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Doubt cast on gut bacteria triggering obesity

By Tim Sandle     Feb 16, 2015 in Science
San Jose - Some science studies indicate that the gut microbiome is the cause of obesity. However, one microbiologist is challenging this and says it is not so simple.
The link between obesity and the gut microbiome (the totality of microorganisms and their genetic interactions) and weight gain has been a buzz topic within microbiology. Several studies, including some I have reported on Digital Journal, argue that there is a strong correlation, perhaps even causation.
One microbiologist is challenging this - Katherine Pollard, PhD, a senior investigator at the Gladstone Institutes. Dr. Pollard raised her concerns at a recent meeting of the American Association for the Advancement of Science (AAAS) held in San Jose, CA on Friday. Dr. Pollard spoke at a symposium titled “Obesity and Microbiome.”
By deploying powerful computational tools, Katherine Pollard has re-examined several recent studies into obesity and bacteria. Her findings have revealed that there is no significant relationship between body mass index (BMI) and the types of microbes that reside in the intestines. Moreover, the pattern is actually one of great variability in that sometimes bacteria are associated with obesity and at other times with people of BMI's within the "acceptable" range.
In contrast, Dr. Pollard puts forward the alternative that it is the genetic make-up of the different strains of bacteria that are of greater importance. DNA in bacteria differs significantly, sometimes up to 30 percent. To apply this variation to the animal world, this is the difference between the genome of a human being and a mouse. This means that the examinations of gut bacteria should not simply stop at comparing different species. This is an important point because it is at the genetic level that the functionality of bacteria in terms of processing sugar and fat (key determinants of obesity) takes place.
On this basis, Katherine Pollard suggests that scientists should focus on changes to bacterial genomes, using the scientific field of metagenomics. This field has been advanced through the use of computer modelling and improved statistics.
In alternative research conducted at the Massachusetts General Hospital, a science team argue that obesity is in fact due to genes, environment and time.
More about Bacteria, Obesity, Intestines
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