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.'
For further information please contact Jack Stonebridge, Press Officer at King's College London.
The study was also supported by the National Institute for Health Research (NIHR) BioResource Clinical Research Facility and Biomedical Research Centre based at Guy's and St Thomas' NHS Foundation Trust and King's College London.
King's College London is one of the top 20 universities in the world (2014/15 QS World University Rankings) and the fourth oldest in England. It is The Sunday Times 'Best University for Graduate Employment 2012/13'. King's has nearly 26,000 students (of whom more than 10,600 are graduate students) from some 140 countries worldwide, and more than 7,000 staff. The College is in the second phase of a £1 billion redevelopment programme which is transforming its estate.
King's has an outstanding reputation for providing world-class teaching and cutting-edge research. In the 2008 Research Assessment Exercise for British universities, 23 departments were ranked in the top quartile of British universities; over half of our academic staff work in departments that are in the top 10 per cent in the UK in their field and can thus be classed as world leading. The College is in the top seven UK universities for research earnings and has an overall annual income of nearly £590 million.
King's has a particularly distinguished reputation in the humanities, law, the sciences (including a wide range of health areas such as psychiatry, medicine, nursing and dentistry) and social sciences including international affairs. It has played a major role in many of the advances that have shaped modern life, such as the discovery of the structure of DNA and research that led to the development of radio, television, mobile phones and radar.
King's College London and Guy's and St Thomas', King's College Hospital and South London and Maudsley NHS Foundation Trusts are part of King's Health Partners. King's Health Partners Academic Health Sciences Centre (AHSC) is a pioneering global collaboration between one of the world's leading research-led universities and three of London's most successful NHS Foundation Trusts, including leading teaching hospitals and comprehensive mental health services. For more information, visit: www.kingshealthpartners.org.
British Gut is the UK's largest open-source science project to understand the microbial diversity of the human gut. Launched in October 2014, it is a collaboration between the Department of Twin Research at King's College London and American Gut. For more information visit the website: http://www.