In an article published in the journal Human Nutrition and Metabolism, scientists discussed the role of climate change in modulating human gut microbiota composition and the aging process.
Reviewing available studies on these topics, scientists have come to the conclusion that climate change can considerably influence the bidirectional relationship between gut microbiota and aging.
Study: The interlink between climate changes, gut microbiota, and aging processes. Image Credit: Jacob_09 / Shutterstock
Impact of climate change on human gut microbiota
An induction in greenhouse gases (carbon dioxide, methane, nitrous oxide, and ozone) and a reduction in natural carbon sinks are the major causes of climate change, primarily characterized by global warming and environmental pollution.
Climate change related increases in temperature can negatively impact the growth of soil microorganisms, leading to alteration in soil microbial composition. Studies have shown that global warming can alter the ecosystem by reducing soil labile carbon, increasing Oligotrophic bacteria, and reducing fungi and Actinobacteria.
Microbial communities present in the gastrointestinal tract (gut microbiota) are also sensitive to changing climate, especially temperature and humidity. Regarding soil microbiome, studies have shown that climate change reduces the quality of soil microbiome and fertility and changes its composition.
The alteration in soil microbiome composition is expected to alter the soil cycling of phosphorus, sulfur, and nitrogen. By altering the respiration of the microbiome, climate change can further alter carbon and nitrogen levels in the soil.
The loss of soil biodiversity due to a reduction in the number of soil microbiomes can subsequently deplete the human gut microbiota. Low organic content in soil can reduce the quality and quantity of micronutrients in crops, which in turn can impair the normal functioning and metabolism of gut microbiota.
Reduced quality of food crops can change gut microbiota composition by increasing Proteobacteria abundance and reducing Bacteroides. These changes can further impact human health status by altering the production of essential micro and macronutrients in the body.
Diet and gut microbiota
The gut microbiota refers to a collection of beneficial and pathogenic microorganisms. Diet is one of the major factors that can directly modulate the composition and diversity of gut microbiota. Macronutrients, including fat, protein, carbohydrate, and fiber, have distinct effects on the gut microbiota.
The effects of probiotics and prebiotics on gut microbiota have been studied widely. Probiotics are living strains of microorganisms that, when administered in appropriate amounts, provide health benefits to the host by maintaining gut microbiota homeostasis. Prebiotics refer to non-viable dietary components that provide health benefits to the host by regulating the growth and activity of beneficial gut microbes.
An interaction between probiotics and prebiotics is required to produce short-chain fatty acids, which play essential roles in maintaining intestinal barrier integrity, secreting gut hormones, preventing inflammation and carcinogenesis, and regulating chromatin.
Evidence indicates that probiotic bacteria can regulate cellular senescence and age-related degeneration through a range of nutritional and immunomodulatory activities. This highlights that diet can influence the aging process through its action on gut microbiota. Changes in gut microbiota because of poor nutritional status can, thus, significantly impact health status in humans.
Gut microbiota and human aging
The gut microbiota is known to play a significant role in regulating many physiological processes, including metabolism, the immune system, and the neuropsychiatric system. Any imbalance in gut microbiota composition and diversity (dysbiosis) can lead to health complications.
A recent model of the aging hallmark highlights an association between gut microbiota dysbiosis and the onset of the aging process. It has been observed that a reduced abundance of microbial species that produce butyrate is associated with health conditions. Although gut microbiota richness increases with age, older adults exhibit a reduced abundance of bacterial species that constitute the core microbiota.
Reduced production of short-chain fatty acids and secondary bile acids and increased production of lipopolysaccharides by the gut microbiota can result in chronic, low-grade inflammation, the hallmark of many age-related diseases.
The communication between gut microbiota and the brain (the gut-brain axis) occurs through various pathways, including the vagus nerve, enteric nervous system, immune system, and tryptophan metabolism. These pathways involve a number of metabolites that are produced by the gut microbiota, including short-chain fatty acids, branched-chain amino acids, and peptidoglycans.
An imbalance in beneficial and pathogenic bacterial abundance can impact age-related physical capacities by inducing inflammation, reducing lean muscle mass, altering lipid metabolism, and reducing vitamin levels. A high abundance of beneficial bacterial communities is associated with an anti-inflammatory response, improved mitochondrial respiration, and increased production of short-chain fatty acids.
Gut microbiota dysbiosis can influence cognitive functions and psychological well-being by increasing cerebrospinal fluid biomarkers, lipopolysaccharide levels, and amyloid deposition in the brain. These changes are associated with the onset of age-related neurodegenerative diseases, including Alzheimer’s disease.
Gut microbiota dysbiosis can alter a number of metabolic processes, leading to excessive fat accumulation, insulin resistance, and glucose intolerance. These changes are associated with the development of obesity, diabetes, and other metabolic disorders.
This review article finds an interlink between climate change, gut microbiota, and human aging. However, the scientists indicate that studies exploring this interlink are limited. Thus, more studies are required to firmly establish the effects of different aspects of climate change on gut microbiota and the aging process.