Tuesday, December 8, 2009

George Roth: "Caloric restriction increases life expectancy"

Dr. George Roth has long headed the department of molecular physiology and genetics of the prestigious National Institute of Aging USA (NIA, Baltimore, Maryland). It is considered one of the best specialists in the biology of aging. For him the caloric restriction is an effective way to increase life expectancy.

George, you're officially over in academic research, but you continue to publish studies with your former colleagues at the National Institute of Aging in Baltimore.
George Roth: Yes, I've been in the private sector, I created a small structure research Gerosciences but I remain emotionally attached to my old unit and research in which I participated.

There are currently three cohorts of rhesus monkeys in caloric restriction. What is their state of health compared to monkeys that were fed normally?
Indeed, in addition to the monkeys that we follow the NIA, there are those of the University of Wisconsin and those of the University of Maryland. To speak only of our own mortality in the caloric restriction group is lower than it is in the group of monkeys fed normally but the difference was not statistically significant. It is likely that combining our results with those of other cohorts, we obtained a significant difference. Regarding morbidity, that is to say the incidence of diseases related to age, caloric restriction in monkeys are better. For example, they have less cancer and these appear later. So, overall, what we see on monkeys reflects the hypothesis that caloric restriction increases life expectancy.

Do we know better how eating less can live longer?
It should be noted that the experiences of caloric restriction are not malnutrition. There are fewer calories, but intake of vitamins and minerals are optimized. Now, regarding why calorie restriction is so effective to increase the maximum life expectancy of all living species in which she studied, there are several hypotheses. The most popular and also the oldest, is that if you absorb fewer calories, you reduce the level of oxidative stress is an important factor in aging. Many teams working on these mechanisms.

There are numerous markers of oxidative stress, we have reviewed on this site. Do we know who are affected by caloric restriction?
You're right to say that awash in markers of oxidative stress! Each year, we announced a new marker! Nevertheless, it seems that the isoprostane is a good candidate. The level of isoprostane is modulated by caloric restriction. In living, it increases with age. But calorie restriction, it is much slower.

Apart from reducing oxidative stress, how caloric restriction might extend her life?
There's this concept of hormesis that can be summarized as: stress, toxins that are potentially harmful to the body can lead to low dose biological response that has a beneficial effect. Caloric restriction may be related to stress. We know that calorie restriction increases the level of a family of proteins called heat shock proteins (in English or heat shock proteins HSP). HSPs are part of molecules called chaperones that associate with other molecules to protect them. The role of HSP is to prevent the accumulation of abnormal proteins in helping to structure properly. HSPs play an important role in preventing chronic and degenerative diseases like cancer.

Caloric restriction has also meant a drop in body temperature.
Yes, but this is not strong enough to explain alone the benefits of caloric restriction. Clearly it reflects the fact that the organization's resources are more growth-oriented, but the maintenance of vital functions. There is also another important element caused by caloric restriction: the decrease of IGF-1, a growth factor and increased sensitivity to insulin. My feeling is that these mechanisms are involved.

And now that the first human studies have begun, we will perhaps learn more.
There are now three controlled studies in humans. They are very encouraging. The results fit well into what is known about caloric restriction in animals. In humans also eat less when body temperature decreases and insulin levels as well.

A few years ago, Don Ingram and now you are interested in biomarkers of aging, "which would, in short, biological analysis to predict the rate of aging. Where are we?
While the field of biomarkers of aging has been controversial since its inception. It is extremely difficult to find biomarkers that are affected by the passage of time and not something else, a disease for example. None of the biomarkers that we published is really confirmed by other researchers, although some are associated with age, simply because our attempts have been fairly rudimentary. Don is not able to take a "snapshot organic" an individual and say "that is his age." DHEA change much with age, but also by changing times, there is great variability. So in this area, nothing is final, it must continue to dig.

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