Gut Microbes Play a Key Role in Depression Symptoms.

In 2025, Xiangyan Zhou and a team from Huazhong University of Science and Technology in China reviewed studies on how gut microbes affect depression. They explored the gut-brain axis, a two-way connection between your belly and brain, showing how gut bugs impact mood and mental health. Depression affects about 21% of people worldwide, that’s around 280 million people, and family history boosts risk by 37-48%.

The review found that an imbalance in gut microbes can worsen depression by disrupting short-chain fats that help the brain (dropping by up to 50%), nerve signals through the vagus nerve, stress hormones from the HPA axis (increasing cortisol by 20-30%), and swelling from immune responses. Good gut bacteria might protect against depression, with some studies showing a 15-25% lower risk in people with healthy guts.

Eat foods like yogurt or sauerkraut with good bacteria to help your gut and maybe boost your mood.