With our current knowledge, aging is unbeatable, there is no magic fountain of youth. It is a complex process and and the slow wearing off of our tissues and cells is inevitable. However, humans are very curious by nature, when something seems unbeatable, it only fuels our determination. So, researchers are constantly investigating the process of aging from various aspects trying to find and piece together the puzzle.
The gut microbiome is an interesting new piece of this puzzle. The gut microbiome consists of a community of tiny living organisms (microbes, such as bacteria, viruses, fungi) that take up residence in our guts. What's in it for them: food and a comfortable, safe, cozy environment. What is the benefit for us: vitamins, hormones, minerals, maintenance work in the gut etc. But only if we rent the place for 'good' bacteria. In other words, normally, we have a symbiotic relationship with our microbiome. In case, the balance of the microbe community is disturbed (dysbiosis), 'bad', pathogenic bacteria may grow causing disorders (e.g. gastritis, ulcers, unhealthy aging).
So, what is a healthy microbiome?
It varies individually, it is unique, just like our fingerprints. Depending on factors like lifestyle, age, environment, diet, physical activity, medical treatment, gender. Thus, it would be difficult to define the composition for a healthy microbiome. However, there have been studies that compared the microbiomes of centenarians and younger people struggling with non-communicable diseases. The conclusion was that the microbe community was more diverse in case of centenarians and the ratio of ‘unhealthy’ and ‘healthy’ bacteria was more balanced as well (Ghosh, Shanahan, & O’Toole, 2022).
The significance of microbiome diversity in the guts may be gripped by a simple analogy to human societies. A society works most effectively if it is made up of individuals with different skills, who are allowed to do what they do best based on their strengths. If key professions/skills would be missing, the society would struggle, and chaos would be likely. Similarly, the microbiome functions best and withstands disturbances (in other words, it is resilient), when it is diverse.
Why is it good for us to let microbes thrive (rent a place) in our gut?
Under ideal conditions, a healthy gut microbiome helps us stay healthy in many different ways.
1. Anti-inflammatory effect: Chronic inflammation is a very important factor in aging, often referred to as inflamm-aging. An overproduction of inflammatory mediators results in a weaker immune system, an increased risk of metabolic disorders (diabetes) and cancer. So, preventing chronic inflammation is important and there are microbes who help us. For example, Faecalibacterium prausnitzii produce anti-inflammatory molecules, like short-chain fatty acids (SCFA) from dietary fibers (Kunst et al., 2023).
2. Reduce oxidative stress: In unhealthy aging, there is usually an imbalance in production and elimination free radicals or reactive oxygen species (ROS). These molecules are crucial 'weapons' against pathogens or tumor cells, however, their overproduction results in harming our own cells and induces inflammation. There are bacteria in our guts that are dedicated to either produce (e.g. Lactobacillus species, Enterococcus faecalis) or eliminate (e.g. Bifidobacterium longum, Lactobacillus plantarum) them depending on our needs (Kunst et al., 2023).
3. Body weight management: Obesity is also closely associated with aging and as fat tissue is the source of signaling molecules promoting inflammation, reducing fat accumulation is also an important aspect of healthy aging. The role of gut microbiome in this struggle is complex. It regulates fat absorption, appetite, insulin production and fat accumulation (Van Hul & Cani, 2023).
4. Neuroprotection: Cognitive impairment is often considered an inevitable consequence of aging. Though, a decline in cognitive skills is part of healthy aging, its progress is associated with gut health. This finding immediately put the guts into the spotlight. Direct and indirect connections have been described between the gut and the brain (gut-brain axis). The microbiome plays a significant role in maintaining cognitive health, as the SCFA produced by bacteria helps maintaining the blood-brain barrier (a lavery tightly connected layer of cells protecting the brain), synthesize neurotransmitters (e.g. serotonin, GABA), affect neural development and synaptic plasticity (Loh et al., 2024).
5. Production of vitamins and minerals: A diverse bacterium population (including species like Bifidobacterium, Lactobacillus, Bacteriodes) in our guts provide us with B vitamins (e.g. biotin, cobalamin, folates, nicotinic acid, panthotenic acid, pyridoxine, riboflavin and thiamine), vitamin K and support the absorption of minerals (iron, zinc, magnesium). and coenzim Q10. Vitamin K is essential for blood clotting, and bone health, while B vitamins take part in DNA repair, help the normal functioning of the nervous system (LeBlanc et al., 2013).
How to nurture the microbiome:
Probably one of the most important factors in regulating the composition of the gut microbiome is food. If we nurture the right types of bacteria in the guts, they can help us stay healthier and younger for a longer period of time. There are some ways that may help maintaining a thriving gut microbe community:
1. Fermented, probiotic foods: Fermented foods offer two major benefits for the gut microbiome. The first one is that they contain living microbes and help maintain a healthy composition of microbes, prevent the overgrowth of pathogenic bacteria. Thus, they are probiotics. The other benefit is that fermentation process increases the availability of several nutritients (vitamins, minerals, sugars), as it is technically a pre-digestion process (Das et al., 2020; Sharma & Padwad, 2020).
Examples for fermented, probiotic foods: kombucha, kefir, yogurt, fermented soy products (natto, tempeh), rice wine, kimchi, sauerkraut.
2. Prebiotics: Prebiotics are complex, non-digestible carbohydrates, like fibers that are fermented by bacteria to SCFA, which are beneficial to us with, for example, the anti-inflammatory effect (Shi, Ma, Sakandar, Menghe, & Sun, 2022).
Examples for prebiotic foods: whole grains, bananas, greens, onions, garlic, soybeans and artichokes.
3. Mediterranean diet: It is widely accepted that the mediterranean diet has health benefits; it reduces the risk of diabetes, obesity, Alzheimer's disease and cardiovascular disorders. It has been shown recently, that this diet changes the composition of the gut microbiome; helps 'good' bacteria to thrive and suppresses the growth of 'bad' bacteria. Altogether, it reduces inflammation, has antioxidant effects and fights aging (Ghosh et al., 2020; Gundogdu & Nalbantoglu, 2023).
Typical foods and nutritients in the mediterranean diet that contribute to the beneficial effects:
Vegetables, fruits - fibers, antioxidants
Legumes - fibers
Extra-virgin olive oil - healthy fats (monounsaturated fatty acids), polyphenols
Red wine - polyphenols, antioxidants
Fish - healthy fats (polysaturated fatty acids, like Omega-3)
Wholegrains - fibers, vitamin B
Nuts and seeds - polyphenols, healthy fats (poly- and monounsaturated fatty acids)
Certain types of cheese - probiotics
While we are still quite far from finding a cure for aging, nourishing our gut microbiome is a promising step forward. A balanced, diverse microbiome aids healthy aging and staying sharp, so take good care of the microbe community renting a place in your guts!
Sources:
Das, G., Paramithiotis, S., Sundaram Sivamaruthi, B., Wijaya, C. H., Suharta, S., Sanlier, N.,Patra, J. K. (2020). Traditional fermented foods with anti-aging effect: A concentric review. Food Res Int, 134, 109269. doi:https://doi.org/10.1016/j.foodres.2020.109269
Ghosh, T. S., Rampelli, S., Jeffery, I. B., Santoro, A., Neto, M., Capri, M., O'Toole, P. W. (2020). Mediterranean diet intervention alters the gut microbiome in older people reducing frailty and improving health status: the NU-AGE 1-year dietary intervention across five European countries. Gut 69(7), 1218-1228. doi:https://doi.org/10.1136/gutjnl-2019-319654
Ghosh, T. S., Shanahan, F., & O’Toole, P. W. (2022). The gut microbiome as a modulator of healthy ageing. Nature Reviews Gastroenterology & Hepatology, 19(9), 565-584. doi:https://doi.org/10.1038/s41575-022-00605-x
Gundogdu, A., & Nalbantoglu, O. U. (2023). The role of the Mediterranean diet in modulating the gut microbiome: A review of current evidence. Nutrition, 114, 112118. doi:https://doi.org/10.1016/j.nut.2023.112118
Kunst, C., Schmid, S., Michalski, M., Tümen, D., Buttenschön, J., Müller, M., & Gülow, K. (2023). The Influence of Gut Microbiota on Oxidative Stress and the Immune System. Biomedicines, 11(5). doi:https://doi.org/10.3390/biomedicines11051388
LeBlanc, J. G., Milani, C., de Giori, G. S., Sesma, F., van Sinderen, D., & Ventura, M. (2013). Bacteria as vitamin suppliers to their host: a gut microbiota perspective. Current Opinion in Biotechnology,24(2),160-168. doi:https://doi.org/10.1016/j.copbio.2012.08.005
Loh, J. S., Mak, W. Q., Tan, L. K. S., Ng, C. X., Chan, H. H., Yeow, S. H., . . . Khaw, K. Y. (2024). Microbiota–gut–brain axis and its therapeutic applications in neurodegenerative diseases. Signal Transduction and Targeted Therapy, 9(1), 37. doi:https://doi.org/10.1038/s41392-024-01743-1
Sharma, R., & Padwad, Y. (2020). Probiotic bacteria as modulators of cellular senescence: emerging concepts and opportunities. Gut Microbes, 11(3), 335-349. doi:https://doi.org/10.1080/19490976.2019.1697148
Shi, X., Ma, T., Sakandar, H. A., Menghe, B., & Sun, Z. (2022). Gut microbiome and aging nexus and underlying mechanism. Applied Microbiology and Biotechnology, 106(17), 5349-5358. doi:https://doi.org/10.1007/s00253-022-12089-5
Van Hul, M., & Cani, P. D. (2023). The gut microbiota in obesity and weight management: microbes as friends or foe? Nature Reviews Endocrinology, 19(5), 258-271. doi:https://doi.org/10.1038/s41574-022-00794-0 Assessed and Endorsed by the MedReport Medical Review Board
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