The question if diet can improve mental health recently received a lot more attention from researchers. Intervention studies are still limited, as one study in 2019 mentioned, "To our knowledge, there is only one other randomized controlled trial of a diet intervention in young adults, which included mood as an outcome." (1) But the good news is that many other kinds of studies have shed some light on this matter.
How can the food that we eat affect our mental health? It is because of our gut. There is a "highway" between the gut and the brain called the gut-brain axis. Our mental state can affect our gut, but the state of our gut can also affect our mental state too! Kinda crazy right?
Looking at 3486 participants in the UK, researchers saw that people who eat "whole food" are at 26% less risk of getting depressive symptoms than those who eat "processed foods" are at 58% more risk. (2) Another evidence from the Adventist Health Study saw that "vegetarians reported significantly less negative emotion than omnivores" despite a lower intake of omega 3 in the form of DHA and EPA but higher intake in the form of ALA. (3)
What is the mechanism behind it? Our gut bacteria, which are a lot more than our human cells in number, produce tons of neurochemicals that "regulate basic physiological processes as well as mental processes such as learning, memory, and mood. For example, gut bacteria manufacture about 95 percent of the body's supply of serotonin, which influences both mood and GI (Gastrointestinal) activity." (4)
Our gut will produce these good and happy hormones when we feed them plant foods that contain fiber! (5) From complex carbohydrates, legumes, fruits, vegetables, nuts, and seeds help provide the fiber we need to improve our mental health!
Another possibility of a plant-based diet can improve mental health simply because it can improve the person's overall health (6), for example, from diabetes, weight loss, and heart disease. Of course, someone would be happy if they can reverse the disease they have with a plant-based diet.
We should not forget that other aspects of life, such as exercising, sleep, social relationships, can also affect our mental health. But diet is one of them. Supporting your mental health with a plant-based diet is something you could do every day whenever you eat. Stay plant-based and experience better mental health!