BODY WEIGHT HEAVILY INFLUENCED BY GUT MICROBES
Our genetic makeup
influences whether we are fat or thin by shaping which types of microbes thrive
in our body, according to a study by researchers at King's College London and
Cornell University.
By studying pairs of
twins at King's Department of Twin Research, researchers identified a specific,
little known bacterial family that is highly heritable and more common in
individuals with low body weight. This microbe also protected against weight gain
when transplanted into mice.
The results, published
today in the journal Cell, could pave the way for personalised
probiotic therapies that are optimised to reduce the risk of obesity-related
diseases based on an individual's genetic make-up.
Previous research has
linked both genetic variation and the composition of gut microbes to metabolic
disease and obesity. Despite these shared effects, the relationship between
human genetic variation and the diversity of gut microbes was presumed to be
negligible.
In the study, funded
by National Institutes of Health (NIH), researchers sequenced the genes of
microbes found in more than 1,000 fecal samples from 416 pairs of twins. The
abundances of specific types of microbes were found to be more similar in
identical twins, who share 100 per cent of their genes, than in non-identical
twins, who share on average only half of the genes that vary between people.
These findings demonstrate that genes influence the composition of gut
microbes.
The type of bacteria
whose abundance was most heavily influenced by host genetics was a recently
identified family called 'Christensenellaceae'. Members of this
health-promoting bacterial family were more abundant in individuals with a low
body weight than in obese individuals. Moreover, mice that were treated with
this microbe gained less weight than untreated mice, suggesting that increasing
the amounts of this microbe may help to prevent or reduce obesity.
Professor Tim Spector,
Head of the Department of Twin Research and Genetic Epidemiology at King's
College London, said: 'Our findings show that specific groups of microbes
living in our gut could be protective against obesity -- and that their
abundance is influenced by our genes. The human microbiome represents an
exciting new target for dietary changes and treatments aimed at combating
obesity.
'Twins have been
incredibly valuable in uncovering these links -- but we now want to promote the
use of microbiome testing more widely in the UK through the British Gut
Project. This is a crowd-sourcing experiment that allows anyone with an
interest in their diet and health to have their personal microbes tested
genetically using a simple postal kit and a small donation via our website . We want thousands to join
up so we can continue to make major discoveries about the links between our gut
and our health.'
Ruth Ley, Associate
Professor at Cornell University in the United States, said: 'Up until now, variation
in the abundances of gut microbes has been explained by diet, the environment,
lifestyle, and health. This is the first study to firmly establish that certain
types of gut microbes are heritable -- that their variation across a population
is in part due to host genotype variation, not just environmental influences.
These results will also help us find new predictors of disease and aid
prevention.'
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