Scientists from the UK and Hungary have run various experiments to verify the claim of US researchers that a certain gene is responsible for the increase of lifespan, as shown in some test organisms. Their results show, in fact, that the so called “longevity gene” allegedly responsible for the generation of an anti-aging protein doesn’t affect longevity at all.

The round­worm C. ele­gans, used in some ag­ing studies. (c) Wikimedia Commons, National Human Genome Research Institut

The round­worm C. ele­gans, used in some ag­ing studies. (c) Wikimedia Commons, National Human Genome Research Institut

The substance controlled by the gene, called sirtuin, has since been the subject of heavy marketing campaigns by cosmetic companies who advertised sirtuin enhancing anti-aging products, like anti-wrinkle creams or anti-aging pills.

The initial research which came with the longevity gene conclusion based their work on the study of yeast, nem­a­tode worms and fruit flies, of­ten used as mod­els for the bi­ol­o­gy of hu­man aging. Their initial conclusion was that when the or­gan­is­ms over­pro­duced sir­tuin, they lived long­er, by as much as 50 per­cent in the case of nem­a­todes. Another connection to increased lifespan was found to be dietary restrictions, which scientists claimed stimulated the production of sirtuins.

A subsequent research, however, published in this week’s edition of the jour­nal Na­ture, led by Da­vid Gems and col­leagues at Uni­vers­ity Col­lege Lon­don, shows that there isn’t any conclusive evidence that links sirtuin to enhanced lifespan.

“These re­sults are very sur­pris­ing. We have re-ex­am­ined the key ex­pe­ri­ments link­ing sir­tuin with longe­vity in an­i­mals and none seem to stand up to close scru­ti­ny. Sir­tu­ins, far from be­ing a key to longe­vity, ap­pear to have noth­ing to do with ex­tending life,” Gems said. “But I think this is good news in a way: af­ter all, re­vis­ing old ideas can be as im­por­tant as pre­sent­ing new ones to as­sure sci­en­tif­ic prog­ress. This work should help to re­di­rect sci­en­tif­ic ef­forts to­ward those pro­cesses that really do con­trol age­ing.”

Re­search­ers at the Uni­vers­ity of Wash­ing­ton, Se­at­tle, and Sem­mel­weis Uni­vers­ity, Bu­da­pest, ex­am­ined two strains of nem­a­tode worm, each from a dif­fer­ent pri­or stu­dy. These were ma­ni­pu­lated to have a hy­per­ac­tive sir­tuin gene to that the hypothesis might be tested. The nematode indeed was initially found to live longer, but subsequent tests showed that after living conditions were made the same for both normal and genetically-enhanced worms, that there wasn’t any considerable difference in lifespan which could’ve been attributed to sirtuin. Suspecting that some other genetic factor must have caused the longevity, they identified a mutation in a gene involved in the development of nerve cells as the cause.

In the case of the fruit-fly, were considerable longevity was also reported, scientists actually engineered a new strain of fruit fly, Dro­soph­i­la melanogaster, which could hyper-actively generate sirtuin. They found no reason to consider the new strain particularly long-lived.

Finally, the dietary restriction was also put to the test. ak­ing mu­tant fruit flies that lacked the sir­tuin gene, the re­search­ers showed that di­e­tary re­stric­tion still in­creased life­span. So di­e­tary re­stric­tion was work­ing in­de­pend­ently of sir­tu­ins.

All those sirtuin-based creams and pills are nothing but expensive placebos.