Fatty find

A spare tire may be life-extending — as long as it’s sporting the right kind of fat. Stanford Medicine researchers have found that feeding roundworms monounsaturated fatty acids — the kind found in olive oil, nuts and avocados — stimulates a fatty buildup that appears to extend their lives. 

Because many species share similar patterns of fat metabolism, it’s possible that the findings could extend to other animals, including humans, the researchers believe.

“We expected the long-lived animals in our study would be thinner,” says Anne Brunet, PhD, professor of genetics. “Instead, they turned out to be fatter. This was quite a surprise.”

Brunet is the senior author of the study, published online April 5 in Nature. Graduate student Shuo Han is the lead author.

The researchers made their discovery while exploring epigenetics — a process by which organisms modulate their gene expression in response to environmental cues — and its effect on life spans. The animal under scrutiny was Caenorhabditis elegans, a roundworm often used for longevity studies due to its short life span and ease of care.

Han and Brunet noticed that certain worms in their study not only lived longer than their peers, but they also accumulated fats, primarily monounsaturated fatty acids, in their guts.

Humans with diets rich in monounsaturated fats have been shown to have a reduced risk for heart disease and diabetes, and some studies have shown that centenarians store more monounsaturated fat than non-centenarians.

“We wanted to know whether this accumulation of monounsaturated fats was important to life span,” Brunet says, “so we fed both monounsaturated and polyunsaturated fats directly to the worms. We found that the monounsaturated fats accumulated in the worms’ guts and increased their life span. In contrast, polyunsaturated fats did not have the same effect.”

The researchers are now trying to understand how the monounsaturated fatty acid accumulation might lead to a longer life. Some possibilities include the ready availability of quick energy in the stored fat, or the fact that the fat may provide an accessible source of lipid-based signaling molecules to facilitate communication between cells or tissues. Alternatively, the monounsaturated fats may help preserve the fluidity of the lipid membranes that enclose and protect cells.