Studies have shown that various age-related diseases are tied to the composition and diversity of an individual’s gut microbiota.miniseries/iStockPhoto / Getty Images
The role diet plays in aging has received considerable attention in recent years.
Healthy dietary patterns such as the Mediterranean and DASH diets, for example, are thought to slow the aging process by reducing inflammation and oxidative stress in the body.
At the same time, studies have shown that the composition and diversity of the gut microbiota – the community of trillions of microbes that reside in our large intestine – are closely tied to various age-related diseases such as cardiovascular disease, Type 2 diabetes and dementia.
The terms microbiota and microbiome are often used interchangeably, but there’s a subtle difference. Microbiota refers to the collection of gut microbes themselves, while microbiome refers to the microbiota plus their genetic material and the environment they live in.
Now, a new study suggests that eating specific foods can alter the gut microbiota in a direction that delays aging.
Here’s a breakdown of the research and its important findings, plus which foods to eat more of to bolster the healthy-aging potential of your gut microbiota.
The dietary index for gut microbiota
The unique dietary index for gut microbiota (DI-GM), recently proposed in 2024, is a diet assessment tool that measures diet quality scores associated with maintaining a healthy gut microbiota.
The DI-GM is made up of 14 foods and nutrients that have been linked to gut microbiota health.
These include 10 foods and nutrients research has shown are beneficial to gut microbiota: avocado, broccoli, chickpeas, coffee, cranberries, fermented dairy products (yogurt, kefir, buttermilk, aged cheese), fibre, green tea, soy foods and whole grains.
These diet components help maintain a healthy gut microbiota by increasing the diversity of microbes in the gut, enriching the types of health-promoting gut microbes or decreasing potential disease-causing microbes.
The DI-GM also contains four unfavourable components that have opposite detrimental effects on the gut microbiota – red meat, processed meat, refined grains and a high-fat diet (defined as containing at least 40 per cent of calories from fat).
DI-GM scores range from 0 to 14; a higher score indicates a healthier gut microbiota.
About the latest research
The study, published July 12 in the Journal of Health, Population and Nutrition, is the first to investigate the association between biological aging and diet, using the DI-GM, in a nationally representative population.
To do so, researchers analyzed data from 29,435 adults, average age 50, who participated in the annual U.S. National Health and Nutrition Examination Survey from 1999 to 2018.
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Biological aging was estimated using 10 aging-related indicators including blood levels of creatine (a measure of kidney function), glucose and C-reactive protein (an inflammatory marker), as well as red and white blood cell measures and chronological age.
Higher DI-GM scores were significantly associated with a lower risk of biological aging and accelerated biological aging. Accelerated biological aging means a person’s biological processes are aging faster than their chronological age.
To arrive at these findings, the researchers accounted for many other factors that influence aging such as gender, race, body mass index, education level, smoking status, alcohol intake, physical activity, cardiovascular disease, diabetes, high cholesterol and hypertension.
The findings also revealed that increasing the intake of gut microbiota-beneficial foods was more important than simply eating fewer gut microbiota-detrimental foods.
Each one-point increase in the DI-GM score was tied to a 7-per-cent reduced risk of accelerated biological aging, suggesting that the benefits of dietary patterns on the gut microbiota play an important role in delaying biological aging.
Strengths, limitations
The study is notable for its use of a large-scale and nationally representable sample with multiple years of diet and health measures.
It also used an innovative diet quality assessment tool based on the relationship between diet and gut microbiota composition.
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A limitation is that dietary data was collected by asking participants to report food consumption in the previous 24 hours; errors may have occurred owing to forgetting some foods or beverages.
As well, because the NHANES data sets did not include gut microbiota measurements, the association between participants’ DI-GM scores and actual gut microbiota diversity could not be verified.
Diet, gut microbes and biological aging
Even so, there are plausible ways in which adjusting your diet to improve your gut microbiota may help delay aging.
Dietary patterns with high DI-GM scores are plentiful in fibre, prebiotics (e.g., whole grains, chickpeas, soybeans, kefir, avocado) and polyphenols (e.g., green tea, coffee, cranberries), compounds that promote the growth of Bifidobacterium and Lactobacillus.
These beneficial bacteria produce short chain fatty acids which have anti-inflammatory properties, provide energy for intestinal cells, support a strong intestinal barrier, regulate immune function and influence metabolism.
Conversely, diets with low DI-GM scores, high in red and processed meats and refined grains, can increase the proportion of harmful gut bacteria that produce endotoxins. These toxins can pass into the bloodstream and trigger low-grade chronic inflammation, believed to be a significant contributor to the aging process.
Leslie Beck, a Toronto-based private practice dietitian, is director of food and nutrition at Medcan. Follow her on X @LeslieBeckRD
