There has been major research done in animals that suggests how having a strict diet that limits the consumption of particular nutrients can increase one’s lifespan and lessen the incidence of certain age-related diseases. It might even be possible to use drugs to reproduce these same effects, it would seem. Yet as of today, there are still no clinically proven anti-aging diets, nor drugs, as scientists have yet to figure out their safety.
Regardless, diets that claim that they help slow down the aging process have become incredibly popular over the past few years. In fact, they even share their evidence on how participating in nutrient-restricting diets could even increase a healthy lifespan, as seen in laboratory organisms like worms, flies, yeast, and rodents.
Back in 1917, Science journal published the first study that showed evidence that restricting calories in rats can delay their development while dramatically increasing their lifespan.
Since then, a hundred years have since passed, and once again the Science journal published a roundup of a number of different research papers that have been written until today that talk about the safety and the effectiveness of these diets that claim to slow down the process of aging.
A group of scientists at the University of Washington in Seattle and Pennington Biomedical Research Center in Baton Rouge, CA, decided to make a review of these popular anti-aging diets. Aside from the caloric restriction diets, they also included diets that rigidly limit a person’s intake of proteins, carbohydrates, and certain amino acids.
The research group also looked at evidence of the different fasting regimes, focusing on their efficacy. Incredibly, most of these well-known diets reportedly have good effects on aging and health ‘through their influence on a single metabolic pathway that yeast, worms, rodents, and humans have in common.’
According to the research group, in theory, there are already drugs in existence that could possibly reproduce the diets’ beneficial effects without the need for the individual to go hungry or even have to give up certain kinds of food.
Although the authors of this new study are highly optimistic about the future of such anti-aging diets, they also warn that they might not work equally well for all of those using them.
Some people that have a particular genetic makeup, or possibly one that is dealing with environmental conditions, when they follow these diets, it could be even worse for them and their health.
This is also why the reviewers emphasize how there are yet to be clinically proven anti-aging diets and that more research is needed so that the doctors can provide a diet for those considered to be healthy people.
Caloric Restriction Diet
When testing out a caloric restriction diet on mice and rats, while still giving them all the essential nutrients they require, the animals were healthier with an average lifespan that increased as compared to the animals that were fed just ordinary lab diets.
Moreover, the same rodents had a reduced incidence of age-related diseases, such as cardiovascular disease, type 2 diabetes, cancer, and neurodegenerative disorders.
There is also a very contrary relationship between calorie intake – or at least 50% calorie restriction – and the lifespan of animals. Those that started the diets when they were younger seemed to have the most benefits. Yet, while the results found from research done in lab animals is pretty clear cut, the authors also explain that they can’t say the same yet for humans.
The study authors explain that their research also used house mice and rats, keeping them in a pathogen-free condition while keeping a close look out for their health. On the other hand, if this was to be attempted on humans, there are too many factors for humans to consider such as their environments and lifestyles, which tend to have a ‘huge impact on the health effects of potential life-extending diets.’ In addition, genetic variations between the different individuals will most probably play a large role in the outcome of the diet.
Plus, mice have incredibly different metabolic demands as compared to human, considering how much smaller they are as well. The authors also explain that in order to maintain their core body temperature, they have to find a way to burn at least half of the calories they eat every day.
Another problem with the study is the fact that mice only live a few years as compared to their human counterparts, which can span decades. This means doing comparable studies in humans could take major years to finish.
Some Risks and Benefits
When it comes to extreme calorie restriction, which is where the research claims it will probably get the best life extension, it could also come with a major cost. Research shows that a relatively small number of people can even remain on the highly restrictive diet, but it also comes with a cost.
For some that have managed to do the restrictive diet, there are possible side effects, such as chronic fatigue, poor sleep, muscle weakness, loss of libido, poor cold tolerance, impaired wound health, psychological problems, impaired wound healing, and increased possibility of infection.
The authors said, “[S]evere [calorie restriction] can impair both immune function and wound healing, which could offset any potential lifespan-extending benefits under adverse environmental conditions in which the immune system is challenged, for example, a global viral pandemic, or in the absence of quality healthcare.”
However, there is also some other observational evidence that found how less extreme calorie restriction can produce significant benefits. One example is the inhabitants of a tiny Japanese island in Okinawa where they people traditionally take in 20% fewer calories than anyone who lives on the mainland.
In fact, the past has seen quite the number of Okinawa residents that have had the longest life expectancy, while also having the highest number of centenarians ‘per head of population anywhere in the world.’
Research also suggests that they have exceptionally low age-related illnesses rates, which includes cardiovascular disease, diabetes, and cancer. Yet, just like with any other observational studies, the research doesn’t establish if it’s the calorie restriction that’s responsible for these positive health benefits.
There are have been clinical trials yet to test if there is an increased overall lifespan when practicing calorie restrictions, there has been a series of shorter trials that lasted from a few month to up to two years which found how clinical benefits that show there is a likelihood for an extended healthy lifespan.
The study findings show that ‘a 25% reduction in calorie intake is associated not only with decreased weight but also enhanced insulin sensitivity and glucose tolerance and improvements in risk factors for cardiometabolic disease.’
Let’s Talk Ketogenic Diets
One popular “anti-aging” diet is the Ketogenic diet. It is a diet that strictly limits the consumption of carbohydrates and sugar, but allows the unrestricted intake of healthy fat, which forces the body to use its ketone molecules to fuel the body, which are a byproduct of the fat metabolism in the liver.
With this type of diet, it has also been seen to lessen the frequency of seizures in people that have epilepsy, while promoting weight loss in those that are overweight or obese.
Back in 2017, two studies were done that reported how a low carbohydrate and low protein ketogenic diet managed to increase the average lifespan of mice while improving their health in their ‘old’ age.
For one of the studies, it was found that the keto diet lessened their mortality in midlife while improving their memory as they aged. Meanwhile, the other study found that their longevity was increased, as well as a health lifespan.
The review authors share that although the diet seems effective, the long-term effects of these types of diets have yet to be determined. But they also share that the animal findings remain “highly suggestive” that ketones could really have anti-aging properties.
Let’s Talk Fasting
While there are a number of variations when it comes to the fasting diet trend, the basically fall into these three broad categories:
1. Intermittent Fasting – this involves consuming very few to no calories during ceratin time frames within the day, between 1 to 4 times a week.
- Fasting-Mimicking Diets – this is when you induce the same metabolic changes when doing a low calorie, low protein diet around 5 days within the month.
- Time-Restricted Fasting – this diet involves restricting eating to a particular number of hours every day.
The review authors explain that most of the preclinical animal studies done with these diets are effectively investigating these different types of calorie restriction. They share that this is due to the animals in the experimental group tend to consume less calories than those in the control group. In the end, it’s hard to distinguish the potential benefits of fasting from the other well-established benefits found in calorie restriction.
But again, the review authors also point out another study done in mice that only allowed them to eat on alternating days with mice that ate the same overall calories except without fasting. What they found were improvements in the metabolism alongside reduced inflammation in the group of mice that did forced intermittent fasting.
Yet, an equivalent study in humans found that those who were made to fast every other day had less benefits to their health than those that were made to simply eat a calorie-restricted diet with the same overall energy intake. Again, the results for the time-restricted fasting diet from the animal and human studies are equivalently conflicting.
The review authors explain that the studies in mice found ‘time-restricted fasting improved various measures of metabolic health and protected against an obesogenic or obesity-causing diet.’ Yet studies in humans have received very mixed results for time-restricted fasting diets. While some studies show only mild health improvements, others have suggested that there are more adverse effects on one’s glucose metabolism.
Let’s Talk Protein and Amino Acid Restriction
The authors of the review also note that there are a lot of studies that find restricting protein intake could increase the lifespan of rodents while reducing age-related diseases as well. They share that although protein restriction in itself can increase lifespan, the benefits can be considerably less than those obtained from calorie restriction.
Moreover, the review authors also share that there is evidence that restricting dietary intake of certain essential amino acids, which the body is incapable of synthesizing on its own, can also extend one’s lifespan. Animal studies also suggest that by restricting methionine, valine, tryptophan, isoleucine, and leucine could be beneficial to increasing a healthier lifespan.
The Universal Aging Switch
Notably, nutrient-restricting diets do show that they can increase longevity while reducing age-related diseases through ‘their positive effect on a small number of metabolic pathways.’ This specifically speaks of the diets that tend to lessen levels of ‘growth hormone, insulin-like growth factor, and a signaling molecule called mechanistic target of rapamycin (mTOR).’
There has been research done in nematode worms and yeast that shows how these molecules are ‘key hubs in a molecular mechanism that senses the availability of nutrients in the animals’ environment.’
This mechanisms’ job is to promote the cellular maintenance and repair when nutrients are deficient but manage to still redeploy the organism’s resources to reproduction when the nutrients are sufficient.
As with the disposable soma theory, this mechanism shows the trade-off that all organisms, from yeast all the way to people, have to do in order to stay alive and reproduce.
Let’s Talk Anti-Aging Drugs
With the existence of a nutrient-sensing mechanism that has the ability to control aging also raises the potential possibility of targeting it with a drug that can promote longer, healthier lives. While there are such drugs that do exist, the review authors also say that of all, the most promising is rapamycin, a drug that can reduce the activity of mTOR while promoting healthier aging in rats.
What remains to be seen is whether the drug can combat aging at the same extent in human beings, since they usually have relatively long lifespans already.
Prof. Matt Kaeberlein, Ph.D., who studies aging in lab animals and pet dogs at the University of Washington, also happens to be a corresponding author of the review. He told Medical News Today (MNT) that he is optimistic about these meds.
He said, “It’s early, but there are hints that it’s possible to tweak the network with rapamycin in older dogs and people to potentially achieve similar functional benefits in the heart and immune system as what is seen in mice.”
“Whether that will translate through to health span more broadly or lifespan or not, we don’t know yet, but I think we will get that answer in the next 5-10 years,” he added.
But the review authors also note that there are a number of questions that remain about the potential side effects of this medication as well. Oftentimes, doctor give high doses of the drug to modulate the immune system and to prevent rejection of organs in organ transplant patients.
They also explain that at these particular doses of the rapamycin, the side effects could be severe, although its proponents as an anti-aging drug also claim that their benefits outweigh the cost when given at lower doses.
Talking Treatment for Diseases of Aging
Director of the Oklahoma Nathan Shock Center on Aging in Oklahoma, OK, Arlan Richardson, Ph.D. recently co-authored an article that was published in the GeroScience journal which talks about rapamycin and aging.
The article cites that research should look at the drug as a potential treatment for diseases of aging like Alzheimer’s disease. He explained to MNT that there is another paper done by his research group that suggests that combining calorie restriction and rapamycin could possibly provide even ore benefits for older people that either one done alone.
Although the effects of the drug and the diet overlap each other, each one also influences a range of different pathways. He said, “While [calorie restriction] inhibits mTOR, it has more effects, as we have reported.”
In the end, the review authors conclude that “[f]uture research should focus both on better understanding the cellular and molecular mediators of anti-aging diets under highly controlled laboratory conditions as well as the impact of genetic and environmental variation on health outcomes associated with these diets.”
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