Gut microbiota and aging
Human life expectancy continues to increase, leading to a rise in the aging population. According to the United Nations “World Population Ageing” report, the number of people aged 60 and older will double to more than 2 billion by 2050.
Aging is related with decline in physiological, genomic, metabolic, and biologics functions.
Aging also is related to alteration of the intestinal microbiota and multiple disease processes (López-otín et al., 2013). The composition of our gut microbiota changes during life; it is affected by our diet, genetics, medications, pathological conditions, physiological changes, physical activity levels, and lifestyle choices. Reduced diversity and overgrowth of pathogens are the main features of the elder microbiota.
As we age, the diversity of our microbiota declines. The gut microbiota is home to an enormous and complex community of bacteria providing benefits to our body in many ways, including, but not limited to, digestion, metabolization of nutrients, immunity, and production of bioactive chemical compounds, such as vitamin K and B.
The digestive tract is subject to a variety of changes due to aging: impaired dentition and salivary function, decreased intestinal motility with constipation and diverticular disease. Together, these factors can contribute to changes in the microbiome among older and can cause or contribute to the development of disease or increase fragility and sensitivity to inflammation.
The microbiome’s role in shaping the immune system starts early in life, with continued influence on immune responses throughout the lifetime.
Studies that explored elderly fecal content found a reduction in beneficial bacteria such as Bifidobacteria Bacteroides and lactobacilli, (Hopkins & Macfarlane, 2002), (Zwielehner et al., 2009) with a decrease in both numbers and species diversity (E. J. Woodmansey, 2007),(Emma J. Woodmansey, 2004)and an increase in pathogenic bacteria such as enterobacteria, C. perfringens and C. difficile (Nagpal, 2018).Another study investigating changes in the gut microbiome of various age groups found that in the very elderly (> 80 years) there were significantly higher counts of Lactobacillus and Akkermansia bacteria and decrease in the presence of Bifiocabterium compared to middle-age adults and the younger elderly (Salazar et al., 2019). These findings may indicate a potential association of the presence of high levels of some of these bacteria with, longevity.
A third study that examined the correlation between the gut microbiome and healthy aging on a cohort of extreme elderly (≥ 90 years old) people in China revealed that the long-lived group had greater gut microbiome diversity than the younger adult control group ( (Kong, 2019). Similar results were also obtained in a study conducted in Italy (Biagi et al., 2016).
The role of Prebiotics
Prebiotics are defined as non-digestible food ingredients that have a favorable effect on the host by stimulating the growth and/or activity of beneficial bacteria in the colon (Gibson et al., 2010). Prebiotics have been explored in thousands of human studies, mainly in context to their positive effects on the modification of human gut microbiota specifically promoting beneficial microbes and suppressing harmful bacteria.
Prebiotics have also been observed to have anti-inflammatory effect and positively modulate the immune system in elderly people (Vulevic, 2008)
A study that assessed the effect of a prebiotic mixture compared to placebo on immune function and fecal microflora composition in healthy elderly subjects for 10 weeks showed that the prebiotic mixture significantly increased the numbers of beneficial bacteria, especially bifidobacteria, at the expense of less beneficial groups compared with the baseline and placebo. Significant increases in phagocytosis, NK cell activity, and the production of anti-inflammatory cytokine interleukin-10 (IL-10) and significant reduction in the production of proinflammatory cytokines (IL-6, IL-1β, and tumor necrosis factor-) were also observed (Vulevic, 2008).
The fermentation of prebiotics by beneficial bacteria in the colon results in the production of short-chain fatty acids (SCFAs) that contribute to the maintenance of the digestive tract and regulating the activation of immune/inflammatory responses (Vinolo et al., 2011).
SCFAs have other significant beneficial impacts on metabolic and physiologic health, such as maintaining a low luminal pH, increasing the microbial biomass, fostering the growth of beneficial bacterial population, promoting and regulating mucus production, supporting gut barrier integrity and gut homeostasis, and shaping the peripheral metabolism(
The acidification of the intestinal environment by SCFAs, limits the colonization of undesired bacteria and stimulates nutrients absorption. In addition, they are important signaling molecules in the microbiota-host interaction and have been shown to modulate leukocyte development, survival, and function (Corrêa-Oliveira et al., 2016).
Aging has been associated with a progressively and statistically significant reduction in the fecal concentrations of SCFAs (Nagpal, 2018). The age-related declination in SCFA levels is thought to be associated with aging-related health conditions, such as irregular bowel movements, reduced appetite, frailty, weight loss, cognitive decline, hypertension, vitamin D deficiency, diabetes, arthritis, and sarcopenia (Ríos-Covián et al., 2016). This decline can negatively affect host immune health and inflammation and eventually cause various gut-related diseases in elderly persons.
With such strong evidence that beneficial bacteria in the digestive tract have significant influence on host nutrition and metabolism, and that the microbiota-derived metabolites such as SCFAs are readily absorbed in the plasma of the host via the intestinal epithelium (Besten et al., 2013), it can also be surmised that a healthy digestive tract can have an important and direct effect on the wellbeing of elderly population.
Bioecolians: Beyond Prebiotics
Biocolians is an effective prebiotic obtained from sugars via a precisely controlled enzymatic process. Bioecolians is an alpha-gluco-oligosaccharide composed of short glucose chains linked by glycosidic (α1-2) and (α1-6) bonds. Bioecolians promotes the growth of beneficial bacteria and reduces the number of harmful bacteria in the gut.
An in vitro fermentation study of Bioecolians and human fecal microbiota showed a significant increase of the Bifidobacterium sp. compared to the control (Sarbini, 2013). A pre-clinical trial compared the effect of Bioecolians and other oligosaccharides on the intestinal microflora in rats inoculated with a human fecal flora (Djouzi, 1997). In the latter study, the production of SCFAs in the Bioecolians treatment group was substantially higher than in the control group. A clinical study showed an increase in Lactobacilli and Bifidobacterial colonies, coupled with high production of SCFAs following the consumption of Bioecolians.
Bioecolians, could help promote healthier aging by increasing the number of beneficial bacteria in our digestive tract. These “good” bacteria are associated with better health, reduced disease risk, and better aging.
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