Probiotic Supplements and Their Connection to Longevity

A recent scientific study published in Nature studied the unique population of China’s town of Jiaoling, which has a surprisingly high population of people older than 100 years old. Its inhabitants also eat a specific regional diet, so the goal of the study was to investigate their gut microbiota, or the population of bacteria and other microorganisms in their gastrointestinal system¹.

Bacteria of the Lactobacillus genus were highlighted as powerful antioxidative drivers of human health in older age, and raised the question: should we take more probiotic supplements to support gut health for a longer and healthier life?

Probiotic supplements - what are they?

Probiotic supplements are usually encapsulated, lyophilized, and live microorganisms which are released in our bodies with the purpose of replenishing our gut microflora. The official definition from the Food and Drug Administration and the World Health Organization for probiotics is “live microorganisms which, when administered in adequate amounts, confer a health benefit on the host”. Lately, they are not only present in pills, but also in a variety of food items like yogurts, ice cream, juices, cereal, or nutrition bars.

At any moment, an average weight/height person will have up to 7 kilograms of microorganisms in his body, most of which live in our intestines (gut). These microorganisms are mostly bacteria and some yeast species, living in symbiosis with us. They are the so-called “good bacteria” which don’t cause infections and actually provide us with benefits such as vitamin production and nutrient absorption. They also regulate the balance between the “good” and “bad” microorganisms, which usually get disturbed upon taking antibiotics, having food poisoning, or having the flu. They also help with lactose intolerance and infectious diarrhea.

Due to several reasons, you may have to reach for probiotic supplements. They are readily available almost everywhere and contain several probiotic species in high concentrations. Some of the most common types found in probiotics are Lactobacillus and Bifidobacterium².

The connection between probiotic supplements and longevity

Other than offering health benefits connected to food or antibiotic-related issues, probiotic supplements can provenly help with conditions like cancer and cardiovascular diseases in model organisms (worms, mice, and rats). It was also proven years ago that the microbial genetic composition can direct the host’s longevity (in worms), and fine-tuning the microbial gut composition and the host’s genetics might be the answer to protection from age-related diseases³.

Even more, studies on fish, fly, and bee model organisms showed how microbial metabolites and different compositions of the gut flora play a role in longevity¹.

Studies on animal model organisms also showed that gut microorganisms isolated from healthy centenarians (people older than 100) increased immune function in mice⁴. The question which arises is whether gut microbiome transplantation, which can also occur through fecal transplants, can increase longevity in people who receive the transplant. Such approaches have already been conducted in cases of inflammatory bowel disease, irritable bowel syndrome, obesity, type 2 diabetes, metabolic syndrome, and colorectal cancer, as well as C. difficile infection⁵. All of these cases showed great promise, but none of them were connected to longevity, even though they did increase the health status of recipients.

Finally, human studies showed how:

• centenarians from China have more Escherichia and Roseburia bacteria, and fewer Lactobacillus, Faecalibacterium, and Parabacteroides (and others) than younger people (6),
• compared to younger adults, centenarians have a unique gut microbiome rich in microorganisms capable of producing unique secondary bile acids⁷,
• centenarians from Sardinia have less Faecalibacterium and Eubacterium, while more Methanobrevibacter and Bifidobacterium than younger people⁸. 

The newest study from Nature, mentioned in the introduction, showed how centenarians from Jiaoling, China, present with a higher microbial diversity than younger people from the same region. They also had an increased number of Lactobacillus bacteria and a smaller number of opportunistic bacteria than younger ones did. Centenarians also had more Methanobrevibacter than younger people, as already proven by some previous studies¹. This and previous studies on centenarians elucidated the abundance of Lactobacillus bacteria, which may point to a specific gut microbial composition responsible for prolonged health and connected to a longer lifespan. Interestingly, Lactobacilli are found in almost every one of the probiotic supplements, and are generally considered “good bacteria”.

In conclusion, gut flora is very important for our overall health, and probiotic supplements exhibit great potential while providing us with many health benefits. Lactobacillus bacteria could be the most useful in regards to promoting lifespan, but supplementation (with follow-up studies) has not been tested on humans yet. Only a handful of studies have actually been performed on human subjects in regard to which probiotic microorganisms might be beneficial or present in longer-living people, which is not enough to conclude whether supplements themselves can affect aging or not.

Probiotic supplements - safety and dosage

Probiotic supplements are generally regarded as safe and rarely cause side effects. In some cases, one can develop a rash or an allergic reaction to specific species within the supplement, but that is quite rare. A person with a compromised immune system might experience some gastrointestinal side effects until the gut balance reestablishes, but there are no more severe side effects recorded.

There is also no set dosage since there are so many different probiotic species and supplement formulations. Most of them will target somewhere from 1 to 10 billion CFUs (colony-forming units, i.e. number of viable bacteria in a sample) of single-strained supplements, and up to 20 billion if the supplement contains multiple strains of microorganisms⁹. The best option to determine is to talk to a doctor or a pharmacist about your specific needs.

Literature:

1. Wu, L., Xie, X., Li, Y. et al. Gut microbiota as an antioxidant system in centenarians associated with high antioxidant activities of gut-resident Lactobacillus. npj Biofilms Microbiomes 8, 102 (2022). https://doi.org/10.1038/s41522-022-00366-0.
2. Kechagia M, Basoulis D, Konstantopoulou S, Dimitriadi D, Gyftopoulou K, Skarmoutsou N, Fakiri EM. Health benefits of probiotics: a review. ISRN Nutr. 2013 Jan 2;2013:481651. doi:10.5402/2013/481651.
3. Han B, Sivaramakrishnan P, Lin CJ, Neve IAA, He J, Tay LWR, Sowa JN, Sizovs A, Du G, Wang J, Herman C, Wang MC. Microbial Genetic Composition Tunes Host Longevity. Cell. 2017 Jun 15;169(7):1249-1262.e13. doi: 10.1016/j.cell.2017.05.036. Erratum in: Cell. 2018 May 3;173(4):1058. PMID: 28622510.
4. Yang HY, Liu SL, Ibrahim SA, Zhao L, Jiang JL, Sun WF, Ren FZ. Oral administration of live Bifidobacterium substrains isolated from healthy centenarians enhanced immune function in BALB/c mice. Nutr Res. 2009 Apr;29(4):281-9. doi: 10.1016/j.nutres.2009.03.010.
5. Nagpal R, Mainali R, Ahmadi S, Wang S, Singh R, Kavanagh K, Kitzman DW, Kushugulova A, Marotta F, Yadav H. Gut microbiome and aging: Physiological and mechanistic insights. Nutr Healthy Aging. 2018 Jun 15;4(4):267-285. doi: 10.3233/NHA-170030.
6. Wang F, Yu T, Huang G, Cai D, Liang X, Su H, Zhu Z, Li D, Yang Y, Shen P, Mao R, Yu L, Zhao M, Li Q. Gut Microbiota Community and Its Assembly Associated with Age and Diet in Chinese Centenarians. J Microbiol Biotechnol. 2015 Aug;25(8):1195-204. doi: 10.4014/jmb.1410.10014.
7. Sato, Y., Atarashi, K., Plichta, D.R. et al. Novel bile acid biosynthetic pathways are enriched in the microbiome of centenarians. Nature 599, 458–464 (2021). https://doi.org/10.1038/s41586-021-03832-5.
8. Wu L, Zeng T, Zinellu A, Rubino S, Kelvin DJ, Carru C. A Cross-Sectional Study of Compositional and Functional Profiles of Gut Microbiota in Sardinian Centenarians. mSystems. 2019 Jul 9;4(4):e00325-19. doi: 10.1128/mSystems.00325-19.
9. Miller, K., Ferira, A.J. What Amount Of Probiotics Do You Need Per Day? Your Dosage Q's Answered. MBG Health. 2022.