have an undesirable effect on the microbiome, the 100 trillion or so microorganisms that populate our digestive system. And that influence seems to impact the brain’s ability to adapt and adjust to new problems, a trait known as cognitive flexibility. Although this study was done in mice (which the researchers said are a “good model” for humans on a variety of topics), it suggests that these particular diets can affect the way we respond to unexpected changes. The real-world example lead investigator Kathy Magnusson gave was how quickly you would adapt if you were driving home and your usual route was closed. No problem plotting an alternate course as a solution if you have normal cognitive flexibility. If not, your trip home could be pretty stressful. With the mice, four weeks on a high sugar or high fat diet affected the way they performed on a variety of challenging tests compared to animals on a normal mouse diet. One of the most pronounced changes seen was in cognitive flexibility. The study was done with young mice. Dr. Magnusson said the effect of the high sugar or high fat diet might be more dramatic in older animals (or humans).

 

My take: These new findings mirror the results of other studies about the impact of fat and sugar on cognitive function and behavior, suggesting that some of these problems may be linked to dietary influences on the microbiome. We’re just beginning to understand the health consequences of our microbiomes, but based on what we know so far, they are becoming increasingly unbalanced in this country compared to other populations that eat traditional diets. This is likely due to growing reliance on processed products in addition to regular exposure to antibiotics from medical treatment and residues in foods. These changes in the microbiome may underlie an increased incidence of a wide range of diseases and conditions including psychological and behavioral disorders. 

Heartburn Drugs May Interfere with Your Microbiome

The drugs in question are proton pump inhibitors (PPIs), including Prilosec and Nexium. A study from the Mayo Clinic found that taking the drugs frequently or for long periods may affect the balance of bacteria in your digestive system (known collectively as your microbiome), which in turn may increase the risk of infection, particularly with the bacterium Clostridium difficile, which causes severe and often debilitating diarrhea. In addition to this risk, PPI's have been linked to vitamin deficiencies, bone fractures and increased risk of pneumonia. The study authors didn't advise that people who take the heartburn drugs should give them up, but they did caution that PPIs should be used at their lowest effective dose and that patients who take them should periodically consider attempts to discontinue them. PPIs are frequently recommended for gastrointestinal reflux disease (GERD) characterized by heartburn that occurs twice a week or more. The study was a small one, with only 9 participants who took 20 or 40 milligrams of the drug daily for 28 days and provided stool samples for examination, allowing researchers to document changes in the bacterial balance of their microbiomes. The investigators noted that a larger study is warranted to further investigate the effect of the drugs on the microbiome. In addition to drugs such as PPI's, you can address GERD by eating smaller portions, losing weight, avoiding lying down for two hours after eating, and abstaining from alcohol, cigarettes and foods that commonly trigger heartburn.

Is Your Microbiome In Charge?

Is it possible that the hundred trillion microbes that make up the microbiome in the human gut "know" what nutrients they need, and in seeking them influence our dietary choices? This interesting theory holds that, in some cases, our intestinal flora nudges us toward fat or sugar and possibly obesity. A new review of recent scientific literature concludes that our microbes actually can trigger cravings, as their attempts to receive more of the foods they need for growth affect our eating behavior. The authors of the review write that it is “unclear” how the microbes might do this, but suggest that they may influence food choices by releasing signaling molecules into the gut, which has links to the immune system, endocrine system and nervous system. Another possibility: according to researchers from the University of California, San Francisco, Arizona State University and the University of New Mexico, gut bacteria may sway our eating decisions in part by acting through the vagus nerve, which connects 100 million nerve cells from the digestive tract to the base of the brain. On the upside, the reviewers note that our food choices can alter the microbiome within 24 hours. Better yet, the authors write that microbiota “are easily (manipulated) by prebiotics, probiotics, antibiotics, fecal transplants, and dietary changes…(offering) a tractable approach to otherwise intractable problems of obesity and unhealthy eating.”

My take? We know that our individual microbiomes are very different from one another, and it appears our own unique balance of organisms influences our health. Recent research suggests, however, that our microbiomes in general are becoming increasingly unbalanced for a number of reasons, including diets heavy in processed foods and increased exposure to antibiotics via both medical treatments and residues in foods from animals treated with the drugs. This review suggests that it's likely we ultimately have the power to control our own microbiomes, instead of the other way around.

Sources:
“Athena Aktipis, Carlo Maley, Joe Alcock, “Is eating behavior by manipulated the gastrointestinal microbiota? Evolutionary pressures and potential mechanisms.” BioEssays doi: 10.1002/bies.201400071

Exercise for a Better Microbiome

Exercise could boost the diversity of the microbes in your gut, and eating a lot of protein might help, as well. A diverse “microbiome,” as this population of microbes is called, is necessary for optimal functioning of our immune systems, and supports overall health. By examining blood and stool samples, researchers in Ireland were able to compare the microbial diversity of professional rugby players with those of healthy men, some of normal weight and some overweight. They found that the athletes, overall, had greater gut diversity than the other men, which they attributed to the players’ strenuous exercise and diets that were higher in protein (22 percent of calories) compared to 15 to 16 percent of calories from protein the other men consumed daily. The athletes’ microbiomes were not only more diverse, the researchers reported that they were more populous than those of the other men in the study, and included higher levels of a species of bacteria associated with lower rates of obesity and obesity-related disorders. Whether exercise or protein or both were responsible for the diversity of the rugby players’ microbiomes remains to be confirmed by future studies, but this investigation certainly showed an intriguing association.

Sources:
Siobhan Clark and Orla O’Sullivan, et al, “Exercise and associated dietary extremes impact on gut microbial diversity,” Gut, doi: 10.1136/gutjnl-2013-306541

What’s Your Take On The Microbiome – Allergy Connection? (Poll)

A recent Q&A discussed microbiome in the gastrointestinal tract and how it may be connected with allergies: Do the Bugs in Your Belly Cause Allergies? Check out the article and let us know your opinion on the connection between the microbiome and allergies.