The condition of your digestive tract has a significant impact on your overall health. Because around 70–80 percent of your immune cells reside in your gut, the composition of your gut microbiome has an impact on the way your immune system works as a whole.
The group of microorganisms (including fungus, bacteria, and viruses) that reside in your digestive tract is referred to as your gut microbiome. The microorganisms that live in your gut, known as the gut microbiota, are subject to change as a result of lifestyle choices such as diet and exercise.
The gut-brain axis allows for direct communication between the digestive tract and the brain, as well as in the other direction. Because of this relationship, your brain has the ability to control the activity of your intestines (such as having anxious diarrhea), and your intestines, in turn, have the ability to control your mood, cognition, and mental health—either positively or adversely.
In addition, having a compromised stomach can make it easier for bacteria and other inflammatory compounds to be absorbed from the digestive tract into the bloodstream. This can bring on infections and inflammation throughout the body, both of which are associated to an increased risk of developing a chronic condition.
Therefore, the food that you put into your digestive tract is extremely important to both your physical and mental health. The following is a list of foods and food groups that promote good functioning of the gut and the microbiome, as well as a list of foods that should be avoided as much as possible for optimal gut health.
Pulses
Pulses are beneficial to digestive health. Pulses are a source of both soluble and insoluble fiber, which fall under the category of non-digestible carbohydrates (NDCs). Pulses also include plant proteins and the antioxidant polyphenols.
Because NDCs play the role of prebiotics, we may say that they provide a food source for the microorganisms in the gut that are advantageous to our health. Anti-inflammatory substances known as short-chain fatty acids (SCFAs) are created when non-digestible carbohydrates (NDCs) are fermented by bacteria in the stomach. In addition to their anti-inflammatory properties, the polyphenols found in pulses can also act as a source of prebiotic fiber.
It has been demonstrated that the anti-inflammatory effect that pulses have on the gastrointestinal tract improves the health of the digestive tract, so enhancing its capacity to act as a barrier between the gastrointestinal tract and the bloodstream.
When the intestinal barrier is strong, only certain helpful things, such as nutrients and water, can pass into the bloodstream. It is possible for dangerous substances to enter your blood circulation if you have an inadequate or weak intestinal barrier. This can lead to systemic or full-body inflammation, which is associated to a number of illnesses and diseases. Particularly important to the process of keeping your gut barrier in good health is the role that SCFAs play.
Pulses include:
- Beans
- Chickpeas
- Dry peas (like split peas and black-eyed peas)
- Lentils
Probiotic Foods
Probiotics are living bacteria that have been demonstrated to increase immunological function, assist reduce the risk of obesity and diabetes, promote general wellbeing, and improve the symptoms of many intestinal illnesses. The consumption of probiotics can alter the environment of the digestive tract in ways that inhibit the growth of pathogenic bacteria while promoting the growth of beneficial bacteria.
Raw sauerkraut is one example of a fermented food that has not been heated to the point of killing probiotics. Numerous studies have demonstrated that the bacteria included in fermented foods are able to withstand the digestive process and make it to the colon, where they are able to assist in the regulation of immune function.
In a study that was conducted in 2021 at Stanford University, researchers evaluated the results of fermented food diets vs high-fiber meals that were randomly administered to a group of 36 healthy people for a period of 10 weeks. Those who consumed fermented foods experienced greater benefits, including positive immune status changes and reductions in levels of 19 inflammatory proteins. One of these proteins, known as interleukin 6, has been linked to conditions such as rheumatoid arthritis, type 2 diabetes, and chronic stress. Those who consumed fermented foods experienced these benefits to a greater extent than those who consumed high amounts of fiber.
The researchers came to the conclusion that the findings of the study indicate that fermented foods may have a powerful impact on immune function and may help treat non-communicable chronic diseases (NCCDs), such as obesity and diabetes, which are both predominantly driven by chronic inflammation.
Probiotic foods may include:
- Fermented vegetables
- Kefir
- Kimchi
- Kombucha
- Miso
- Sauerkraut
- Tempeh
- Yogurt
Prebiotic Foods
The growth of “good” bacterial strains in your gut, such as Bifidobacterium and Lactobacillus, can be encouraged by the use of prebiotics, which also help feed probiotic bacteria. In addition to this, they bring about a change in the pH of the digestive tract, which inhibits the growth of pathogenic bacteria such as Escherichia coli and Clostridium perfringens.
These alterations bring to a decrease in inflammation inside the gastrointestinal tract, and they are thought to stimulate the production of a hormone known as intestinal glucagon-like peptide 2 (GLP2), which is known to strengthen the robustness of the gastrointestinal tract’s lining. In addition, it has been demonstrated that suppressing appetite and improving post-meal management of blood sugar and insulin levels can be accomplished by the fermentation of prebiotic fibers, which results in the synthesis of short-chain fatty acid compounds (SCFAs).It has also been demonstrated that SCFAs can lower inflammation and have a beneficial effect on the management of cholesterol levels.
When compared to the 5.5–20 grams of prebiotics per day that research studies have shown to be beneficial, the normal Western diet, which is often poor in vegetables, fruits, and whole grains, delivers only 1–4 grams of prebiotics per day to its consumers.
Food sources of prebiotics include:
- Asparagus
- Bananas (especially when less ripe)
- Barley
- Chicory
- Garlic
- Jerusalem artichokes
- Leeks
- Onions
- Wheat bran
Polyphenol-Dense Foods
Polyphenols are an antioxidant that can be produced by some plants. During their growth, plants are shielded from harm and disease by these naturally occurring chemicals. In the human body, polyphenols are associated with the protection of both the heart and the brain. In addition, studies have shown that the microbiome of the gut is responsible for the conversion of polyphenols into bioactive compounds. These compounds are then absorbed into the bloodstream and have therapeutic effects within the body.
It is estimated that from five to ten percent of total polyphenols get absorbed into the bloodstream from the small intestine. The remaining 90–95% of the bacteria aggregate in the large intestine, where they exert prebiotic actions that shift the ratio of “good” to “bad” gut microbes in a beneficial direction. The breakdown of polyphenols within the gut has also been connected to the enhancement of the immune system and the prevention of colorectal cancer.
Polyphenol rich foods include:
- Apples
- Artichokes
- Berries
- Broad beans
- Broccoli
- Citrus fruits
- Cocoa
- Coffee
- Onions
- Pears
- Plums
- Tea
Avocados
Consumption of avocados has been related to a number of good health outcomes, including better control of one’s weight and a reduced risk of developing heart disease. According to the findings of a study done in 2021, this fruit is beneficial to intestinal health despite the presence of healthy fats.
The participants in the study were 163 people who were either overweight or obese, and they were randomly assigned to one of two groups for a period of 12 weeks. The avocado was either present or absent at one meal per day (either breakfast, lunch, or dinner) that the participants consumed. Throughout the course of the research, the participants in the study gave samples of their blood, urine, and feces.
Researchers discovered that people who ate avocados acquired a bigger abundance of gut bacteria that are responsible for breaking down fiber and producing SCFAs that are helpful. People who did not consume the avocado meals did not grow the same rich diversity of beneficial gut microorganisms as those who did consume the avocado meals. And despite the fact that those in the avocado group consumed a few extra calories, they passed more fat in their stools, which indicates that their bodies were able to retain less of the fat that was taken in by their digestive systems. The researchers claim that this is the first study to investigate the effects of avocado consumption on human gut microbiota without subjecting the participants to a caloric restriction. As a result, they were able to rule out the possibility that changes in calorie intake had a role in the observed shifts.
Gut-Healthy Foods to Limit
It has been established that certain foods have a detrimental effect on the health of the gut and the bacteria that live there. To get the best possible gut health, limit or avoid these items.
Red Meat
According to research, the amino acid known as L-carnitine, which is found in red meat, is converted by the microorganisms in the gut into a molecule known as trimethylamine-N-oxide (TMAO). This chemical has been associated to the hardening of the arteries and increased risk factors for heart disease.16 Consumption of processed red meat, such as bacon, sausage, and pepperoni, may also lead to an increase in the quantities of microorganisms in the gut, which in turn leads to an increase in inflammation and an increased risk of colorectal cancer.
Ultra-Processed Foods
Foods that are considered to be ultra-processed are those that have been industrially produced and are either ready-to-eat or ready-to-heat formulations. These foods contain food additives but little or no whole foods. For instance, soft beverages, fast food, chicken nuggets, hot dogs, and sweets all fall into this category. Consuming large amounts of these foods is linked to an increased risk of developing cardiovascular disease as well as obesity.
When compared to diets that are high in minimally processed plant foods, ultra-processed foods were shown to have a lower type and range of beneficial gut bacteria, according to a review of research conducted in 2021. This shift increases the permeability of the stomach, which in turn causes inflammation in the gut. As was mentioned before, these alterations in the gut make it possible for compounds to be absorbed into the bloodstream. These substances can induce inflammation throughout the body and raise the chance of developing a variety of diseases, including obesity, dementia, and Alzheimer’s disease.
Alcohol
According to a number of studies, drinking alcohol regularly has a major impact on the microbial population that lives in the gut. Alcohol consumption leads to a reduction in the number of good microbes, an increase in the number of bad, pro-inflammatory microbes, and an increased permeability of the gut lining, which makes it easier for pathogenic germs to be absorbed into the circulation.
Artificial Sweeteners
The use of artificial sweeteners has been related to an increased risk of obesity and type 2 diabetes, and the effects may begin in the gut. This is despite the fact that artificial sweeteners contain neither sugar nor calories. When healthy mice had the gut microbiota extracted from hosts that consumed reduced calorie sweeteners put into them, the healthy mice had an altered glucose tolerance.23 According to the findings of other studies, sugar replacements may alter the microbial composition of the gut, leading to a decrease in the generation of SCFAs that are beneficial and an increase in inflammation.
Summary
Foods that are good for the gut improve immune function, the type and number of beneficial gut microbes, the growth of harmful bacteria, the production of anti-inflammatory compounds like SCFAs, the growth of beneficial gut microbes, and the integrity of the gut wall, which helps keep harmful compounds out of the bloodstream.
Some meals have the opposite impact in the stomach, which can result in impaired immune function, digestive ailments, and even an increased chance of developing chronic diseases.
