This combination may promote healthy skin aging despite harmful UV radiation(Artem Tryhub | iStock)
· NMN and the gut bacterium L. fermentum eliminate harmful molecules called free radicals.
· The combination of NMN and an intestinal bacterium synergistically protects mouse skin from harmful ultraviolet radiation.
The skin is one of the most complex organs in our bodies and has an integral connection to the gut. Skin anti-aging has become a research hotspot of many scholars and clinicians and has captivated the attention of many beauty seekers. So, what if we could harness what we know about this connection to improve skincare?
Zhao and colleagues from the Chongqing University of Education in China published a study in Frontiers in Pharmacology showing that combining an intestinal bacteria with nicotinamide mononucleotide (NMN) synergistically improved mouse skin damage caused by ultraviolet (UV) irradiation. They found that mice that drank water containing NMN (300 mg/kg) along with Lactobacillus fermentum extract saw greater protective effects than either NMN or the bacterium individually. These findings suggest that NMN and the bacterium provide skin protection through different pathways and that using them together may provide a means to enhance skin health.
Photoaging is premature aging of the skin caused by repeated exposure to UV radiation, primarily from the sun but also from artificial UV sources. The occurrence and development of skin photoaging mediated by UV radiation involve multiple pathways, including inflammation and responses to oxidative stress. Studies have shown that intestinal bacterial composition can modulate skin inflammation and that skin UV radiation exposure alters the gut bacterial composition. Figuring out how to utilize the skin-gut connection could enhance the way we protect our skin from the sun’s harmful ultraviolet rays.
L. fermentum bacteria have been shown to balance the composition of intestinal bacteria (the microbiome). This intestinal bacterium also can enhance the immune system, lower cholesterol levels, and reduce the presence of harmful molecules called free radicals that cause oxidative stress. The potential anti-aging properties of this intestinal bacterium along with its ability to clear free radicals has drawn the attention of researchers looking for ways to enhance skin protection and health.
Another antioxidant and anti-inflammatory compound is NMN, which boosts levels of a crucial molecule for energy production and maintenance of cell health called nicotinamide adenine dinucleotide (NAD+). There’s compelling evidence that taking NMN reduces free radicals and inflammation in organs like the liver and also provides anti-aging benefits.
Some reports indicate that both NMN and L. fermentum have a protective effect on the skin damaged by UV. For these reasons, Zhao and colleagues decided to test the protective effects of NMN and L. fermentum on skin damaged by UV radiation.
To test their antioxidant potential, Zhao and colleagues mixed NMN and the contents of the intestinal bacteria in test tubes with free radicals and measured their ability to absorb the free radicals, also known as free radical scavenging. They found that mixing NMN and the intestinal bacteria together resulted in better free radical absorption than either NMN or the bacteria alone. This combination also outperformed vitamin C, which is known to be an excellent scavenger. Since free radicals in skin cells play key roles in UV radiation-induced aging, their elimination by NMN and the bacteria may illustrate how the combination of supplements protects skin from harmful UV radiation.
Zhao and colleagues then moved their experiments from test tubes to live animals. They wanted to find out whether the free radical-reducing properties of the supplement combination could preserve skin tissue integrity in mice following intense, two-week UVB radiation exposure. Although NMN and L. fermentum had noticeable effects on their own, the research team found that mice treated with the combination of the two substances showed preserved skin tissue similar to that of mice not exposed to UVB radiation. By looking at the skin under the microscope, Zhao and colleagues could see that the treatment combination significantly preserved the dermal layer of the skin — a blood vessel-containing layer just under the surface — similar to that of mice without UVB radiation exposure.
Moreover, the number of mast cells — cells indicative of inflammation — in the dermal skin layer increased four times following UVB radiation exposure. Supplementing with NMN and L. fermentum substantially reduced the number of mast cells so that they only increased about two-fold after intense UVB radiation exposure. So, the combination treatment provided better tissue preservation than NMN or the bacteria alone, indicating a synergistic protective effect.
Previous research has shown that NMN enhances NAD+ biosynthesis to ameliorate diseases in mice through activating enzymes that maintain cell health and promote free radical removal like sirtuins. Understanding the protective effect of L. fermentum remains more elusive, though, and Zhao and colleagues say it may be related to the anti-inflammatory effects of its metabolites like short-chain fatty acids. The research team adds there’s still a great need to reach a better comprehension of the bacterium’s beneficial effects, especially when it’s combined with NMN. Moreover, we need to conduct human studies to show how effective the combination of these substances is.