July 30, 2014
Gender Differences In How Diet Affects Our Gut Microbes
April Flowers for redOrbit.com - Your Universe Online
It has been evident for a while that men and women react to diet differently. Men lose weight easier than women, men need more calories than women because of muscle mass, and there are even differences in eating styles.
The findings, published in Nature Communication, indicate that therapies designed to improve health and treat disease through nutrition need to be tailored for each gender.
The data for this study was collected from the gut microbes of mice and two species of fish. The team also performed an in-depth analysis of data collected on humans by previous research teams. In fish, and in humans, the researchers discovered that diet affected the microbiota of males and females in different manners. For example, in some instances, different species of microbes would dominate. In other instances, one sex would have a higher diversity of bacteria than the other.
Scientists have only recently begun to appreciate the vital role played by the human microbiome, which consists of all the bacteria that live in or on a person's body. The gut microbiome alone is made up of hundreds, or perhaps thousands, of different species of microbes, each varying in abundance.
Human health can be affected in a very real way by the variety and number of microbes in the gut, which is determined by a mixture of genetics and diet. Researchers have been able to link obesity, diabetes and inflammatory bowel disease to low diversity of bacteria in the human gut.
A lot still needs to be understood about which species, or combination of species, is the best for human health. To gain this knowledge, scientists need to know how various combinations of diet, genetics and environment affect the microbes. Unfortunately, most studies focus on a single factor and do not account for how the variables interact.
"Our study asks not just how diet influences the microbiome, but it splits the hosts into males and females and asks, do males show the same diet effects as females?" said Daniel Bolnick, professor in The University of Texas at Austin's College of Natural Sciences.
Despite identifying the gender differences in gut microbiota, the data used for this study does not lend itself to specific diet tips because it is organized into complex clusters of disparate factors.
"To guide people's behavior, we need to know what microbes are desirable for people," said Bolnick. "Diet and sex do interact to influence the microbes, but we don't yet know what a desirable target for microbes is. Now we can go in with eyes open when we work on therapies for gut microbe problems, as many involve dietary changes. We can walk into those studies looking for something we weren't aware of before. All along we treated diet as if it works the same for men and women. Now we'll be approaching studies of therapies in a different way."
It still isn't clear why males and females would have different reactions to changes in diet, but a couple of possibilities present themselves. For one, the hormones associated with gender could influence gut microbes, pushing the body's environment to favor one strain over another. Another explanation could be found in the fact that the sexes differ in how their immune systems function, which could change which microbes live and die in the gut microbiome.
Bolnick notes that the one exception in his study was in the mice. The researchers found a tiny difference between males and females, but for the most part, the gut microbiomes of both sexes responded to diet in the same manner. This finding, which raises questions about how well mice studies can be generalized to other species, could have a great impact on future studies, as most dietary research is conducted on mice.
"This means that most of the research that's being done on lab mice — we need to treat that with kid gloves," said Bolnick.
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