Irish scientists have found that exercise may reduce the risk of obesity because of its positive impact on good bacteria in the gut

The health of our gut is garnering much attention of late, with a growing number of studies highlighting just how important it is to our overall wellbeing: it can have a powerful effect on anything from our mood to our immune system and our ability to fight disease. It’s also believed to be a key factor in tackling obesity.

The gut contains 10 times more bacteria than all of the cells in the entire rest of the body, and the health of gut flora not only aids digestion but also helps to regulate the metabolism. Specifically, a high microbial diversity in the gut has been associated with better overall health, whereas a low diversity of gut microbes has been linked to many diseases and syndromes, including obesity.

Numerous studies have looked at the impact diet has on gut health, and last month, scientists from Ireland revealed how exercise, alongside food intake, can help too. The findings were published in the international journal Gut*.

Researching rugby players
Researchers at the Alimentary Pharmabiotic Centre at University College Cork and the Teagasc Food Research Centre based their study on 40 Irish professional rugby players at the peak of training for the 2011 Rugby World Cup. Stool and blood samples were taken to measure the variety of bacteria in their guts. The players also completed a food questionnaire detailing the intake of 187 different items of food over a period of four weeks.

Their results were compared to a control group of 46 men. These men weren’t elite athletes, but they had the same mean age (29) as the rugby players. Half of them had an average BMI of 25 or lower, while the other half had a high BMI of 28 and above.

Exercise and diet impact
Researchers found the microbial diversity in the gut was significantly higher in the athletes compared to the control group, especially those with higher BMI scores. The levels of certain types of good bacteria were also greater in the rugby players. This included higher levels of akkermansiaceae – a type of bacteria associated with a lower risk of obesity. Athletes also had lower inflammatory and improved metabolic markers compared to the other men.

These gut microbial results correlated with two other studies: firstly, unsurprisingly, that the athlete group took part in much more physical activity than the control group – indicated by far higher levels of creatine kinase.

Secondly, dietary analysis showed that protein accounted for considerably more of the rugby players’ total energy intake (22 per cent), compared to the low BMI (16 per cent) and high BMI (15 per cent) control groups. The athletes’ fruit and veg intake was higher too.

“The athletes are an exceptional group in terms of their dietary intake, fitness/endurance and now, we know, in relation to their gut microbiota,” reports the Alimentary Pharmabiotic Centre. “This high diversity is linked with exercise and protein consumption and suggests that eating specific proteins and/or exercise can provide a means of increasing microbial diversity in the gut.”

Dr Paul Cotter, the principal research officer at Teagasc Food Research Centre told HCM: “We’re not sure which is more important – diet, exercise, or a combination of both. We hope follow-up studies will make this clearer. We’ll be looking at relatively unfit people to see if we can increase their microbial diversity [and, in turn, their gut health] through exercise and/or protein.

“The precise mechanism through which exercise might impact on the gut microbiota will also require further investigation. It could be related to the impact on the immune system, but it’s too early to say.”

*Clarke SF et al. Exercise and associated dietary extremes impact on gut mircobial diversity. Gut. June 2014