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Caloric Restriction: Difference between revisions
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In fruit flies, positive effects of caloric restriction are not reproduced with careful control of nutrient fractions.{{pmid|18268352}} | In fruit flies, positive effects of caloric restriction are not reproduced with careful control of nutrient fractions.{{pmid|18268352}} | ||
The increase in lifespan caused by caloric restriction is not even reproducible among different strains of the same species.{{pmid|24941891}}[[File:Caloric restriction with different mice.png|thumb|Calorie restriction does not extend lifespan in all mice. In the top graph, a significant effect is observed in C57BL/6 mice ("laboratory mice"), while it is absent in DBA/2 mice ("wild type") below (AL=''ad libitum'', CR=Calorie Restriction).{{pmid|12586746}}]]Thus, calorie restriction does not lead to lifespan extension in all mouse strains.{{pmid|12586746}} In 19 to 27% of the mouse strains studied, a 40% caloric restriction even resulted in a shortened lifespan. | The increase in lifespan caused by caloric restriction is not even reproducible among different strains of the same species.{{pmid|24941891}}[[File:Caloric restriction with different mice.png|thumb|Calorie restriction does not extend lifespan in all mice. In the top graph, a significant effect is observed in C57BL/6 mice ("laboratory mice"), while it is absent in DBA/2 mice ("wild type") below (AL=''ad libitum'', CR=Calorie Restriction).{{pmid|12586746}}]]Thus, calorie restriction does not lead to lifespan extension in all mouse strains.{{pmid|12586746}} In 19 to 27% of the mouse strains studied, a 40% caloric restriction even resulted in a shortened lifespan.{{pmid|19878144}}{{pmid|20452416}} | ||
The frequently used [[C57BL/6 mice|C57BL/6]] mice tend to become overweight with unrestricted food access (''ad libitum''). In these animals, the effect of caloric restriction is significant. DBA/2 mice, on the other hand, remain lean even with ad-libitum feeding. In mice from this strain, caloric restriction does not lead to lifespan extension. DBA/2 mice consume more oxygen with the same energy intake than C57BL/6 mice, meaning their metabolic rate is increased – they are poorer "feed converters."{{pmid|19141702}} It was already observed in earlier experiments that caloric restriction is most successful in mice that gain significant weight in early adulthood.{{pmid|958413}} The results of these studies are interpreted to mean that lifespan is more influenced by the balance of energy intake and energy expenditure. Only in test animals prone to overweight or obesity can caloric restriction cause lifespan extension.<ref>{{Cite web|url=https://www.aerzteblatt.de/nachrichten/35192/Lebensverlaengerung-Mythos-der-Kalorienrestriktion-widerlegt|title=Life Extension: Myth of Caloric Restriction Refuted|website=[[Deutsches Ärzteblatt|aerzteblatt.de]]|date=2009-01-26|archive-url=https://web.archive.org/web/20150518230228/http://www.aerzteblatt.de/nachrichten/35192/Lebensverlaengerung-Mythos-der-Kalorienrestriktion-widerlegt|archive-date=2015-05-18|archive-bot=2019-09-14 14:53:42 InternetArchiveBot|access-date=2015-05-01}}</ref> | The frequently used [[C57BL/6 mice|C57BL/6]] mice tend to become overweight with unrestricted food access (''ad libitum''). In these animals, the effect of caloric restriction is significant. DBA/2 mice, on the other hand, remain lean even with ad-libitum feeding. In mice from this strain, caloric restriction does not lead to lifespan extension. DBA/2 mice consume more oxygen with the same energy intake than C57BL/6 mice, meaning their metabolic rate is increased – they are poorer "feed converters."{{pmid|19141702}} It was already observed in earlier experiments that caloric restriction is most successful in mice that gain significant weight in early adulthood.{{pmid|958413}} The results of these studies are interpreted to mean that lifespan is more influenced by the balance of energy intake and energy expenditure. Only in test animals prone to overweight or obesity can caloric restriction cause lifespan extension.<ref>{{Cite web|url=https://www.aerzteblatt.de/nachrichten/35192/Lebensverlaengerung-Mythos-der-Kalorienrestriktion-widerlegt|title=Life Extension: Myth of Caloric Restriction Refuted|website=[[Deutsches Ärzteblatt|aerzteblatt.de]]|date=2009-01-26|archive-url=https://web.archive.org/web/20150518230228/http://www.aerzteblatt.de/nachrichten/35192/Lebensverlaengerung-Mythos-der-Kalorienrestriktion-widerlegt|archive-date=2015-05-18|archive-bot=2019-09-14 14:53:42 InternetArchiveBot|access-date=2015-05-01}}</ref> | ||