The Link Between Food And Mental Health, Explained

Some doctors believe medicine is more like an art than an applied science, treating each patient uniquely and labeling a singular approach as "cookbook medicine." Whereas other doctors argue that advances in medicine and technology have shaped guidelines that should be followed; ignoring these advances is outdated and hurts patients (per Forbes).

Throughout time, patients have endured barbaric treatments from those practicing "medicine." According to The Conversation, procedures like trepanation, an early form of surgery, were used to release demons from the body by drilling a hole in the skull. And bloodletting, where an artery is cut and left to bleed, sometimes for days, was performed to restore balance to the body. Less than 60 years ago, doctors were still performing lobotomies to treat mental health issues. Ice picks were driven into the brain through the eye socket as a form of "psychosurgery," causing patients to be put into a vegetative state or die from the unscientific and painful procedure.

The World Health Organization (WHO) reports that the COVID-19 pandemic has brought a 25% increase in anxiety and depression worldwide, disproportionately affecting women and young people. The pandemic highlighted how ill-prepared countries were to support their citizens facing mental health concerns, spending only 2% of their health budgets on mental health resources. At the same time, WHO estimates one in five people have been struggling with mental health since 2019.

Inexpensive treatments and preventative measures are being researched to make treatments accessible to everyone. Along with talk therapy and medication, a link between food and mental health is being explored.

Psychobiotics: The new science

According to Eater, the link between mental health and food has been explored off and on since the end of the 18th century. Dubbed in 2011 as "psychobiotics," this new science investigates how brain chemistry is affected by the flora in the gut. Psychobiotics include probiotics — the live microorganisms that aid in the digestion of food, fight disease, and produce vitamins — and prebiotics, the undigestible fiber that good bacteria in the gut feed on. Probiotics are found in supplements and fermented food, like yogurt and apple cider vinegar, according to Healthline.

According to the National Center for Complementary and Integrative Health, the use of over-the-counter probiotics has increased over the last two decades, with 4 million (1.6%) American adults in 2012 using the supplements. The International Food Information Council's 2020 Food and Health Survey found that by 2020, 31% of Americans used a probiotic (via Food Insight).

Gastropod, a podcast exploring food through science, touched on psychobiotics and the research that led to important discoveries. Looking at the flora in the gut of mice, researchers found that germ-free mice, without any microbes in their gut, had an exaggerated stress response. This led researchers to question whether microbes were regulating their stress response. Some mice were then fed yogurt, a probiotic, and others a regular diet. Both were placed under stress, and researchers found that the mice who ate yogurt were more relaxed in stressful situations than the other mice. Furthermore, connections in the brain differed between the two sets of mice.

Dopamine and serotonin's connection to the gut

Science, which used to separate mental health from all other medical research, is learning more about the gut-brain axis (or connection), the bidirectional communication between the body's central nervous system and the gut's microbiome. Bidirectional communication means that transmission runs both ways; the brain can affect and change the gut flora, and the microbiome can influence anxiety and depression in the brain. People experience this connection when they feel "butterflies" in their stomachs or need to vomit when nervous.

Most mental health concerns are treated with talk therapy and medications. However, the gut produces 50% of the body's dopamine, which is responsible for rewards and motivation, and 90-95% of serotonin, the happiness hormone. While our bodies naturally produce some serotonin, microbes secrete most of that hormone in our bodies. Cleveland Clinic explains that the brain and gut are connected through the vagus nerve, one of twelve cranial nerves in the body. When the nerve was severed in the mice who received a probiotic, those mice experienced high-stress levels again, reversing the positive effects of the probiotic.

A small study further compared stress levels using human students. Some were fed a diet with fermented foods to feed the bacteria in the gut, providing a favorable environment for bacteria to multiply; other students were fed a regular diet. The results found that students secreted fewer stress hormones when fed fermented foods, just like the mice. However, causality was inconclusive, suggesting further research is needed. Similar results were found with fecal transplants, per Gastropod.

A long-term change in diet

The link between food and mental health is promising, offering another option to treat and prevent depression and anxiety. A high-fiber diet (leafy greens, apples, pears, legumes, nuts, and seeds) and fermented foods (kefir, tempeh, miso, kimchi, and kombucha) have been shown to have positive effects on mental health. According to Healthline, however, 95% of Americans don't consume enough fiber in their diet. The Academy of Nutrition and Dietetics recommends consuming "14 grams of fiber for every 1,000 calories you consume daily, roughly 24 grams of fiber for women and 38 grams for men." The average American only consumes 16.2 grams of fiber.

Since the FDA doesn't regulate over-the-counter probiotics, many manufacturers get away with making claims they can't back up. Unfortunately, the market is flooded with products that won't affect any positive change, especially if you don't eat a high-fiber diet needed to feed the bacteria. Therefore, getting your probiotics from food is more reliable than a supplement. It can be cheaper, too, per Healthline.

Although more research is required to see more medical professionals prescribing a change in your diet to affect mental health, it has other health benefits, including weight loss, lowering cholesterol, reducing gastrointestinal cancer risk, and stabilizing blood sugar levels. Research is promising for preventing and eliminating depression and anxiety without risk or downside if people are willing to change their diet long-term — a small sacrifice for a happier, healthier life.