By: Dr. Shaina Cahill, Ph.D. (Director Medical Communications & Affairs)
Aging is a natural process that affects everyone, and the gut microbiome is no exception. Our gut microbiome undergoes its most extensive changes at both extremes of life, during infancy and old age 1–6. During aging, which affects physiological, genomic, metabolic, and immunological functions, a healthy gut microbiome has been identified as crucial for overall health and well-being in older adults 3,7–11.
Interest in the gut microbiome in the context of aging has increased in the last 10 years. Yet, the idea that health and lifespan could be enhanced and prolonged by changing the gut microbiome has been around for over 100 years 12–14. As people age, the composition of their gut microbiome changes, leading to a range of effects on health and well-being 2–4,6,12,13,15–17. So, in this blog, we will discuss the impact of aging on the gut microbiome, how it can influence health and what we can do to prolong our lives through our gut.
The aging gut microbiome
The composition of the gut microbiome changes over time and is influenced by various factors, including diet, medications, and environmental exposures 18–22. As people age, the composition of their gut microbiome changes, with a decrease in diversity and functionality and a shift in the relative abundance of certain bacteria 2–4,6,12,13,15–17. Studies have shown that the gut microbiome of older adults is significantly different from that of younger adults 4,16,23–27. While there is no threshold or age at which the microbiota composition alters to being “old,” its stability deteriorates gradually over time, and research highlights some consistent changes that appear to define an aged gut microbiome 2,4,16,23,28.So, what defines an aged gut microbiome?
- Decreased microbial diversity, specifically bacteria belonging to the phyla Firmicutes and Actinobacteria 1,2,9,13,23–27,29–33.
- Increased representation of Proteobacteria 1,9,25,30,33
- Increased abundance of bacteria associated with pro-inflammatory effects, such as Enterobacteriaceae and Clostridia 4,13,19,34
- Reduced abundance of beneficial bacterial species such as Bifidobacterium and Lactobacillus 4,13,15,19,35.
Effects on health
Maintaining gut health for older adults is paramount as the gut microbiota may modulate aging-related changes related to immunity, inflammation, frailty, neurodegenerative diseases (i.e. Alzheimer’s disease), and cognitive function 1,4,13,23,25,34,36,36–42. Age-related gut dysbiosis may result from altered lifestyle, dietary modification, increased medication use, weakened immune strength and decreased physical activity, all commonly associated with senescence 1,4,16,17,19,24,28,30,34,39,43–49.
How to impact gut aging: diet and physical activity
The changes in the gut microbiome that occur with aging can be actively influenced by diet and physical activity, making these areas to focus on when making improvements to counteract aging 2,3,9,50–52. Both diet and physical activity are found to decline in later life, and while important throughout one’s life, their effects seem to be exaggerated in older individuals 2,3,50–52
Studies have shown that in the elderly, diet can often decline, often found to be high in refined carbohydrates and low in dietary fibre and protein, lacking diversity, which is associated with a depleted microbiome and an elevated risk of developing chronic diseases 1,4,6,9,53. One possible way to curb gut dysbiosis in the elderly is to target diet, as alterations in diet are known to impact the gut microbiome in 24 hours 46,51. The importance of diet cannot be overstated, as we know that the more diverse the diet, the more diverse the microbiota, which has been linked to improved health and reduced frailty 1,2,51.
A sedentary lifestyle can lead to an altered gut microbiome, and the elderly who maintain a physically active lifestyle report fewer GI symptoms, improved gut microbiota composition and better well-being 9,54–57. In addition, signs of depression and anxiety were lower in active seniors, indicating physical activity can impact both gut and overall health and have far-reaching and important effects on senior health 9,54.
The gut microbiome is a complex and dynamic system affected by aging 4,16,18–27. Studies have shown that the composition of the gut microbiome changes with age, leading to an increased risk of chronic diseases, gastrointestinal issues, and cognitive decline 2–4,6,12,13,15–17,25,58–60. Both diet and lifestyle habits can influence the composition of the gut microbiome and should be considered when making health-related decisions 2,3,9,50–52. As more research is conducted in this area, it is becoming increasingly clear that the gut microbiome plays an important role in overall health and well-being.
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Team Novel Biome
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