Promotion of Healthy Aging Through the Nexus of Gut Microbiota and Dietary Phytochemicals
This review highlights the critical connection between dietary phytochemicals, gut microbiota, and healthy aging, focusing on how specific phytochemicals and gut microbiota interact to generate plant-derived microbial metabolites that positively influence healthspan by preventing or delaying age-related diseases.
College of Health researcher(s)
College unit(s)
Abstract
Aging is associated with the decline of tissue and cellular functions, which can promote the development of age-related diseases like cancer, cardiovascular disease, neurodegeneration, and disorders of the musculoskeletal and immune systems. Healthspan is the length of time an individual is in good health and free from chronic diseases and disabilities associated with aging. Two modifiable factors that can influence healthspan, promote healthy aging, and prevent the development of age-related diseases, are diet and microbiota in the gastrointestinal tract (gut microbiota). This review will discuss how dietary phytochemicals and gut microbiota can work in concert to promote a healthy gut and healthy aging. First, an overview is provided of how the gut microbiota influences healthy aging through its impact on gut barrier integrity, immune function, mitochondria function, and oxidative stress. Next, the mechanisms by which phytochemicals effect gut health, inflammation, and nurture a diverse and healthy microbial composition are discussed. Lastly, we discuss how the gut microbiota can directly influence health by producing bioactive metabolites from phytochemicals in food like urolithin A, equol, hesperetin, and sulforaphane. These and other phytochemical-derived microbial metabolites that may promote healthspan are discussed. Importantly, an individual’s capacity to produce health-promoting microbial metabolites from cruciferous vegetables, berries, nuts, citrus, and soy products will be dependent on the specific bacteria present in the individual’s gut.
FAQ on Diet, Gut Microbiota, Phytochemicals, and Healthspan
What is healthspan, and why is it important to consider alongside lifespan?
Healthspan refers to the period of life spent in good health, free from chronic diseases and disabilities associated with aging. While lifespan is simply the length of life, healthspan focuses on the quality of those years. Improving healthspan means not only living longer but also maintaining physical, mental, and social well-being for a greater portion of life, reducing the burden of age-related diseases and enhancing overall quality of life.
How do diet and gut microbiota influence healthy aging and healthspan?
Diet and gut microbiota are two modifiable factors that significantly impact healthy aging. A healthy diet, rich in plant-based foods, provides essential nutrients, fiber, and phytochemicals that promote a balanced gut microbiota. The gut microbiota, in turn, affects gut barrier integrity, immune function, mitochondrial function, and oxidative stress, all of which are linked to age-related diseases. Conversely, unhealthy diets high in sugar and unhealthy fats can lead to gut dysbiosis (imbalance in gut microbiota), contributing to chronic inflammation and accelerating the aging process.
What are phytochemicals, and how do they contribute to gut health and healthspan?
Phytochemicals are non-nutritive bioactive compounds produced by plants, giving them color, flavor, and smell. They exert various beneficial effects on gut health by reducing inflammation, modulating the gut microbiota composition, improving intestinal barrier function, and reducing oxidative stress. Many phytochemicals are poorly absorbed in the upper digestive tract, allowing them to reach the colon where they interact with and are metabolized by the gut microbiota, producing new bioactive microbial metabolites.
What is gut dysbiosis, and how does it relate to aging and age-related diseases?
Gut dysbiosis is an imbalance in the composition and function of the gut microbiota, characterized by reduced microbial diversity and an altered microbial metabolite profile. Age-related dysbiosis is associated with increased intestinal permeability ("leaky gut"), chronic inflammation, impaired immune function, and increased risk of age-related diseases such as cardiovascular disease, neurodegeneration, cancer, and metabolic disorders. Hallmarks of aging, such as mitochondrial dysfunction and cellular senescence, can exacerbate dysbiosis, creating a cycle that accelerates aging.
How do phytochemicals affect inflammation in the gut, and why is this important for healthspan?
Phytochemicals can reduce inflammation in the gut through several mechanisms, including inhibiting the activity of Nuclear Factor Kappa B (NF-κB), a key transcription factor that promotes the expression of pro-inflammatory cytokines. They can also activate Nuclear Factor Erythroid 2-Related Factor 2 (Nrf2), a transcription factor that regulates antioxidant and detoxification genes, reducing oxidative stress. By controlling gut inflammation, phytochemicals help maintain gut barrier integrity and prevent systemic inflammation, which is crucial for preventing age-related diseases and extending healthspan.
How do phytochemicals influence the composition and function of the gut microbiota?
Phytochemicals act as prebiotics, selectively promoting the growth of beneficial bacteria while inhibiting the growth of potentially pathogenic bacteria. This helps to increase microbial diversity and restore balance to the gut microbiota. For example, polyphenols can increase the abundance of beneficial taxa like Lactobacilli and Bifidobacteria, which produce short-chain fatty acids (SCFAs).
What are microbial metabolites, and how do they relate to the health benefits of phytochemicals?
Microbial metabolites are compounds produced by gut bacteria when they metabolize dietary substances, including phytochemicals. Some microbial metabolites, such as urolithins (from ellagitannins in pomegranates and walnuts), equol (from daidzein in soy), and sulforaphane (from glucoraphanin in cruciferous vegetables), have potent health-promoting properties. These metabolites can exert antioxidant, anti-inflammatory, and anti-cancer effects, impacting multiple pathways involved in aging and disease. The ability of an individual to produce these beneficial metabolites depends on the specific composition of their gut microbiota.
What are some examples of specific microbial metabolites derived from phytochemicals, and what health benefits are associated with them?
Examples include:
- Urolithins: Derived from ellagitannins and ellagic acid (found in pomegranates, strawberries, walnuts). Have anti-inflammatory and antioxidant properties, promote healthy muscle function, and may protect against neurodegenerative diseases.
- Equol: Derived from daidzein (found in soybeans and other legumes). Exhibits estrogenic activity and may have cardiovascular and bone health benefits.
- Sulforaphane (SFN): Derived from glucoraphanin (found in cruciferous vegetables like broccoli). Well-known for its cancer chemopreventive properties, and can improve gut barrier integrity and decrease inflammation.
- Hesperetin: Derived from hesperidin (found in citrus fruits). Has been associated with improved barrier functions, reduced inflammation, stimulated SCFA production, and increased beneficial commensal bacteria.