Ageing: It’s All in Your Head

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How low-calorie diets can give you a longer life

By most accounts, the first person to extol the benefits of a controlled diet as a means to achieving better health and longevity was a Japanese philosopher and scientist named Ekiken Kaibara in the 18th century. Over the years, a number of studies have found a link between a low-calorie diet and longer life spans. However, nobody has been able to prove why such a link exists.

A new study claims to have found the answer. According to it, lowcalorie diets enhance the presence of a specific type of sirtuin protein in the brain called SIRT1, which enhances the production of a specific neural receptor in the brain involved in regulating metabolic rate, food intake and insulin sensitivity.

The study, which was conducted on mice that had been genetically modified to produce more SIRT1, found that an enhanced SIRT1 was able to extend the median life span of the mice by 16 per cent for females and 9 per cent for males. This, when translated to human years, could mean an extended 13 or 14 years for women, making their average life span almost 100 years, and another seven years for men, increasing their average life span to the mid-80s.

The study, conducted by researchers from Washington University School of Medicine in St. Louis, was published in Cell Metabolism. The mice under study were genetically modified to overproduce SIRT1 protein. Some mice were engineered to overproduce SIRT1 in body tissues, while others only in the brain. They found that only mice that had enhanced presence of SIRT1 in the brain had significant longer life spans, similar to those reared under dietaryrestriction regimens. Also, the skeletal muscular structures of old mice with a high presence of SIRT1 resembled young muscle tissue. For instance, according to the researcher, 20-month-old mice looked as active as five-month-olds.

They also observed significant increases in body temperature, oxygen consumption and physical activity during the night compared with agematched controls. Delay in cancerrelated deaths was also found.

According to the researchers, their discovery of a close link between SIRT1 and longevity raises the likelihood of a control centre in the brain that controls ageing and longevity. Such a presence could mean that in future scientists can try to manipulate it to extend life spans of other animals, including humans.