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Caloric Restriction: Difference between revisions
→Effects in Different Organisms
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==Effects in Different Organisms== | ==Effects in Different Organisms== | ||
=== Positive Effects === | |||
[[File:Caloric restriction 02.png|thumb|Effects of calorie restriction on the survival rate of laboratory mice (CR=Calorie Restriction).{{pmid|3958810}}]] | [[File:Caloric restriction 02.png|thumb|Effects of calorie restriction on the survival rate of laboratory mice (CR=Calorie Restriction).{{pmid|3958810}}]] | ||
[[File:Drosophila melanogaster - side (aka).jpg|thumb|Calorie restriction can significantly increase the lifespan of the fruit fly (''Drosophila melanogaster'').]] | [[File:Drosophila melanogaster - side (aka).jpg|thumb|Calorie restriction can significantly increase the lifespan of the fruit fly (''Drosophila melanogaster'').]] | ||
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In many species, not only is the average lifespan of the test animals increased, but also their maximum lifespan. The frequency of age-related diseases correspondingly decreases.{{pmid|18729811}} The effect of an increase in maximum life expectancy occurs in rodents both when starting the diet in the early life phase (1st to 3rd month), and in the middle life phase (12th month).{{pmid|12424798}}{{pmid|10630588}} However, if calorie restriction is started in a later life phase of the test animals, such as in the 17th or 24th month of mice, the effect reverses and the lifespan of the test animals is shortened.{{pmid|12586746}} | In many species, not only is the average lifespan of the test animals increased, but also their maximum lifespan. The frequency of age-related diseases correspondingly decreases.{{pmid|18729811}} The effect of an increase in maximum life expectancy occurs in rodents both when starting the diet in the early life phase (1st to 3rd month), and in the middle life phase (12th month).{{pmid|12424798}}{{pmid|10630588}} However, if calorie restriction is started in a later life phase of the test animals, such as in the 17th or 24th month of mice, the effect reverses and the lifespan of the test animals is shortened.{{pmid|12586746}} | ||
Both in a study with rhesus monkeys{{pmid|22932268}} by the American | Both in a study with rhesus monkeys{{pmid|22932268}} by the American National Institute on Aging, and in a study on ''Drosophila''{{pmid|16000018}}, it has been suggested that life extension depends not only on calorie restriction but also on the composition of the diet. | ||
===General Criticism=== | |||
Various findings raise doubts about the notion that caloric restriction slows down the aging process, delays the age-related decline in physiological fitness, or extends the lifespan of organisms from different phylogenetic groups.{{pmid|24941891}} Positive effects of caloric restriction are not universal: | |||
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.<ref>C. Y. Liao, B. A. Rikke, T. E. Johnson, V. Diaz, J. F. Nelson: ''Genetic variation in the murine lifespan response to dietary restriction: from life extension to life shortening.'' In: ''Aging Cell.'' Volume 9, Number 1, February 2010, {{ISSN|1474-9726}}, pp. 92–95, [[doi:10.1111/j.1474-9726.2009.00533.x]], PMID 19878144, {{PMC|3476836}}.</ref><ref>B. A. Rikke, C. Y. Liao, M. B. McQueen, J. F. Nelson, T. E. Johnson: ''Genetic dissection of dietary restriction in mice supports the metabolic efficiency model of life extension.'' In: ''Experimental Gerontology.'' Volume 45, Number 9, September 2010, {{ISSN|1873-6815}}, pp. 691–701, [[doi:10.1016/j.exger.2010.04.008]], PMID 20452416, {{PMC|2926251}}.</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> | |||
The aforementioned NIA study on rhesus monkeys found no lifespan extension.{{pmid|22932268}} In a long-term study conducted at the ''Wisconsin National Primate Research Center'' over a period of 20 years on rhesus monkeys, a significantly better health status and a significantly increased lifespan were observed in the group of animals that received a reduced food supply during this period. In this | |||
==Benefits of Caloric Restriction== | ==Benefits of Caloric Restriction== | ||
Research suggests that caloric restriction may offer several health benefits, including: | Research suggests that caloric restriction may offer several health benefits, including: | ||