A new study conducted by Japanese researchers has linked the gut microbiomes of obese individuals to the development of tumors. Researchers from the Japanese Foundation for Cancer Research have found that obesity,
inflammation and the gut microbiome, together, provide the substrate which may enable the development of tumors.
They found that the gut microbiomes in rodents fed a high fat diet contain gram-positive bacteria which produce the metabolic end-product, Deoxycholic Acid (DCA), a proinflammatory bile acid metabolite. DCA was found to significantly contribute to liver inflammation of the mice that were exposed to the test. Furthermore, DCA-modified mouse hepatocytes resembled aging hepatocytes and these cells were highly sensitive to the effects of carcinogens.

The test has shown that the rodents that were exposed to carcinogens early in life were much more likely to develop liver cancer if they were then fed a high-fat diet. Eiji Hara, a senior author, and his colleagues made their discoveries that cell senescence and death was related to cancer development. It was conjectured that elimination of aging cells is critical to the prevention of cancer. It has also become clear recently that aging cells can sometimes release pro-inflammatory cytokines which can promote the development of cancer.

The team led by Hara found that a high-fat diet, alone, was not enough to significantly increase the risks of cancer rates in the animals. However, the scientists found that when the mice were given a Ras-activating drug (associated with oncogenic mutations) soon after birth, and then fed a high-fat diet, they eventually developed liver cancer. Only 5 percent of mice that were given low-fat diet developed mainly lung cancer, in contrast. These same researchers have also demonstrated that human obesity is associated with an increased proportion of intestinal gram-positive bacteria. The findings have led them to hypothesize that alteration of the gut microbiome might play a role in the development of obesity associated liver cancer.

The researchers found that the obese animals that were fed both high-fat and normal diets produced more DCA, and lower levels of DCA respectively, which means that low levels of DCA reduce the cancer rates in obese animals.
Researchers have concluded that these findings could support lifestyle changes that would enable the of obesity-associated cancer by controlling the levels of DCA or DCA-producing gut bacteria. The Japanese research team is undertaking epidemiological studies to find out whether individuals who are suffering from obesity, and develop cancer have high levels of DCA. The effects of DCA may not be limited to liver cancer only. They are testing whether another carcinogenic stimulus that might be affected by the gut microbiome and obesity may possibly be linked to colon cancer.
The research also concluded that a high-fat diet could also affect the production of bile acids by gut microbiome via inducing colitis. According to them., microbial bile acid metabolism should not be taken lightly as doing so may cause disastrous consequences for our health.

Information provided by Bioworld Today, June 28.
Information referenced from author Annete Breindl