|Life Extension Update Exclusive |
Calorie quality more important than quantity?
The results of a study published in volume 3, issue 7 of PLoS (Public Library of Science) Biology indicated that reductions in the type of calories consumed might be more important than amount in extending life span. Although the finding was observed in fruit flies and may not necessarily hold true for higher species, it could be an indication that there are other ways of restricting the diet to extend lifespan that do not involve severe calorie restriction.
Researchers at the Centre for Research on Ageing at University College in London gave fruit flies a standard diet consisting of yeast and sugar in water, or diets modified to restrict yeast (which provides protein and fat) or sugar, (which provides carbohydrates), both which contain the same amount of calories per gram. An additional group received diets in which both components were restricted.
Reduction of both dietary components, which resulted in the fewest calories consumed, extended the flies’ lives to the greatest extent compared with those on normal diets. In flies that received diets in which either the amount of yeast or sugar was lowered but contained the same number of calories, there was a significant difference in life span. Those whose diets contained lower amounts of yeast lived significantly longer than those whose sugar intake was restricted, and their life spans approached those of flies restricted in both yeast and sugar, whose calorie intake was the least. When flies on normal diets were switched at the age of 25 days to diets in which yeast was restricted, they were no more likely to die after 48 hours on the diet than those who were maintained on yeast restricted diets throughout adulthood. Flies fed non-restricted diets that were switched to sugar-restricted diets at 25 days died at the same rate as the non-restricted flies.
The authors suggest that yeast and sugar trigger different metabolic pathways with different effects on life span. They note that dietary yeast and egg production in fruit flies are correlated, and that increased reproduction has been demonstrated to reduce life span in a variety of species, however, although the response to dietary restriction in males is less than that of females, males still live longer in the regimen.
“Our results suggest that it may be possible to obtain the full extension of life span by dietary restriction by reducing critical nutrients in the food without any reduction in overall calorie intake,” they conclude.