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Researchers at Stanford University found that feed­ing round­worms the monoun­sat­u­rated fat in olive oil pro­longed their lifes­pan. Given the sim­i­lar­i­ties in monoun­sat­u­rated fat metab­o­lism between round­worms and humans, they believe it’s pos­si­ble the longevity effect could extend to people.

The authors were sur­prised the monoun­sat­u­rated fat that extended life also caused the round­worms to gain weight. As calo­rie restric­tion is asso­ci­ated with longevity, they didn’t antic­i­pate that an accu­mu­la­tion of this par­tic­u­lar kind of fat would be ben­e­fi­cial in that regard. However, since the pudgy round­worms fed the monoun­sat­u­rated fat lived longer than their thin­ner coun­ter­parts, it indi­cated a cer­tain type of fat buildup could be healthful. 

“We have known for some time that meta­bolic changes can affect lifes­pan, but we expected the long-lived ani­mals in our study would be thin­ner,” said senior author Anne Brunet, pro­fes­sor of genet­ics. ​“Instead, they turned out to be fat­ter. This was quite a surprise.” 

The study orig­i­nated as an inves­ti­ga­tion into the role of epi­ge­net­ics in lifes­pan reg­u­la­tion. Epigenetics is the process by which gene expres­sion changes in response to envi­ron­men­tal stim­uli. The researchers’ objec­tive was to deter­mine how epi­ge­netic com­plexes, which mod­ify the pro­teins that pack­age DNA (also known as his­tones), might influ­ence round­worm meta­bolic changes in a man­ner that affects lifespan. 

With this intent, Brunet and lead author Graduate stu­dent Shuo Han eval­u­ated the effect of block­ing the expres­sion of an epi­ge­netic com­plex called COMPASS on the metab­o­lism of round­worms. The COMPASS pro­teins are known to change the chem­i­cal com­po­si­tion of pro­teins that pack­age DNA (his­tones) in a way that can affect whether or not genes are expressed. After they blocked the expres­sion of COMPASS pro­teins, the worms lived 30 per­cent longer. Han wanted to under­stand why. 

“We thought that this epi­ge­netic mod­i­fi­ca­tion change caused by COMPASS defi­ciency might mimic dietary restric­tion,” Brunet said. ​“So we began look­ing at the metab­o­lism and fat con­tent of the worms defi­cient for COMPASS.” 

Han observed that the round­worms with the blocked COMPASS pro­teins not only lived longer, but they also accu­mu­lated fat in their intestines. Analysis of the fat revealed it was pri­mar­ily com­posed of monoun­sat­u­rated fatty acids, which is the type of fat con­tained within olive oil, avo­ca­dos, and nuts. Han found that sup­press­ing the COMPASS pro­teins caused a rise in the expres­sion of enzymes that change sat­u­rated fats into monoun­sat­u­rated fat in the intestines. Because monoun­sat­u­rated fats have been linked to a lower risk of car­dio­vas­cu­lar dis­ease and dia­betes, the find­ing was intriguing. 

In an effort to ascer­tain if the accu­mu­la­tion of monoun­sat­u­rated fats affected lifes­pan, the researchers fed both monoun­sat­u­rated and polyun­sat­u­rated fats to the worms. ​“We found that the monoun­sat­u­rated fats accu­mu­lated in the worms’ guts and increased their life span even when COMPASS was not mutated. In con­trast, polyun­sat­u­rated fats did not have the same effect,” said Brunet. 

Prior research shows the type of fat con­sumed has a much greater influ­ence on health than the quan­tity, and the recent exper­i­ment builds upon what is known on the topic. ​“Our study sug­gests that fat com­po­si­tion rather than fat level is impor­tant for longevity and that not all fatty acids have the same effect on health,” Brunet told Olive Oil Times. 

Currently, the research team is seek­ing the answer to why monoun­sat­u­rated fat buildup appears to extend life. While they have yet to learn the mech­a­nism of action that under­lies the ben­e­fit, this recent dis­cov­ery pro­vides more evi­dence that the fat in extra vir­gin olive oil is most healthful. 

The study was pub­lished in the jour­nal Nature.

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