Exercise boosts diversity of gut bacteria
11 June 2014
Exercise boosts the diversity of the bacteria found in the gut,
according to a study of professional rugby players published online
in the journal Gut.
This may have implications for overall long term health, says the
author of a linked editorial. Reduced variation in gut microbes (microbiota)
has been linked to obesity and other health problems, while
increased diversity has been associated with a favourable metabolic
profile and immune system response.
The researchers analysed the DNA of microbiota in faecal samples
and creatine kinase levels in blood samples of 40 professional rugby
players in the midst of a rigorous training programme to assess the
range of microbiota they were hosting in their guts. Elite athletes
were chosen for the study on the grounds that extremes of exercise
are often associated with extremes of diet. Their samples were
compared with the same samples taken from 46 healthy men who were
not professional athletes, but who matched the physical size and age
of the rugby players.
Half of the comparison group had a normal body mass index (BMI)
of 25 or less; and half had a high BMI of 28 or more. All study
participants completed a food frequency questionnaire, detailing how
much and how often they had eaten 187 food items over the preceding
four weeks. And all were asked about their normal levels of physical
Despite having significantly higher levels of creatine kinase, or
CK for short — an enzyme that indicates muscle/tissue damage — the
athletes had lower levels of inflammatory markers than any of the
men in the comparison group. They also had a better metabolic
profile than the men with a high BMI.
But they had a significantly wider range of gut microbiota than
men in the comparison group, particularly those with a high BMI. And
the numbers of several microbial types (taxa) were also higher. For
example, they had significantly higher proportions of 48 taxa than
the men with high BMI, and of 40 taxa than the men with normal BMI.
In particular, they had much higher proportions of
Akkermansiaceae, a species of bacteria that is known to be linked to
lower rates of obesity and associated metabolic disorders.
Analysis of the dietary habits of all the study participants
showed that the rugby players ate more of all the food groups. And
protein accounted for considerably more of their energy intake (22%)
than it did in the comparison group (15-16%).
Meat and meat products made up the bulk of this, but the athletes
also took a lot of protein supplements, and they ate far more fruit
and vegetables, and far fewer snacks than their counterparts.
“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,” conclude the
In a linked editorial, Dr Georgina Hold, of the Institute of
Medical Sciences, Aberdeen University, points out that our guts are
colonised by trillions of bacteria, the composition of which has
been implicated in many conditions and is known to determine how
well we harvest the energy from the foods we eat.
“Understanding the complex relationship among what we choose to
eat, activity levels and gut microbiota richness is essential,” she
writes. “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 microbiota,” she
Clarke SF et al. Exercise and associated dietary
extremes impact on gut microbial diversity. Gut 2014;0:1–8.