Longevity Supplement Combo Boosts Muscle Mass and Endurance, New Study Shows

Highlights 

• Of eight dietary fiber types, FOS most greatly increases the beneficial gut bacteria metabolite urolithin A.
• FOS combined with the urolithin A precursor EA synergistically increases endurance and muscle mass. 
• The combo also synergistically increases mitophagy—a key cellular process that counteracts biological aging.  

As we age, our muscles shrink, and the beneficial bacteria living in our gut dwindle. While appearing unrelated, emerging evidence suggests that dwindling beneficial gut bacteria contribute to muscle shrinkage. This notion is supported by a new study showing that one treatment, FOS and EA, improves these seemingly disparate aspects of aging. 

Fructooligosaccharide: The Best Fiber for the Job 

When we consume food, we never eat for just one. Trillions of living microscopic organisms (microbes), mostly bacteria, living in our gut need feeding too. Our gut bacteria primarily feed on fiber—the carbohydrates we can’t digest—leading to the generation of various metabolic byproducts. Some strains of bacteria produce beneficial byproducts, such as short-chain fatty acids, which protect against age-associated inflammation but decline with age. 

Our gut bacteria also feed on plant-based molecules called polyphenols, including EA, which is found in foods such as pomegranates, raspberries, and walnuts. Certain strains of bacteria metabolize EA into a beneficial byproduct known as urolithin A (Uro-A). Interestingly, only 40% of people are said to have gut bacteria capable of generating meaningful levels of Uro-A. However, Uro-A is associated with counteracting muscle aging—loss of muscle size and strength.  

Considering that Uro-A may play a key role in mitigating muscle shrinkage, researchers in China sought to determine which type of fiber best promotes its production. The researchers tested eight different fiber types on human gut bacteria and found that Uro-A levels were elevated the most by FOS, a type of fiber found commonly in chicory root, bananas, and agave. Based on these results, the researchers chose to proceed with FOS for the remainder of their experiments. 

Effect of Combining FOS and EA 

To test the effects of FOS and EA on muscle function, the Chinese researchers fattened up some mice. To do so, they fed mice a high-fat diet, a common method for inducing obesity in mice. In addition to excess body fat, obese mice exhibit reduced muscle mass and strength, similar to what can be seen in aged mice. Meanwhile, another set of mice was fed a normal chow diet. Subsequently, the obese mice were given either FOS alone, EA alone, EA combined with FOS, or Uro-A. 

FOS and EA Synergistically Improve Endurance and Muscle Mass 

As a proxy for muscle function, the researchers measured maximum aerobic speed (MAS). This involved placing mice onto a treadmill and having them run with increasing speeds until they could no longer maintain their pace. The pace at which they could no longer run was considered their MAS. The results showed that obese mice fed EA combined with FOS performed just as well as obese mice fed Uro-A. However, obese mice fed either EA or FOS alone performed just as poorly as untreated obese mice. 

Similarly, the muscle mass of obese mice fed EA and FOS was the same as that of obese mice fed Uro-A. Moreover, the muscle mass of obese mice fed EA or FOS alone was the same as that of untreated obese mice. Together, these findings suggest that, relative to EA or FOS alone, combining EA and FOS is necessary to improve endurance and muscle mass in obese mice. Considering that EA and FOS have no significant effect unless combined, the researchers conclude that these longevity supplements work synergistically to improve endurance and muscle mass. 

FOS and EA Synergistically Improve Mitophagy 

Uro-A works by activating a cellular process called mitophagy, whereby unhealthy mitochondria are degraded and their parts recycled. Mitophagy plays a critical role in maintaining the health of our mitochondria, which are the structures responsible for producing cellular energy. Without properly functioning mitochondria and sufficient levels of cellular energy, our muscles cannot function correctly. Thus, if impaired mitophagy goes untreated, our muscles will shrink, leading to strength and mobility loss.   

Compared to normal mice, obese mice exhibited a reduction in mitophagy, which could account for their reduced endurance capacity and muscle mass. Moreover, treating the obese mice with either FOS or EA had no significant effect on mitophagy. In contrast, combining FOS and EA significantly elevated mitophagy to levels similar to those of Uro-A. Overall, these findings suggest that combining FOS and EA counteracts muscle shrinkage by increasing Uro-A and activating mitophagy.

Why Not Just Take Urolithin A? 

Compared to a Uro-A supplement, such as Mitopure, which costs $125 for a month’s supply, FOS and EA supplements may be more cost-effective. However, this depends on the brand of Uro-A, FOS, or EA. When it comes to supplements, which are not regulated by the FDA (Food and Drug Administration), it’s best to go with brands that have been third-party tested for quality. 

With that being said, the perfect solution to age-related muscle loss (sarcopenia) requires further investigation. Resistance exercise and adequate protein intake are among the most well-researched methods for maintaining muscle mass and strength with age. The contribution of gut bacteria and Uro-A levels to muscle size with age may vary from individual to individual. 

The specific strains of bacteria residing in our gut depend largely on our diet. While FOS was shown to boost Uro-A more than other types of fiber, most foods contain multiple types of fiber. It follows that a diet rich in fiber from a variety of fruits, vegetables, nuts, seeds, legumes, and grains may be enough to feed the beneficial gut bacteria that make Uro-A.