Exploring gut bacteria’s  influence throughout the body.


A huge diversity of microscopic organisms reside within us and influence our health and bodies in a multitude of ways, and different eating healthier changes the way a person feels. MVHS Senior, Nethra Narasimhan, encompasses this idea.

“The food I eat really changes how I’m feeling, whether it be positively or negatively” Narasimhan says.

However, being aware of the impacts of this vast microbiome and the methods needed to promote beneficial bacteria unlocks new methods of improving health. For instance, incorporating probiotics into peoples’ diet can help maintain overall mental health given the gut microbiome’s impact on the brain.

Gut Bacteria and Our Diet

Our gut bacteria contains trillions of microorganisms in thousands of different species. These species in the gut microbiome include more than just bacteria, and are things that we would normally consider unhealthy, such as parasites, fungi and viruses. However, these species coexist in healthy humans, creating a mutualistic relationship. To ensure that beneficial bacteria thrive and harmful ones don’t, it is important to keep a healthy diet; however, food is only one of the ways to keep a healthy gut microbiome. While these organisms are microscopic, they play an immense role in a person’s health, both inside and outside the gut. Dr. Utpal Durve, who practices medicine in India, discusses how gut bacteria can impact lifestyle.

“There is scientific evidence  that shows that if the gut bacteria is not healthy, you are more likely to have more symptomatic disease, and if you treat them your symptoms will improve, that is irritable bowel syndrome and inflammatory bowel syndrome,” says Dr. Durve.

According to healthline, eating a variety of foods is important because  each type of microorganism requires different nutrients to grow.

“Try to have a diet as diverse as possible,” says Dr. Durve. “So that you have exposure to different types of microbes.” 

Unfortunately, Western diets are heavy in fat and sugar, and are not very diverse. Instead, eating fermented foods, such as yogurt, kimchi, sauerkraut, kombucha, kefir and tempeh are helpful in maintaining and promoting healthy bacteria in the gut. According to Healthline, many fermented foods, especially those which contain the bacteria lactobacilli, are beneficial for one’s health. In addition, some yogurt products have been shown to reduce many harmful bacteria that, for example, cause Irritable Bowel Syndrome or inflammation.

Harvard School of Public Health’s Nutrition Source highlights some foods that benefit the good bacteria in the gut are foods that we, ourselves can’t digest, such as high fiber foods. Such foods are called prebiotics and also include raw garlic, onions, leeks, asparagus, banana and seaweed. 

“[Prebiotics], by themselves, don’t carry any live organisms, but they provide food for the bacteria which live in the large intestine. These foods pass down undigested from the upper gastro-intestinal tract into the large intestine, and they provide food for the healthy bacteria,” says Dr. Durve. 

On the other hand, artificial sweeteners have been shown to be harmful for gut microbiota. In a study conducted by healthline, rats fed artificial sweeteners, showed higher amounts of bacteria, which are connected to various diseases.

Many of these foods are broken down by the bacteria in the gut to produce molecules that allow for more growth of good bacteria or even the prevention of some disease.

Gut bacteria is also known to break down toxic materials and stimulate the immune system. 

“Gut bacteria plays a big role in the development of your immune systems. That’s why in early life what kind of microbes a person is exposed to plays a big role in the immune system,” says Dr. Durve. 

Even further than allergies, an article from Harvard Health and a study published by PLOS ONE convey that the gut microbiome can also indicate the likelihood of getting certain, very serious, diseases such as rheumatoid arthritis, heart disease and even cancer.

Gut Bacteria and Mental Health

Beyond just boosting the immune system, gut bacteria can also affect a person’s mental health. MVHS Junior Akanksha Varansi discusses how food impacts her mental state.

“Usually I find that the food I eat affects my mood and my mental state, not always the other way around,” says Varanasi.

 A study done by Stephanie A. Flowers and Vicki E. Ellingrod, published by accp journals, showed a connection between those that had irritable bowel syndrome and depression. Similarly, this finding is supported by observations from doctors that patients with mental health issues frequently have digestive problems, and vice versa.

According to Discover Magazine, The chemicals that gut bacteria secrete often influence the balance of the chemicals that we produce such as dopamine and serotonin, which are beneficial to moods. Some of the other secreted chemicals play a role in detoxifying the brain and even function as a starting place for some chemicals beneficial to moods such as serotonin.

“When I eat healthier and more nutritious foods, I usually feel better because it gives me more mental energy and I don’t feel as exhausted everyday,” says Varanasi. 

While not it may not be gut bacteria, directly, that impacts mental state, food choices do impact the energy and mood. However, nutritious foods do promote good gut microbiota which do help in the production of chemicals in the brain that promote better moods and energy.

A study  done by Ryan Rieder demonstrated that the bacteria in the gut exert their influence on the brain in multiple ways, including chemical compounds being released into the bloodstream and the vagus nerve, which provides a more direct pathway to the brain. The messages of the vagus nerve are controlled by compounds that are secreted by the bacteria in the gut. This direct pathway of the vagus nerve can prove to be beneficial in dealing mental health because of the ways that gut bacteria influence the brain. However, MV junior, Aris Yang, does not see the difference when eating diets that are more beneficial to good gut microbiota.

“Generally, I do not really see a change in my mental state when eating different kinds of food. When I do eat food containing a lot of sugar, I feel “happy” I guess after I eat because it tastes good. And then later on everything just returns back to normal,” says Yang. “When I eat more high fiber and probiotic carrying food, I don’t notice anything at all. I don’t feel any emotions, or feel more relaxed or stressed.”

This lack of change, or felt change, shows that for a clear improvement to be seen, the shift in diet has to be more long term. However, eating only those healthy foods is not very realistic and unhealthy foods with high sugar and sweeteners are bound to be incorporated in one’s diet. In addition, any changes that are felt by generally eating healthier, might be harder to identify. Narasimhan, generally concurs with not seeing change when eating high fiber foods. 

“My mental health seems to be better, surprisingly, I always feel a little better after eating a block of dark chocolate or a few oreos,” Narasimhan says. “Sometimes, high fiber foods make me really sleepy, so I try to avoid them if I have a lot of work to do.”

Her experiences again show that for a noticeable change to be seen in mental state, a generally good diet that consists of probiotics and prebiotics needs to be maintained for longer periods of time. Short burst of healthy eating may have some impact, but a limited one. Being able to maintain a diet filled mostly with pro- and prebiotics is impossible and little bursts of sugar are needed for energy and for general contentment.

While probiotics and prebiotics may not have a large impact in the short term, a study published by Discover Magazine in 2017, suggests that a diet with a high amount of beneficial bacteria could severely reduce or eliminate depression in more than a third of people. Maintaining a healthy gut microbiome can be done through diet and even probiotics pills. 

One example of probiotics helping in mental health is in a study, published by that same magazine. The stressed mice had an improvement in mood when receiving transplants from healthy mice. They made more bacteria that helps in the production of serotonin, the “happy” hormone. On the other hand, healthy mice had a detrimental change to their mood when receiving transplants from stressed mice. Even though gut bacteria does play a large role in mental health, its maintenance is far from a definitive solution.

Thank Your Gut

The gut microbiome is a fascinating and crucial part of the body. It can help maintain a person’s overall physical health through certain types of food. However, what many people fail to realize is that it branches out of just the digestive system and reaches the immune system, important organs like the heart, and even mental health. 

The presence of bacteria has produced potential treatments for anxiety and depression that have shown significant results in some patients. In this world and environment where mental health is a huge concern, some innovative ways to potentially control some of those issues could prove to be impactful. 

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