14 DAY TRIAL // Bringing on food means a short happy life. But if you want to live longer, you must cut off from your daily food intake: look at those Okinawa people ... But why eating less prolongs life is still a question without any answer for the researchers.
Yet, a step closer towards solving the mystery could have been made by the discovery of a gene related to longevity in worms. Once solved the precise mechanism behind all this, future drugs could mimic the effects of calorie restriction without harsh fasting diets. The life-lengthening effects of low calories diets were first detected in the 1930s, when lab mice and rats fed with a poor calories diet lived much longer than their peers fed at their will. After that, the same effect was found on organisms as varied as yeast, flies, worms and dogs. There are human diets that drop by 60% the calories amount while keeping intact the nutrients values, but their effects are not very clear.
"If you reduce food too much, you go towards starvation and live less long. If you overeat you will succumb to obesity and have a short lifespan. Dietary restriction is really a sweet-spot between the two. But for 72 years, we have not known how it works." said co-author Andrew Dillin, an associate professor at the Salk Institute for Biological Studies. The research made on the nematode worm species Caenorhabditis elegans found the gene named pha-4 to be crucial for longevity: worms with this gene removed presented no higher longevity while on the restricted diet. When the gene was over-expressed, the worms displayed increased longevity when put on the restricted diet.
"This is the first gene we have found that is absolutely essential to the longevity response to dietary restriction. We finally have genetic evidence to unravel the underlying molecular program required for increased longevity in response to calorie restriction." said Dillin. "Mammals, including humans, possessed genes that were highly similar to the pha-4 gene," explained Dillin.
The pha-4 gene regulates the glucagon, a hormone implied in keeping steady levels of blood glucose, especially during fasting. "Pha-4 may be the primordial gene to help an animal overcome stressful conditions to live a long time through dietary restriction conditions (food scarcity)," explained Dillin.
The researchers plan to investigate for similar genes in other animals and people. "It is really hard to guess whether the connections that we see between the pha-4 system and calorie restriction in worms will have parallels in mammals, whose repertoire of responses to various forms of long- and short-term food shortages are far more complex than those of worms." said Professor Richard Miller of the Institute of Gerontology at the University of Michigan.