Gut bacteria could be heavily linked to obesity risk

A team of scientists have found that ‘good’ gut bacteria could play a key role in determining if you become or overweight or obese and help to protect against suffering from a heart attack or stroke – medical problems often caused by being overweight.

The findings from two studies demonstrate that by adhering to a diet rich in fibre, this could help to alter the makeup of these germs, and allow people to more easily shed excess weight.

“We know gut bacteria affect health and obesity, but we don’t know exactly how,” commented Dusko Ehrlich, one of the co-authors of the two new studies and coordinator of the International Human Microbiome Standards project.

He added: “People who put on the most weight lack certain bacterial species or have them at very low levels. This opens ways to develop bacterial therapies to fight weight gain.”

There are many health experts who are adamant it is the gut that is the primary area that is crucial in regards to weight gain or weight loss.

Jeffrey Cirillo, a professor at Texas A&M Health Science Center’s department of microbial pathogenesis and immunology, says: “It is now well known that bacteria in our gut play an important role in our health and well-being, possibly as important as our own immune response and proper nutrition. This means that disruption of the bacteria in our gut by use of antibiotics or eating foods that help only particular bacteria grow can have effects upon our entire bodies.”

Back in March a study was published in the journal Science Translational Medicine, explaining that gastric bypass surgery resulted in weight loss (in mice) due to changes in their intestinal bacteria.
The new studies were published yesterday in the journal Nature, and in one of them, the researchers looked at gut bacteria of 169 Danish people who were obese and 123 Danish people who were not obese.

Those obese were generally found to have ‘less diverse’ gut germs, with more abnormalities with regards to metabolism. Those with a less diverse group of germs also tended to put on weight.
Cirillo says that although there is some uncertainty how obesity and bacteria are linked, from the research it would seem that the germs themselves have metabolisms which impact the overall metabolism within the human of where they live.

Study co-author Ehrlich says there may be a practical application to be had from the research, commenting: “The study lays ground for a simple test, which should tell people what their risk for developing obesity-linked diseases is,” If they are found to be at risk, diet changes may be necessary he says.

For a second study, researchers tracked the gut bacteria of 49 overweight and obese people as they were put on diets that were low-fat and low-calorie in an attempt to lose weight, but were also high in protein and included foods rich in fibre such as fruit and vegetables. The participants subsequently seemed to benefit from a change in the bacterial makeup within their guts because of the diet.

“Although these are relatively early and small studies on the topic, they suggest that management of our own diets can improve the richness of the flora within our guts and decrease our chances of becoming obese,” said Cirillo. “This does not mean that changes in diet will be effective for all people or that they can prevent obesity no matter how much someone eats, but that they can help the situation.”

Could obesity and type 2 diabetes be treated with gut bacteria?

A particular type of gut bacteria has been found to help reverse obesity and type 2 diabetes in animal studies; perhaps paving the way for new treatments for both health problems. Type 2 diabetes is most commonly connected to obesity and maintaining a healthy weight is one of the most effective ways of reducing the risk of developing the disease.

The Research, published in Proceedings of the National Academy of Sciences, demonstrates how mice were given a broth that contained a single species of bacteria, and there were subsequently huge benefits to their health.

The bacteria studied and which was administered to the mice, was the Akkermansia muciniphila – usually comprising of around 3-5% of gut bacteria. However, these levels are found to decrease in obese individuals.

Professor Patrice Cani and his team at the Catholic University of Louvain, in Belgium, wanted to focus firstly on mice that were eating a lot of fat and were obese and/or had type 2 diabetes. Researchers noted that the mice quickly gained two to three times extra fat compared to the leaner mice that were eating a more ‘normal’ diet.

However, giving the unhealthier mice oligofructose prebiotics – a dietary supplement that boosts the number of beneficial bacteria – this helped restore the Akkermansia muciniphila back to healthy levels.

These mice then gained a quicker metabolism and the rodents found themselves losing excess weight, reduced inflammation and lowered their insulin resistance; a symptom associated with type 2 diabetes.

The bacteria had worked at thickening the gut’s mucus barrier. This prevents some material from being transferred into the blood from the gut. In addition, the Akkermansia muciniphila had managed to alter chemical signals emanating from the digestive system, leading to changes in the processing of fat in other areas of the body.

Interestingly, similar findings were also achieved when researchers included a certain type of fibre in the diet of the mice and levels of Akkermansia muciniphila then increased.

Prof Cani commented on the study findings, saying: “Of course it is an improvement, we did not completely reverse the obesity, but it is a very strong decrease in the fat mass. I don’t think it’s feasible that you can eat cream cakes and chips and sausages all day long and then eat bacteria to reverse all that. It is the first demonstration that there is a direct link between one specific species and improving metabolism.”

Prof Cani said it was ‘surprising’ how merely one species of gut bacteria has such a positive impact when there are actually thousands within the gut, adding that the bacteria-based therapy may hopefully be utilised as a prevention method or as a treatment option for obesity and type 2 diabetes in the near future.