Belly fat has been singled out for many years as an enemy of health. It’s been linked to heart risk, metabolic syndrome, and type 2 diabetes. But abdominal fat may have a benefit after all, actually two benefits. It appears to help regulate the immune system and sends cells to the site of injury to help heal damaged tissue.

Understanding more about the effects of omentum cells on the immune system could lead to better immunosuppressive drugs after organ transplants, or to treat people who have autoimmune diseases like Crohn’s disease.

A new study looked at the function of cells of the omentum, the vast, fatty network of tissue that sheathes most of the abdominal organs. The researchers exposed omentum cells to T cells from the immune system. T cells typically multiply themselves when they come into contact with antibodies, but when they were exposed to omentum cells, they did not multiply, suggesting that omentum cells may secrete a substance that turns off this part of the immune response. The authors suggest that understanding more about the effects of omentum cells on the immune system could lead to better immunosuppressive drugs after organ transplants, or to treat people who have autoimmune diseases like Crohn’s disease.

In another part of the experiment, the team learned that omentum also contains mesenchymal stem cells, which are able to differentiate into various cell types, including lung cells and bone cells. This type of stem cell is also able to migrate to injured tissue to help repair it by generating new cells.

"We now have evidence that the omentum is not just fat sitting in the belly," said study author Makio Iwashima in a news release. Far from sedentary tissue, the omentum actually appears to serve several purposes that help heal the body and generate multiple tissue types. This is not to say that we should try to increase our stores. Rather it points to the incredible capabilities of the body’s tissues, and the fact that even apparently “useless” tissue can serve some extremely valuable purposes.

The research was carried out by a team at the Loyola University Chicago’s Stritch School of Medicine and published in the journal PLoS One.