How Gut Bacteria Changes With the Seasons

It’s officially pumpkin spice latte season, but what does that mean for the trillions of microorganisms living in your gut? Surprisingly, a lot. The composition of your gut microbiome can change with the seasons. Just in time for the fall equinox, let’s talk about the fascinating connection between the gut microbiome and the changing seasons. 

The gut microbiome

Before delving into the seasonal changes, let's briefly understand the gut microbiome's composition and significance. The gut microbiome is primarily composed of bacteria, but it also includes viruses, fungi, and other microorganisms. These microorganisms form a complex, symbiotic relationship with our bodies, aiding in digestion, synthesizing vitamins, and training our immune systems. While we usually think of bacteria as a bad thing, in the gut, it can actually be quite beneficial. There are good bacteria and bad bacteria, and the idea is to have a healthy balance.

Your seasonal gut

Research has revealed that the gut microbiome is not a static entity but instead a dynamic ecosystem that adapts to various environmental factors, including diet, lifestyle, and yes, the seasons. Here's how the seasons can impact your gut bacteria…


As temperatures drop, our gut microbiota undergoes subtle but significant changes. During the colder months, the diversity of gut bacteria tends to decrease. This means that there are fewer types of bacteria living in the gut during winter than in the warmer months. This may be because we tend to eat heartier, starchier foods in the colder months, and less fiber-rich fruits and vegetables. Foods rich in fiber and polyphenols support the growth of beneficial bacteria such as Akkermansia muciniphila, a keystone strain for gut health.

This reduction in microbial diversity may be an evolutionary adaptation to conserve energy. In winter, our bodies may prioritize energy storage and insulation against the cold. Consequently, the gut microbiota may shift to favor bacteria that are efficient at extracting energy from the food we consume.


As the world awakens from its winter slumber, so does our gut microbiota. With the arrival of spring, microbial diversity in the gut tends to increase. This surge in diversity may be linked to the abundance of fresh fruits and vegetables available during this season. These foods are rich in dietary fiber and provide nourishment for a wider range of microbial species.

Furthermore, the longer days and increased exposure to sunlight in spring can positively impact gut health. Sun exposure is associated with the production of vitamin D, which has been linked to a healthier gut microbiota.


Summer is a time of travel for many, weekend getaways, road trips, and trans-continental flights. Interestingly, these journeys can also influence our gut microbiota. When we travel, we are exposed to new environments, foods, and microbes. These novel experiences can introduce diverse bacteria into our guts, temporarily altering the microbial composition.

In addition, traveling can affect our circadian rhythm. Influenced by daylight hours, our circadian rhythm plays a role in regulating gut bacteria. Seasonal shifts in light exposure can impact this rhythm, potentially affecting the gut microbiome's composition.

Additionally, the increased sun exposure during summer can further promote the growth of certain beneficial bacteria. Vitamin D production continues to play a role in maintaining gut health.


As autumn approaches and the days grow shorter, the gut microbiota shifts yet again. It appears that the gut prepares for the colder months by adjusting its composition. Certain bacteria associated with carbohydrate metabolism and immune function may become more prevalent, perhaps in anticipation of the dietary changes that often accompany the fall harvest.

In addition, seasonal changes in temperature often lead to variations in physical activity. Increased outdoor activities during the warmer months may expose you to different environmental microbes, potentially diversifying the gut microbiome, while decreased physical activity in the fall and coming winter can inhibit bacterial exposure.

Our gut microbiota is a remarkable and adaptable community of microorganisms. It responds to the changing seasons in ways that reflect both evolutionary adaptations and environmental influences. From conserving energy in the winter to embracing diversity in the spring, our gut bacteria's seasonality mirrors the ebb and flow of the natural world.

Understanding how gut bacteria change with the seasons offers valuable insights into maintaining gut health year-round. It underscores the importance of a balanced diet, exposure to sunlight, probiotic supplementation, and even travel experiences in shaping the microbial composition of our guts.

Cheers to a healthy gut…and a happy fall!

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