Calorie Restriction Increases Longevity – or Does It?
Here’s an interesting stat to bring up at the dinner table: For each human cell in your body, you have roughly ten non-human cells living in your gut. In other words, there are around 100 trillion microorganisms living in your intestines. But how does this mass of microorganisms affect our health and aging? US and Chinese researchers showed in Nature that these trillions of gut microorganisms are affected by the food we eat. In turn, this microbiota may play a role in our longevity.
In humans, microbiota of the gut is virtually non-existent at birth, but quickly increases with a diverse range of microorganisms. Thereafter, the gut microbiota is usually stable during the life course, but its composition can be affected by factors including illness and diet.
A decline in microbial diversity has been observed in the elderly, particularly in those consuming diets with little variety. Subsequently, these shifts in microbial populations may impact health, especially in the older population. Researchers observe that a reduction of some health-promoting microorganisms, and an increase of others, that may have adverse effects.
Experimental studies in animals and humans have confirmed that aging, medication and high-fat diets can lead to increased intestinal permeability. Consequently, this allows endogenous endotoxins (harmful molecules usually found within bacteria) to pass from the gut into the bloodstream. A prime example of these toxins are lipopolysaccharides.
Other factors can also influence blood lipopolysaccharide levels including infection, smoking and excessive consumption of alcohol. High-fat diets can also lead to increases in lipopolysaccharide levels. Therefore, researchers have proposed that this may be at least partly responsible for the chronic low-grade inflammation associated with diseases such as obesity, diabetes and heart disease.
Calorie restriction for longer life?
Calorie restriction has been studied for more than 70 years as a means to improve health and extend lifespans. However, the exact mechanisms of how restricting calories exerts these beneficial effects are not fully defined.
Most animal studies report that decreasing the caloric intake by 20% or more can prolong lifespan. Notably, the Nature study conducted on mice, reported that lifelong calorie restriction not only extends lifespan. Indeed, it also modifies the composition of the gut microbiota.
Male mice were fed a low-fat diet (10% fat) or a high-fat diet (60% fat). And within each of these two dietary groups, the animals were further divided into three groups:
- With voluntary wheel-running exercise
- Fed a 70% calorie-restricted diet
The researchers analyzed fecal and blood serum samples over a four-year period that covered the lifespan the animals.
Health and longevity
The study reported that regardless of exercise, the healthiest and longest living animals were in the low-fat, calorie-restricted group. Even when compared with those in the other low-fat groups. In addition, animals in the low-fat, calorie-restricted group were reported to have lower levels of serum endotoxin. The median lifespan and maximum lifespan was increased by approximately by 20% and 25%, respectively in the low-fat calorie-restricted group.
In contrast, the high-fat group had the shortest lifespan and poor health. However, animals in this group who were on the high-fat, calorie-restricted diet were reported to have a longer lifespan that was comparable to that observed in the non-calorie-restricted, low-fat groups.
Interestingly, unlike the low-fat group, a favorable effect of voluntary exercise was observed in the non-calorie-restricted, high-fat group with increases in the median and maximum lifespans of around 13% and 18% respectively.
The study also reported changes in the composition of the microbiota of the gut between the low-fat diet and high-fat diet groups. And all animals were observed to have changes in their gut microbiota during the later life stages.
In particular, the shift of gut microbiota was more pronounced in the low-fat, calorie-restricted group. This groups was observed to have higher levels of some microorganisms such as those in the Lactobacillus genus.
Members of this genus have been reported to benefit gut barrier function, thus preventing endotoxins from passing into the bloodstream, and also lower levels of certain microorganisms known to be potentially harmful.
The changes in microbiota of the gut in the high-fat group late in life could not be determined. Unfortunately, all the animals in this group had died by that time.
What does this mean for humans?
It remains to be determine how findings from this Nature study can be extended to humans for healthier aging.
The experimental dietary extremes regarding fat composition and caloric restriction used in animal studies offer interesting insights into modulation of gut microbiota. Further investigations of other dietary manipulations representing more usual diets will determine the utility of calorie restriction and the impact on gut health.
Not all calories are the same, and it would be prudent not to compromise nutritional adequacy in light of calorie restriction. Your best plan is to restrict the consumption of excessive calories or “empty calories” from nutrient-poor foods for overall health and well-being.
Prolon’s Fasting-Mimicking Diet is scientifically-formulated to increase cellular regeneration and longevity.
Limited Offer! 20 FREE Fast Bars and FREE Shipping. And Save an Extra 15% OFF with discount code KALDZAR!
Kaldzar is supported by its audience. When you purchase through links on our site, we may earn an affiliate commission.