Thursday, March 29, 2007

Calorie restriction and mitochondrial function

does calorie restriction extend lifespan in humans? we don't know for sure yet, but it looks like it might increase mitochondrial function in muscle (over 6 months).

Calorie Restriction Increases Muscle Mitochondrial Biogenesis in Healthy Humans

Anthony E. Civitarese*, Stacy Carling, Leonie K. Heilbronn, Mathew H. Hulver, Barbara Ukropcova, Walter A. Deutsch, Steven R. Smith, Eric Ravussin for the CALERIE Pennington Team

PLoS Med 4(3): e76

Background Caloric restriction without malnutrition extends life span in a range of organisms including insects and mammals and lowers free radical production by the mitochondria. However, the mechanism responsible for this adaptation are poorly understood.

Methods and Findings The current study was undertaken to examine muscle mitochondrial bioenergetics in response to caloric restriction alone or in combination with exercise in 36 young (36.8 ± 1.0 y), overweight (body mass index, 27.8 ± 0.7 kg/m2) individuals randomized into one of three groups for a 6-mo intervention: Control, 100% of energy requirements; CR, 25% caloric restriction; and CREX, caloric restriction with exercise (CREX), 12.5% CR + 12.5% increased energy expenditure (EE). In the controls, 24-h EE was unchanged, but in CR and CREX it was significantly reduced from baseline even after adjustment for the loss of metabolic mass (CR, −135 ± 42 kcal/d, p = 0.002 and CREX, −117 ± 52 kcal/d, p = 0.008). Participants in the CR and CREX groups had increased expression of genes encoding proteins involved in mitochondrial function such as PPARGC1A, TFAM, eNOS, SIRT1, and PARL (all, p < p =" 0.005)" p =" 0.003)" p =" 0.011)," style="font-weight: bold;">
Conclusions The observed increase in muscle mitochondrial DNA in association with a decrease in whole body oxygen consumption and DNA damage suggests that caloric restriction improves mitochondrial function in young non-obese adults.

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