The Microbiome and Aging: How Our Gut Bacteria Changes as We Get Older

The human body is a complex ecosystem that houses trillions of microorganisms, collectively known as the microbiome. The microbiome plays a crucial role in maintaining our health and wellbeing, influencing everything from our immune system to our mental health. While the composition of the microbiome is unique to each individual, there are certain patterns that emerge as we age. In this article, we’ll explore how our gut bacteria changes as we get older, and what impact this has on our health.

The Gut Microbiome: A Brief Overview

The gut microbiome refers to the collection of microorganisms that live in our intestines. These microorganisms include bacteria, viruses, fungi, and other microbes. The gut microbiome is incredibly diverse, with over 1,000 different species of bacteria residing in the human gut alone.

The gut microbiome plays a crucial role in our overall health. It helps to break down food and extract nutrients, regulates our immune system, and even produces certain vitamins and neurotransmitters. When the microbiome is disrupted, it can lead to a wide range of health problems, including digestive disorders, autoimmune diseases, and mental health issues.

The Microbiome and Aging

As we age, our gut microbiome undergoes significant changes. One of the most notable changes is a decrease in microbial diversity. Studies have shown that older adults have less diverse gut microbiomes than younger adults, with a smaller number of bacterial species present in the gut.

This reduction in microbial diversity has been linked to a number of health problems that are common in older adults. For example, a less diverse microbiome has been linked to an increased risk of inflammatory bowel disease, as well as a weakened immune system.

In addition to a reduction in microbial diversity, the gut microbiome also undergoes changes in composition as we age. Specifically, there is an increase in the prevalence of certain bacterial species, such as Firmicutes and Proteobacteria, and a decrease in others, such as Bacteroidetes. This shift in bacterial composition has been linked to a number of age-related health problems, including obesity and type 2 diabetes.

Factors That Influence the Microbiome and Aging

There are a number of factors that can influence how our gut microbiome changes as we age. One of the most important ones is diet. Studies have shown that a diet high in fiber and plant-based foods can promote a more diverse gut microbiome, while a diet high in processed foods and sugar can lead to a less diverse microbiome.

Other factors that can influence the microbiome include medication use, stress, and lifestyle factors such as smoking and alcohol consumption. Certain medical conditions, such as diabetes and inflammatory bowel disease, can also have a significant impact on the gut microbiome.

The Importance of a Healthy Microbiome

Maintaining a healthy microbiome is essential for overall health and wellbeing, especially as we age. A diverse and balanced microbiome can help to regulate the immune system, improve digestion, and even protect against age-related cognitive decline.

There are a number of steps that individuals can take to promote a healthy microbiome. These include eating a diet rich in fiber and plant-based foods, avoiding processed foods and sugar, and taking probiotics or prebiotics to support gut health. Managing stress, getting regular exercise, and avoiding smoking and excessive alcohol consumption can also help to promote a healthy microbiome.


The gut microbiome plays a crucial role in our overall health and wellbeing, and undergoes significant changes as we age. While the exact reasons for these changes are not yet fully understood, there are a number of factors that can influence the composition and diversity of the gut microbiome. By taking steps to promote a healthy microbiome, individuals can help to protect against a wide range of age-related health problems and improve their overall quality of life.

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Dr. Pedram Shojai

NY Times Best Selling author and film maker. Taoist Abbot and Qigong master. Husband and dad. I’m here to help you find your way and be healthy and happy. I don’t want to be your guru…just someone who’ll help point the way. If you’re looking for a real person who’s done the work, I’m your guy. I can light the path and walk along it with you but can’t walk for you.