How does Ramadan fasting reorganize the “bacteria kingdom” in your gut?

Results vary between those who are certain and those who are skeptical about the actual effect of Ramadan fasting on the distribution of microorganisms that colonize our digestive system. While some acknowledged the improvement the body gained after fasting due to the revival of beneficial bacteria specifically, others went further and suggested that other factors such as the type of food, the timing of meals, and their size play a role in the number of microorganisms that are naturally present in our intestines (known as the Microbiota).

What is the relationship between the microbiota and our overall health?

The benefits of fasting on the body’s health are still being revealed day by day. While some studies have confirmed that Ramadan fasting has a positive effect on heart health, boosts metabolism, raises cell vitality, and rids the body of accumulated pathogens and damaged cells by stimulating autophagy, other studies have indicated that fasting may also regulate the microbiota in our intestines, thus improving our health.

The bacteria in our intestines are a vital resource associated with various functions that promote the body’s health and play a key role in strengthening our immune barrier to fight various diseases. They are also associated with immune, metabolic, and neurological functions, and are related to the endocrine glands responsible for producing hormones. Therefore, many people who suffer from various health problems are looking for natural ways to help them restore the diverse and enriching composition of beneficial bacteria that live in our gut.

The intestines contain millions, even trillions, of microorganisms that grow and multiply within them to perform a range of pivotal and important functions for the body’s health. For example, they stand as an immune shield against the proliferation of harmful bacteria to ensure the required biological harmony there. They also contribute to the development and maturation of the immune system, in addition to their tasks in digesting food molecules to supply the body with the energy and other things it needs.

Bacteria constitute approximately 90% of the total microorganisms that live in the intestines, specifically within two main phyla: Bacteroidetes and Firmicutes. They are often able to maintain the normal ratio of their abundance in the intestines due to their flexibility and ability to reproduce and restore balance again without significant change, despite being constantly exposed to various factors, such as drinking water rich in chlorine, food additives, antibiotics, and various pollutants that we may ingest with food particles, such as pesticides previously used on agricultural crops, heavy metals, and others. This necessitates following methods that preserve or even restore the vital communities of bacteria that live inside us and that we may lose unintentionally.

Is fasting alone sufficient to boost the gut microbiota?

A scientific review published in the journal Current Research in Biotechnology in 2025 by a group of researchers indicated the amazing ability of fasting to increase the diversity of the microbiota (specifically beneficial bacteria) in the intestines, and to promote the growth of the bacteria present therein, resulting in a remarkable improvement in the body’s health through its effect on metabolic indicators, including lowering high blood pressure, regulating glucose and fat levels, controlling body weight, and reducing inflammation.

In another study led by a group of researchers from the University of Chile, and published in the journal Nutrients in 2020, which included 12 healthy people who fasted during Ramadan, a group of researchers tried to find out the effect of fasting on the bacteria that live naturally in the intestines, and the extent to which this is reflected in the health of the body compared before and after Ramadan, especially the ratio of bacteria from Bacteroides to Firmicutes, which make up the largest part of the microorganisms in the intestines.

The results indicated a decrease in the percentage of certain types of beneficial bacteria towards the end of Ramadan. After analysis, it was found that the type of food consumed was one of the most important causes of these changes. Thus, according to this study, fasting alone is not sufficient to control the bacterial presence in the intestines, and it is necessary to select types of food to obtain the greatest benefit from fasting.

Numerous studies confirm that the type, quantity, and timing of meals during Ramadan rapidly affect metabolism and the balance of gut bacteria.

For example, the number of Faecalicatena bacteria decreased with a decrease in fiber consumption, while the number of butyrate-producing Coprococcus bacteria increased with the consumption of plant proteins and foods rich in complex sugars such as mushrooms, grains, and seaweed, thus changing the distribution of bacteria in the gut.

In a systematic review published in 2024 by a group of researchers from the University of Eastern Finland and others, which aimed to assess the effect of fasting on the microbiota in the human gut, the results were mixed and indicated that fasting changes the bacterial diversity in the gut. At the end of the fasting period (after 29 or 30 days), the growth rate of certain types may increase, while other types may decrease.

But this difference quickly returns to its previous state after Ramadan ends, which means that it is a temporary change. This review also confirmed what the previous study concluded, that the diversity of the gut microbiota depends on different factors, most notably the diet followed after breaking the daily fast.

Also, a group of researchers from prestigious research centers in Germany were able to reach a positive conclusion that periodic fasting followed by following a specific diet (they relied on a special diet for patients with high blood pressure) enhances the balance of intestinal bacteria, which in turn affects the immune response, so patients feel better as their blood pressure decreases and returns to almost normal levels for longer periods. These positive results came exclusively after fasting followed by the diet, and not the diet alone.

Between food and fasting, what is required?

Studies recommend further research to verify the actual and confirmed relationship between fasting and the microbiota, but until then, the golden recommendation to make the most of fasting and reap the greatest health benefits is to consider the components of the food dishes that line our tables. Fruits and vegetables, along with legumes, whole grains, nuts, and seeds, are among the foods recommended by studies due to their ability to support the growth of beneficial bacteria in the intestines and maintain their balance.