By Mary Elizabeth Dallas
TUESDAY, June 10, 2014 (HealthDay News) -- Exercise can increase the diversity of bacteria found in the gut, possibly boosting the immune system and improving long-term health, British researchers report.
High levels of dietary protein might have the same effect, according to their study, published June 9 in the journal Gut.
"Understanding the complex relationship among what we choose to eat, activity levels and gut microbiota richness is essential," Dr. Georgina Hold, of the Institute of Medical Sciences at Aberdeen University in Scotland, said in a journal news release.
"As life expectancy continues to increase, it is important that we understand how best to maintain good health. Never has this been more important than in respect of our resident [gut] microbiota," she added.
In conducting the study, the researchers examined the blood and stool samples of 40 professional rugby players in the middle of a rigorous training program. The athletes were chosen for the study because intense exercise regimens are often associated with extreme diets. The researchers used the samples collected from the men to determine the variety of bacteria in the players' guts.
The rugby players' samples were then compared to samples taken from 46 similar men who were healthy, but not athletes. Half of these men had a normal body-mass index (BMI) -- a measure that can help determine if someone is a normal weight for their height. The rest had a higher-than-normal BMI.
All of the men answered questions about 187 types of food, including how much of them they ate in the past four weeks and how often. The men were also asked about their typical levels of physical activity.
The study revealed the athletes had higher levels of a specific enzyme that signals muscle or tissue damage. These men also had lower levels of inflammatory markers and a better metabolic profile than the men in the "non-athlete" control group with a higher BMI.
The research doesn't prove, however, that their workouts and eating habits made the athletes healthier than the other men.
The athletes, the researchers said, also had greater diversity in their gut bacteria than the other men. This was particularly true when compared to the men with a high BMI.
Not only were there more types of bacteria, they were also found in greater numbers in the athletes' guts. And the athletes had much higher levels of one particular species of bacteria linked to reduced rates of obesity and obesity-related disorders, the researchers said.
The researchers found the athletes ate more of all of the food groups than the non-athletes. Protein (mostly meat) accounted for 22 percent of their energy intake, compared to 15 percent to 16 percent among the non-athletes. The rugby players also consumed protein supplements and ate many more fruits and vegetables than the non-athletes. The non-athletes ate more snack foods.
"Our findings indicate that exercise is another important factor in the relationship between the microbiota, host immunity and host metabolism, with diet playing an important role," the study authors wrote.