カロリー制限で筋肉量保持

カロリー制限で筋肉量を保持できるというアカゲザルでの動物実験を紹介します。
Susan H. McKiernan, et al: Cellular adaptation contributes to calorie restriction-induced preservation of skeletal muscle in aged rhesus monkeys. Experimental Gerontology, Available online 28 December 2011,

全文は見れませんが、抄録以外に図やハイライトを下記HPで見ることができます。
http://dx.doi.org/10.1016/j.exger.2011.12.009

抄録しか読んでいないのとこの領域は苦手なので詳細は不明ですが、アカゲザルのカロリー制限で16－22歳以降の筋肉量低下を遅らせることができることはすでに示されています。今回は最長17年間のカロリー制限で、27－33歳でも筋肉量低下を少なくできることが示されています。

サルコペニアの場合、飢餓による筋肉量低下の合併は避けなければいけません。一方、カロリー制限で自由摂取よりも筋肉量を保持できるという話もでています。サルコペニアで最適なエネルギー摂取量は一体どの程度なのでしょうか。悩ましいですね。蛋白に関しては高蛋白食のほうがよいと思いますが。

Abstract
We have previously shown that a 30% reduced calorie intake diet delayed the onset of muscle mass loss in adult monkeys between ~16 and ~22 years of age and prevented multiple cellular phenotypes of aging. In the present study we show the impact of long term (~17 years) calorie restricton (CR) on muscle aging in very old monkeys (27–33 yrs) compared to age-matched Control monkeys fed ad libitum, and describe these data in the context of the whole longitudinal study. Muscle mass was preserved in very old calorie restricted (CR) monkeys compared to age-matched Controls. Immunohistochemical analysis revealed an age-associated increase in the proportion of Type I fibers in the VL from Control animals that was prevented with CR. The cross sectional area (CSA) of Type II fibers was reduced in old CR animals compared to earlier time points (16–22 years of age); however, the total loss in CSA was only 15% in CR animals compared to 36% in old Controls at ~27 years of age. Atrophy was not detected in Type I fibers from either group. Notably, Type I fiber CSA was ~1.6 fold greater in VL from CR animals compared to Control animals at ~27 years of age. The frequency of VL muscle fibers with defects in mitochondrial electron transport system enzymes (ETSab), the absence of cytochrome c oxidase and hyper-reactive succinate dehydrogenase, were identical between Control and CR. We describe changes in ETSab fiber CSA and determined that CR fibers respond differently to the challenge of mitochondrial deficiency. Fiber counts of intact rectus femoris muscles revealed that muscle fiber density was preserved in old CR animals. We suggest that muscle fibers from CR animals are better poised to endure and adapt to changes in muscle mass than those of Control animals.