• Dr. Nihan

A Small Buddy for Higher Testosterone

Meet Limosilactobacillus reuteri

We have a lot of small buddies in our bodies to help us be healthy -- and Limosilactobacillus reuteri is only one of them. Before it was reassigned to the genus Limosilactobacillus in April 2020, it was known as Lactobacillus reuteri. L. reuteri is not found only in the gastrointestinal tract but also in various natural environments. It is not a pathogen which means it doesn't cause disease. Besides, there are thousands of scientific articles about the health benefits of this small buddy!

Let's look at closer some of the benefits of this small buddy.

Effects of Limosilactobacillus reuteri

  • Neurodevelopmental disorders

  • Vitamin production

  • Testosterone levels

  • Obesity

  • Antimicrobial features

  • Intestinal health

  • Gastric health

  • Oral health

Neurodevelopmental disorders

There are a lot of factors that science is still working on naming the possible causes of neurodevelopment disorders. For example, exposure to maternal obesity in the uterus is an increased factor in certain neurodevelopment disorders, such as autism. The research indicated that L. reuteri can be a potential application in treating patients who suffer from neurodevelopmental disorders. The bacteria's regulatory function, oxytocin capacity increase, and the ability for impaired social restoration are the critical factors for treatment.

Vitamin production

Most of us are shopping for vitamin tablets, powders, or liquids to increase our well-being, right? Unfortunately, our bodies cannot synthesize the thirteen essential vitamins. So, we need to consume most of them daily, preferably in natural ways like our daily food and drink intake. Now, think about the fantastic creation of our body as a host of tiny, good bugs that can 'produce' vitamins for us! Most L. reuteri strains can produce different vitamins, such as B9 (folate) and B12 (cobalamin).

Scientists have studied the lack of vitamin B12 in female mice and their offspring. The results were precise that L. reuteri can treat the B12 deficiency. Further, some L. reuteri strains were also shown to synthesize folate along with B12.

Testosterone levels

L. reuteri is a probiotic bacterium found in most of us, our different body sites, including breast milk, gastrointestinal tract, urinary tract, and skin. This sounds very normal – but what would you think if you had heard that this little guy increases the testicle size?

Lately, people have started to talk about a magical way that increases testicle size. However, this magic depended on a scientific study conducted by Poutahidis and his colleagues in 2014. The study focused on testosterone levels and testicular size in aging mice. The results were promising since the L. reuteri provided youthful properties to the testicles of the old mice, luxuriant body hair, higher serum testosterone levels, and decreased obesity. So, scientists reported that L. reuteri may prevent age and obesity-related testicular atrophy.

After this study, many people might want to try L. reuteri as a promising supplement for their testosterone levels and masculinity. Especially some of the bodybuilders who may have shrunken testicles due to steroid use. Look at the interest: A YouTube video about this scientific study has been watched more than 1,369,900 with 13K 'like' and more than 1.7K reviews!

Two years after the above research, another group of scientists focused on anti-inflammatory L. reuteri and its probiotics benefits on aged mice. They also found that L. reuteri increased testosterone levels and decreased weight gain in treated males. At the same time, healthier skin with active hair growth was seen in females. They concluded that L. reuteri is a potential probiotic strain to improve various aspects of aging issues. It should really be worth giving a try!


For many years, the relationship between obesity and microbiota has been studied well. Interestingly, some L. reuteri strains, such as L. reuteri PTA 4659 and L. reuteri BD301, were found against weight gain and a good factor for obesity treatment and prevention. There are both animal and human studies regarding L. reuteri in obesity. It really looks like a good opportunity for obesity.

Antimicrobial features

It is also known that L. reuteri can produce antimicrobial molecules, such as organic acids, reuterin, and ethanol. Most L. reuteri strains naturally have reuterin as a well-known antimicrobial compound. Reuterin was discovered in the late 1980s. It is a novel broad-spectrum antibiotic substance through the fermentation of glycerol by L. reuteri. With all of these antimicrobial molecules, L. reuteri is effective against many gastrointestinal tract infections such as Helicobacter pylori (cause of chronic gastritis and peptic ulcers; risk factor for gastric malignancies), E. coli, Clostridium difficile, Candida and Salmonella.

In the past decades, it was shown that the decrease of L. reuteri in humans increased the inflammatory diseases. So, this bacterium can be a good suggestion as a preventive and /or therapeutic avenue against inflammatory diseases. We can group the antimicrobial mechanism of L. reuteri as below:

  1. In the body, when the pathogenic microorganisms are successfully colonized in/on a part, the infection occurs. L. reuteri was found that it can stop the pathogenic bacteria from colonizing. Further, L. reuteri can help gain the healthy microbiota composition back in the body.

  2. L. reuteri supports the host's immune system by promoting T cell development and function and reducing the production of pro-inflammatory cytokines.

  3. The colonization of L. reuteri may strengthen the intestinal barrier and thus may decrease the microbial translocation from the gut to the tissues.

Intestinal health

I believe you don't know any individual who has not ever experienced diarrhea! Yes, it is one of the most common conditions, which is very typical due to the continuous daily intake of certain foods, pathogens, and other molecules. The treatment of diarrhea is one of the well-studied effects of L. reuteri. Moreover, it was discovered that children fed with L. reuteri, while healthy, are less likely to fall in with diarrhea. There are a lot of different mechanisms for the strong effects of L. reuteri on diarrhea. Reducing intestinal motility and synthesizing antibacterial molecules are only two of these mechanisms.

The other possible effects of L. reuteri on intestinal health are

  • reducing the incidence of sepsis,

  • shortening the required duration of hospital treatment,

  • treating necrotizing enterocolitis in preterm infants,

  • and treating the infant colic.

Gastric health

Our gastrointestinal system has its own protection mechanism against pathogen microorganisms. The low pH (acidic environment) by gastric acids and bile salts in the small intestine makes the gastrointestinal system provides a harsh environment for bad/strange bugs. However, L. reuteri strains are resistant to an acidic environment and bile salts. Thanks to this feature that comes from their biofilm-making ability, they can protect themselves in the gastrointestinal system's harsh climate and serve the benefits to our bodies.

One of the most common pathogens of the gastric system is Helicobacter pylori which causes peptic ulcers. All over the world, antibiotic treatment is still popular to treat the symptoms, with lots of issues like their side effects and antibiotic resistance. However, science lights the future by using L. reuteri to treat H. pylori per the latest promising study results. It is found that L. reuteri has the potential to suppress H. pylori infection. One study showed that L. reuteri and omeprazole cure H. pylori infection at 0% to 60% compared to only omeprazole treatment.

Oral health

Our lovely friend L. reuteri is a possible hero for oral health! Streptococcus mutans is one of the bacteria that cause tooth decay (dental cavities), and L. reuteri may be capable of promoting dental health by eliminating the S. mutans with no harm to the teeth. Clinical trials also proved that if L. reuteri colonized your mouth, you have significantly fewer S. mutans.

Another possible positive effect of L. reuteri in our mouth is gingivitis. When scientists gave chewing gum containing L. reuteri to patients with gingivitis, their symptoms, such as gum bleeding and plaque formation, were decreased compared to the control group.

Now you know about our tiny friend, L. reuteri, better. Would you consider using it regularly?

Athalye-Jape, G., Rao, S., Patole, S. (2015). Lactobacillus reuteri DSM 17938 as a probiotic for preterm neonates: a strain-specific systematic review. JPEN Journal of Parenter Enteral Nutrition. 40(6):783-794.

Krasse, P., Carlsson, B., Dahl, C., Paulsson, A., Nilsson, A., Sinkiewicz, G. (2006). Decreased gum bleeding and reduced gingivitis by the probiotic Lactobacillus reuteri. Sweden Dental Journal. 30(2):55-60.

Lee, J., Yang, W., Hostetler, A. et al. (2016). Characterization of the anti-inflammatory Lactobacillus reuteri BM36301 and its probiotic benefits on aged mice. BMC Microbiology. 16,69.

Molina, V.C., Medici, M., Taranto, M.P., and Font de Valdez, G. (2009). Lactobacillus reuteri CRL 1098 prevents side effects produced by a nutritional vitamin B deficiency. Journal of Applied Microbiology 106, 467–473.

Mu, Q., Tavella, V.J., & Luo, X. M. (2018). Role of Lactobacillus reuteri in Human Health and Diseases. Frontiers in microbiology, 9, 757.

Nikawa, H., Makihira, S., Fukushima, H., et al. (2004). Lactobacillus reuteri in bovine milk fermented decreases the oral carriage of mutans streptococci. Int. Journal of Food Microbiology. 95(2): 219-223.

Poutahidis, T., Springer, A., Levkovich, T., Qi, P., Varian, B. J., Lakritz, J. R., Ibrahim, Y. M., Chatzigiagkos, A., Alm, E. J., & Erdman, S. E. (2014). Probiotic microbes sustain youthful serum testosterone levels and testicular size in aging mice. PloS one, 9(1), e84877.

Ruiz-Palacios, G., Guerrero, M.L., Hilty, M. (1996). Feeding of a probiotic for the prevention of community-acquired diarrhea in young Mexican children. Pediatric Research. 39(4:2)184A, Abstract 1089.

Saggioro, A., Caroli, M., Pasini, M., Bortoluzzi, F., Girardi, L., Pilone, G. (2005). Helicobacter pylori eradication with Lactobacillus reuteri. A double-blind placebo-controlled study. Digestive Liver Diseases. 37(1):407-413.

Thomas, C.M., Saulnier, D.M., Spinler, J.K., Hemarajata, P., Gao, C., Jones, S.E., et al. (2016). FolC2-mediated folate metabolism contributes to the suppression of inflammation by probiotic Lactobacillus reuteri. Microbiologyopen 5, 802–818.

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