By Jim English Caloric restriction has been shown to be one of the most effective means of slowing the pace of aging and extending lifespan. Studies show that severely reducing the food intake of laboratory mice can increase their lifespan to the human equivalent of 162 years. Other experiments demonstrate similar gains in maximum lifespan with fruit flies and worms. Yet despite the potential increase in lifespan observed with caloric restriction, few humans would willingly choose to live in a constant state of semi-starvation for even a few days, let alone 162 years. Activate your 'skinny gene' with the sirt food diet and not only will you lose weight. They activate fat. Which are responsible for switching on sirtuin genes. A new study demonstrates what researchers consider conclusive evidence that the red wine compound resveratrol directly activates a protein that promotes health. For the last decade, the science of aging has increasingly focused on sirtuins, a group of genes that are believed to protect many organisms,. Sirtuin 1, also known as NAD-dependent deacetylase sirtuin-1, is a protein that in humans is encoded by the SIRT1 gene. SIRT1 stands for sirtuin (silent mating type information regulation 2 homolog) 1 (S. Cerevisiae), referring to the fact that its sirtuin homolog (biological equivalent across species) in yeast (S. Cerevisiae) is Sir2. Researchers from Harvard Medical School just announced that resveratrol, a polyphenolic compound found in red wine, duplicates the life-extending benefits of caloric restriction in a yeast model. In a paper published in the August 24 online edition of the journal, Nature, they report that resveratrol was shown to extend the lifespan of yeast by up to 80 percent. SIR-2 – The Longevity Enzyme Researchers have known for decades that reducing daily intake of calories by up to 40 percent dramatically slows down the aging process and extends lifespan of lab animals. Caloric restriction also has been shown to protect mammals from cancer and other age-related diseases. Recently scientists identified a class of regulatory “longevity genes” that are shared by almost all living organisms. These genes function as a feedback system to enhance survival during times of stress, such as during drought or famine. The process begins when external signals indicate a deterioration of environmental conditions. Once triggered by environmental cues, the longevity genes “switch on” and induce defensive changes at the cellular level, such as slowing metabolism and enhancing cellular respiration to help the body adapt to a more beneficial survival program. In their study, the Harvard researchers focused on a family of enzymes, called sirtuins, produced by almost all life forms – from single celled organisms, to plants and mammals – during times of stress, such as famine (or caloric restriction). Sirtuins (silent information regulator proteins) are known to act as guardian enzymes that protect cells and enhance cellular survival. The human sirtuin, SIRT-1, for example, has been shown to suppress the p53 enzyme system normally involved in suppressing tumor growth and instigating cell death (apoptosis). By suppressing p53 activity SIRT-1 prevents the cycle of premature aging and apoptosis normally induced when cellular DNA is damaged or stressed, thus giving cells enough time to repair any damage and prevent unnecessary cell death. A second sirtuin found in yeast, SIR2, has also been shown to become activated when placed under stress. SIR2 has been shown to increase DNA stability and speed cellular repairs, while increasing total cell lifespan. “We think sirtuins buy cells time to repair damage,” said molecular biologist David Sinclair, assistant professor of pathology at Harvard Medical School and co-author of the new study. “There is a growing realization from the aging field that blocking cell death – as long as it doesn’t lead to cancer – extends lifespan.” An Alternative to Caloric Restriction Intrigued by the positive health benefits of caloric restriction, the Harvard research team began to search for other methods of modulating sirtuin activity without resorting to starvation. After an initial screening process, the researchers discovered that several plant metabolites acted as sirtuin-activating compounds (STACs). Plants produce a variety of polyphenols, such as resveratrol, flavones, stilbenes, isoflavones, catechins and tannins in response to environmental stresses, such as drought, nutrient depleted soils, ultraviolet radiation and pathogens. As they refined their screening process the researchers discovered that the most potent activator of sirtuins was resveratrol. To test the ability of resveratrol to activate sirtuins in living creatures the Harvard researchers selected yeast, a single-celled organism that is closely related to animals, including humans.
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April 2018
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