Calories Do Not Explain Extension of Life Span by Dietary Restriction in Drosophila

William Mair,Matthew D W Piper,Linda Partridge,Thomas Kirkwood

doi:10.1371/journal.pbio.0030223

William Mair, Matthew D W Piper + Show 2 more

Open Access

https://doi.org/10.1371/journal.pbio.0030223

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Journal: PLoS Biology	Publication Date: May 31, 2005
Citations: 520	License type: CC BY 4.0

Affiliation: University College London

Abstract

Dietary restriction (DR) extends life span in diverse organisms, including mammals, and common mechanisms may be at work. DR is often known as calorie restriction, because it has been suggested that reduction of calories, rather than of particular nutrients in the diet, mediates extension of life span in rodents. We here demonstrate that extension of life span by DR in Drosophila is not attributable to the reduction in calorie intake. Reduction of either dietary yeast or sugar can reduce mortality and extend life span, but by an amount that is unrelated to the calorie content of the food, and with yeast having a much greater effect per calorie than does sugar. Calorie intake is therefore not the key factor in the reduction of mortality rate by DR in this species.

Highlights

Dietary restriction (DR), the extension of life span by reduction of nutrient intake without malnutrition, is often used as a benchmark comparison for interventions that extend life span [1,2,3]
DR can be applied in Drosophila by the simultaneous dilution of the nutrients in a standard sugar yeast (SY) food medium [9] in which the yeast is the only source of protein and lipid
The response of Drosophila life span to nutrition is not governed by calories, but rather by specific nutritional components of the food

Summary

Introduction

Dietary restriction (DR), the extension of life span by reduction of nutrient intake without malnutrition, is often used as a benchmark comparison for interventions that extend life span [1,2,3]. DR is often termed ‘calorie restriction’ because, in rodents, daily calorie intake per se has been implicated as the key determinant of life span, with the source of these calories (i.e., carbohydrate, protein, or fat) being considered irrelevant [1]. Evidence for this point of view came from two types of experiment on rats: (1) restriction of calorie intake without reduction of protein intake resulted in life-span extension [15]; (2) no life-span extension was seen in rats fed isocaloric diets in which either the fat or mineral components had been reduced [16]. Personal communication) and rats [20] It seems that reducing the level of ingested calories may not always be critical for life-span extension by DR in rodents.

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