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Aging is the one thing we all have in common. We will inevitably all progress with age, but how it affects us will depend on several factors, including genetics, the environment, and our lifestyle.
There’s another factor that can drive or maybe even slow the aging process, the gut microbiome. Here, we’ll explore what aging is, some of the metabolic and biological processes that underpin getting old, and the impact of the gut microbiome.
In scientific terms, aging is the time-related decline in physiological processes necessary for survival and fertility[i], ultimately contributing to death. On the face of it, most of us associate aging with physical features, such as:
However, these physical manifestations arise because of aging at both a cellular and systemic level. Although aging may be noticeable, it is a complex phenomenon underpinned by many cellular processes.
Scientists believe the human lifespan is fixed at a limit of around 122 years[ii]. However, that’s not the same thing as life expectancy which is on the rise. In the US, average life expectancy at birth is 73.5 years for men and 79.3 years for women[iii].
Yet, there are several ‘blue zones’ across the world, a place where there is an unusually high number of people who live to at least 100 years old[iv]. Japan has the highest percentage of centenarians in the world, suggesting that with a healthy lifestyle, aging can be slowed down.
In recent years, scientists have begun to identify the cellular and molecular signs of aging.
DNA or deoxyribonucleic acid is the genetic information we inherit from our parents and is critical for our development and functioning[v]. However, DNA is relatively sensitive and is consistently being damaged by both internal and external factors. A prime example is the damage too much ultraviolet (UV) light from the sun can do to your skin.
It's estimated that up to 1000000 DNA lesions happen in a cell each day, many of them are efficiently removed but some pass through undetected, cannot be repaired, are repaired wrong, or are not fixed early enough. In time, these injuries to your DNA, also known as genome instability, continue to build up, contributing to aging.
DNA damage leads to cell death and senescence contributing to loss of function in your cells and organs, inflammation, and cancer development[vi].
A telomere is a region of repeated DNA sequences at the end of a chromosome. Telomeres protect the end of the chromosome from becoming frayed or tangled, like an aglet at the end of your shoelace.
Every time a cell divides, a piece of the telomere is lost, meaning telomeres shorten as you age. When a critical telomere length limit is reached, the cell undergoes senescence or cell death, also known as apoptosis[vii]. This increases the risk of loss of cells and tumor growth[viii].
Interestingly, telomere length can be preserved which helps to slow down aging and lower the risk of developing cancer by eating a diet that’s high in antioxidants, such as:
|
Tuna |
Flax seeds |
Tomatoes |
|
Salmon |
Green tea |
Olives |
|
Herring |
Broccoli |
Chia seeds |
|
Mackerel |
Red grapes |
Kiwi |
You can also support your telomere length further by limiting your exposure to:
A study by Jaskelioff et al., (2011) demonstrated that reactivating telomerase, the enzyme responsible for maintaining telomere length, in mice with severe telomere dysfunction reversed neurodegeneration, reduced DNA damage signaling, and extended telomere length[ix].
‘Inflammaging’ is the age-related increase in inflammation, characterized by an increase in circulating pro-inflammatory biomarkers in the blood and tissues. This type of chronic inflammation is strongly associated with many diseases that are common in the elderly population[x].
When you’re younger, inflammation is generally a result of an injury or infection which clears once the injury has healed, or the infection has stopped. But chronic, low-grade inflammation is a contributory factor to aging tissue and illnesses, including:
Lavin and colleagues (2020) investigated the ability of regular exercise to delay or lower the onset of inflammaging. The researchers discovered that regular and lifelong aerobic exercise reduces the level of proinflammatory factors in the blood and generally promotes an overall anti-inflammatory profile. This suggests that exercise can serve as a good anti-inflammatory activity and has the potential to protect against age-dependent inflammation[xii].
The gut microbiome is integral to human health. It’s so powerful that it is often called the body’s ‘second brain’. The gut-derived ecosystem is colonized by bacteria, fungi, protozoa, and viruses, collectively making up the microbiome. However, the world within your gut is more than just a colonic zoo of microorganisms, it has several important functions for your body and wider health.
Gut microbes:
The gut microbiome is also key to healthy aging through its influence on the immune system, inflammation, and as a general biomarker for health.
The development of the human gut microbiome is strongly believed to begin from birth. For babies born naturally, the gut is rapidly colonized by microbes from the birth canal, like Lactobacilli.
Microbiome diversity increases in the first year of life. From around 2.5 years of age, it resembles an adult microbiota in terms of diversity, composition and function, having been influenced by the infant's diet and environment[xiv].
The gut microbiome isn’t static and can be altered by various lifestyle and environmental factors, and age is no exception.
As you age, the gut microbiome becomes less diverse, with commensal genera such as Bacteroides, Bifidobacteria, and Lactobacilli declining in numbers and opportunist pathogens, like C. difficile increasing.
It’s not just the diversity and composition that’s affected. As you age, the metabolic capacity of the microbiome reduces, too, including the production of metabolites like SCFAs which could influence:
As aging occurs, the gut microbiome becomes less diverse, and the shift towards an unhealthier dominance within the gut can lead to dysbiosis[xv]. This imbalance in the gut microbial community is linked to the development of disease.
In the elderly, an altered bacterial composition and a ‘leaky gut; contribute to the escape of microbes and their by-products through the intestinal barrier, instigating an inflammatory response. Therefore, this increases the risk of both gut and systemic illnesses because of changes in the gut-brain axis, blood-brain barrier, and gut-liver axis[xvi], accelerating the rate of aging.
The gut has a direct communication pathway with the brain, they effectively have each other on speed dial, called the gut-brain axis. Numerous studies have shown that microbial imbalances in the gut microbiome and changes in the production of specific bacterial metabolites can influence brain health and function, raising the risk of mood changes, cognitive decline, and neurodegenerative diseases, like Alzheimer’s and Parkinson’s Disease[xvii].
Aging cannot be reversed. Once the damage has occurred in the cells there is very little you can do to undo it. However, it is possible to slow down subsequent aging by making healthier changes to your lifestyle.
Following a healthy diet and staying as active as possible are critical to slow down the physical signs of aging and keeping the body’s cells functioning optimally for as long as possible.
Keeping the gut microbiome in balance is also crucial because issues such as dysbiosis and a compromised gut barrier can contribute to inflammaging and the development of disease, but it also produces some key ‘anti-aging metabolites’:
Aging is just a fact of life. Even though it cannot be undone, there are things we can do to slow down its progress or make it easier to deal with. Emerging research is showing that the gut microbiome could play a pivotal role in slowing or advancing aging. By better understanding the connection between aging and the intestinal community, we can gain better knowledge of how the gut microbiome can be manipulated to promote health and longevity.
Written by: Leanne Edermaniger, M.Sc. Leanne is a professional science writer who specializes in human health and enjoys writing about all things related to the gut microbiome.
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