Less Calories = Longer Life
Research into life extension and "curing" aging has become increasingly popular in recent years, with a better understanding of the biology of aging we are approaching the advent of treating aging like a disease rather than a part of life. Google has even began to dip its toes into the market with a sub corporation called "Calico". There are many molecular processes that are thought to be connected with life extension, some of the big ones being telomere function, autophagy, epigenetic modulation and the subject of this post, caloric restriction (CR) (3).
Now it may sound slightly absurd at first however in recent years it seems that this absurd notion may actually prove to be true. The first studies on the effects of food restriction (calorie restriction) were preformed by Clive McCay in 1935 on rats (4). These studies have been replicated in various degrees and with increasing regulations regarding animal health on mice, fruit flies, water fleas, spiders, fish, budding yeast and most recently rhesus monkeys (4). The results from these studies is overall there is an increase in the lifespan and decrease in the symptoms of aging. In a 1997 study on mice the CR group of mice lived an average of 40% longer than the group allowed to eat at their leisure. The most puzzling positive effects that CR has on rodents is that they have a " general up-regulation of mechanisms protecting against accumulation of somatic damage" (4). In more general terms, many processes that are related to somatic or cell damage caused by aging are decreased in the CR diet fed rodents. Processes like DNA repair activity, systolic antioxidant production, and expression of heat shock proteins remain at youthful levels longer (4). There are even more crazy findings in some of these articles, some showing evidence that rodents under CR diets don't show age related decline in would healing, and seems to eliminate the development of autoimmune diseases in susceptible strains of mice (4).
So, what about the rhesus monkeys, these are much closer to humans so if it can be shown that these creatures exhibit similar reactions to rodents, yeast and fish than they may also be applicable to humans. The study of calorie restriction and it's effects on rhesus monkeys started in 1989, with 30 males and was expanded in 1994 to include 30 females and 16 more males (2). The results of this study, which actually was only recently submitted in 2014, show that controlled animals had 2.9 times higher rate of age related death and 1.8 times higher rate of death by any cause (2). These numbers seem kind of small but have a little more impact when looking at percentages. Of the 78 original monkeys 63% of the control animals died of age related deaths while only 26% of the CR group did (2). This study was also beneficial for showing that the negative effects of CR are strain specific to the mice that showed negative effects, and with proper maintenance there were no negative effects on the monkeys in the study.
While testing this on humans may prove difficult there is actually a few cases where the effects of calorie restriction in humans has been observed. Part of the reason there is some data on calorie restriction in humans is that there is some passively observable data from third world and poor countries. These don't provide the best information since the calorie restriction is not regulated or even willing which causes other health problems and nutrient deficiencies. However, there is an exception to this pattern in the "Okinawan Centenarians". The people of Okinawa are subject to severe poverty and limited food, the food they do have access to however, is high in nutrients so there is actually a higher percentage of centenarians (people over 100 years old) in Okinawa than other parts of the world. The rub here is that the oldest people in Okinawa are no older than the oldest people in other parts of the world which contradicts some studies in rats where the CR rats are older than the oldest control rats (1).
There are so many more studies on this subject, the last one I will dip into is there is a group of people called the "Caloric Restriction Society" that believe so much in the benefits of CR that they willingly partake in calorie restricted diets. This is great for researchers and has given some very beneficial insight on the long term effects of CR in humans (1). The bare bones results on this one is that people on CR diets have low levels or chronic inflammation and lower cholesterol(1).
While there is still a lot of research to be done into this subject, it seems like a rather simple and tentatively promising method of life extension. The reasons for this adaptation are explored more in the article by B.L. Thomas, but there is not a clear answer. The key here is that calorie restriction does not mean stop eating or eating less. It is more a switch to "calorie- sparse, nutrient-dense foods" (5). The effects of this type of life extension seem to be the least invasive and are things the average human could feasibly do so it will be exciting to see the results of more long term human trials as well as continued animal research.
Note: The CR Society website looks kind of cultish but it is worth a look through.
1. Colman, R. J. et al. Caloric restriction reduces age-related and all-cause mortality in rhesus
monkeys. Nat. Commun. 5:3557 doi: 10.1038/ncomms4557 (2014).
2. Gasser, S. and J. Coutre. "Nutrition and the Biology of Human Ageing: Molecular Mechanisms Underlying Ageing." Journal of Nutrition, Health & Aging, vol. 17, no. 8, Aug. 2013, pp. 710-711. EBSCOhost, doi:10.1007/s12603-013-0373-4.
3. Holloszy, John O., and Luigi Fontana. “Caloric Restriction in Humans.” Experimental gerontology 42.8 (2007): 709–712. PMC. Web. 27 Oct. 2017.
4. Kirkwood, Thomas B.L. and Daryl P. Shanley. "Food Restriction, Evolution and Ageing." Mechanisms of Ageing and Development, vol. 126, no. Dietary restriction, longevity and ageing - the current state of our knowledge and ignorance, 01 Jan. 2005, pp. 1011-1016. EBSCOhost, doi:10.1016/j.mad.2005.03.021.
5.http://www.crsociety.org/resources/getting_started. Accessed 26, Oct, 2017
Now it may sound slightly absurd at first however in recent years it seems that this absurd notion may actually prove to be true. The first studies on the effects of food restriction (calorie restriction) were preformed by Clive McCay in 1935 on rats (4). These studies have been replicated in various degrees and with increasing regulations regarding animal health on mice, fruit flies, water fleas, spiders, fish, budding yeast and most recently rhesus monkeys (4). The results from these studies is overall there is an increase in the lifespan and decrease in the symptoms of aging. In a 1997 study on mice the CR group of mice lived an average of 40% longer than the group allowed to eat at their leisure. The most puzzling positive effects that CR has on rodents is that they have a " general up-regulation of mechanisms protecting against accumulation of somatic damage" (4). In more general terms, many processes that are related to somatic or cell damage caused by aging are decreased in the CR diet fed rodents. Processes like DNA repair activity, systolic antioxidant production, and expression of heat shock proteins remain at youthful levels longer (4). There are even more crazy findings in some of these articles, some showing evidence that rodents under CR diets don't show age related decline in would healing, and seems to eliminate the development of autoimmune diseases in susceptible strains of mice (4).
So, what about the rhesus monkeys, these are much closer to humans so if it can be shown that these creatures exhibit similar reactions to rodents, yeast and fish than they may also be applicable to humans. The study of calorie restriction and it's effects on rhesus monkeys started in 1989, with 30 males and was expanded in 1994 to include 30 females and 16 more males (2). The results of this study, which actually was only recently submitted in 2014, show that controlled animals had 2.9 times higher rate of age related death and 1.8 times higher rate of death by any cause (2). These numbers seem kind of small but have a little more impact when looking at percentages. Of the 78 original monkeys 63% of the control animals died of age related deaths while only 26% of the CR group did (2). This study was also beneficial for showing that the negative effects of CR are strain specific to the mice that showed negative effects, and with proper maintenance there were no negative effects on the monkeys in the study.
While testing this on humans may prove difficult there is actually a few cases where the effects of calorie restriction in humans has been observed. Part of the reason there is some data on calorie restriction in humans is that there is some passively observable data from third world and poor countries. These don't provide the best information since the calorie restriction is not regulated or even willing which causes other health problems and nutrient deficiencies. However, there is an exception to this pattern in the "Okinawan Centenarians". The people of Okinawa are subject to severe poverty and limited food, the food they do have access to however, is high in nutrients so there is actually a higher percentage of centenarians (people over 100 years old) in Okinawa than other parts of the world. The rub here is that the oldest people in Okinawa are no older than the oldest people in other parts of the world which contradicts some studies in rats where the CR rats are older than the oldest control rats (1).
There are so many more studies on this subject, the last one I will dip into is there is a group of people called the "Caloric Restriction Society" that believe so much in the benefits of CR that they willingly partake in calorie restricted diets. This is great for researchers and has given some very beneficial insight on the long term effects of CR in humans (1). The bare bones results on this one is that people on CR diets have low levels or chronic inflammation and lower cholesterol(1).
While there is still a lot of research to be done into this subject, it seems like a rather simple and tentatively promising method of life extension. The reasons for this adaptation are explored more in the article by B.L. Thomas, but there is not a clear answer. The key here is that calorie restriction does not mean stop eating or eating less. It is more a switch to "calorie- sparse, nutrient-dense foods" (5). The effects of this type of life extension seem to be the least invasive and are things the average human could feasibly do so it will be exciting to see the results of more long term human trials as well as continued animal research.
Note: The CR Society website looks kind of cultish but it is worth a look through.
1. Colman, R. J. et al. Caloric restriction reduces age-related and all-cause mortality in rhesus
monkeys. Nat. Commun. 5:3557 doi: 10.1038/ncomms4557 (2014).
2. Gasser, S. and J. Coutre. "Nutrition and the Biology of Human Ageing: Molecular Mechanisms Underlying Ageing." Journal of Nutrition, Health & Aging, vol. 17, no. 8, Aug. 2013, pp. 710-711. EBSCOhost, doi:10.1007/s12603-013-0373-4.
3. Holloszy, John O., and Luigi Fontana. “Caloric Restriction in Humans.” Experimental gerontology 42.8 (2007): 709–712. PMC. Web. 27 Oct. 2017.
4. Kirkwood, Thomas B.L. and Daryl P. Shanley. "Food Restriction, Evolution and Ageing." Mechanisms of Ageing and Development, vol. 126, no. Dietary restriction, longevity and ageing - the current state of our knowledge and ignorance, 01 Jan. 2005, pp. 1011-1016. EBSCOhost, doi:10.1016/j.mad.2005.03.021.
5.http://www.crsociety.org/resources/getting_started. Accessed 26, Oct, 2017
I knew there was research regarding life extension because everyone wants to live a longer life if they can. It's nice to know that nutrient dense foods, not only gives someone a healthier lifestyle, but it also can lead to a longer life. I always figured that to be true, but I had never read any research about it. I'm excited to see the long term effects of the calorie restriction in humans.
ReplyDeleteTerrific, multi-sourced, well-written. I used to know some of the calorie restrictors. Imagine Joe Pesci from the Snicker's commercial, but 24-7>
ReplyDeletehttps://www.youtube.com/watch?v=MixNh9L7G5M