A photo of a Mediterranean bowl with grilled vegetables, representing food that may be used for treating depression.
Photo by Edgar Castrejon on Unsplash

According to Mindful, the ENS "arises from the same tissues as our central nervous system (CNS) during fetal development." If you're in need of a quick refresher on human biology: the central nervous system is comprised of the brain and spinal cord.

Being that the two systems come from the same tissues, it's no surprise that the body processes information with both.

As we go through life, events such as illness, antibiotic treatment and changes in diet affect the balance of our gut microbiome.

Regulation of the gut microbiota and ENS with healthy choices related to diet and environment can be a useful tool for preventing and treating depression.

“Gut microbes are more in control of the gut-brain communication than we believe our conscious brain is,” said Dr. Gemma Newman, family physician, “There are ten times more signals going from the gut to the brain as there are going from the brain to the gut.”

This intricate connection is known as the gut-brain axis. Thick nerve cables carry information from the brain to the GI tract and vice versa. These nerve cables are then facilitated with biological communication signals carried through the bloodstream.

So how might those communication signals in our body influence the way we feel?

One of our body's better known chemicals, serotonin, is often referred to as "the happy chemical." While it is commonly associated with pleasure and well-being, it also plays a critical role in our sleep patterns and appetite. About 90% of the body’s serotonin is found in the gut - making it the body's primary home for serotonin.

“If there is inflammation or bad bacteria in the gut, it will send signals to your brain all day long that your body is in distress,” said Jaclyn Renee, HHC and digestive specialist.

In the average lifespan, 60 tons of food will pass through the human GI tract along with microorganisms that are found in the environment. These microorganisms can pose a large threat to our gut health. The goal is to maintain a healthy balance of bacteria in the gut by eating a diversity of fruits and vegetables with a high dose of fiber. Having a majority plant-based diet is optimal - the more plants the better.

Tryptophan is an amino acid, mainly found in nuts and seeds, that acts as a precursor to serotonin - influencing the rate at which it is synthesized in the body.

Alternatively, proteins within meat can inhibit the absorption of tryptophan in the brain.

By consuming a majority of plant-based foods, the subsequently higher levels of tryptophan in our bodies will boost serotonin levels and our mood.

While higher tryptophan levels have been scientifically linked to positive feelings, it's important to note that there is no one diet that works for everyone.

"Plant-based does not mean attaching yourself to a label like “vegan” or “vegetarian," heeds Dr. Newman. "People still eat junk food on a vegan diet. Or you could have had courses of antibiotics and then your guts going to be trouble and you’re not going to feel the benefits of being vegan." He added, "There are many emotions that are associated with what we eat - family traditions, childhood comforts, fitting in with our peers or our friends. We shouldn’t live too restrictively.”

Dr. Newman and Renee both suggest consuming organic produce if it’s affordable. Pesticides are antibacterial and antifungal and can deplete gut microbes.

“Our crops are overloaded with pesticides and our packaged food is full of preservatives, dyes and synthetic sugars,” Renee said. “These all affect the body and brain and can definitely play a role in many mental health issues.”

In a 2017 study published to BMC Medicine termed the SMILES trial, researchers recruited participants who reported symptoms of depression. The participants were randomly placed in one of two groups - a controlled group and a dietary health group. The second group received a dietary intervention, which involved meeting with a dietitian and consuming a Mediterranean diet of fresh fruits, vegetables, whole grains, legumes, nuts, extra virgin olive oil and fish.

A third of participants met criteria for remission of major depression.

Another study of 35 university employees revealed that consumers of fast food, compared to those who eat little or none, are 51% more likely to develop depression, and the more you consume, the greater the risk is.

This depression-inducing dietary pattern appears to be associated with high glycemic carbohydrates. Many participants reported feeling down the day after eating sugary foods. However, the researchers found eating high-fiber foods such as whole grains, whole fruits, and vegetables lowered their odds.

A photo of a black bean and avocado taco platter, representing food that may be used for treating depression.
Photo by Edgar Castrejon on Unsplash

“There are so many different environmental factors involved, all of which could bring your normal microbe population to its knees,” Dr. Newman said.

“If your gut microbes are depleted, say from a strong course of antibiotics or from eating a lot of factory farm meat that contains a lot of antibiotics, or even from having alcohol, then you’ve got a problem because you’re not able to produce enough of these feel-good hormones.”

Several environmental factors, aside from diet, shape the microbiota including geographical location, surgery, smoking and the quality of one's living arrangements. Antibiotic treatment dramatically disrupts both short- and long-term microbial balance, including decreases in the richness and diversity of the community.

Antibiotics shape the physiology and gene expression of the active human gut microbiome. That not only includes prescription antibiotics but the antibiotics we consume through eating factory farm meat that has been treated with it.

Renee recommends to all her patients that experience gut dysfunction and depression to stay on a plant-based protocol for six to 12 months to heal the damage that has been done. Her protocol also immediately cuts sugar, alcohol, gluten and caffeine - all factors that disrupt the microbiome.

“If you stay consistent with your nutrition and self-care you will start feeling better quickly. Healing is not linear,” Renee said. “Sometimes you take two steps forward, sometimes two steps back.”

Several authors suggest applying this new research and information to the future of treating depression. Medical professionals may begin to prescribe plant-based diets more often.

Using microorganisms and probiotics as a new group of antidepressant drugs named “psycho-microbiotics” for the treatment of depression and other psychiatric disorders may be in our future as well.