Diets high in refined sugar and other added sugars negatively impact microbes in your gut, according to a review published July 2019 in Nutrients. An earlier article, published in 2017 in Scientific Reports, found a link between sugar intake and symptoms of depression. Foods to focus on, Ghannoum says, include “good proteins from plants, healthy oil such as coconut oil or extra-virgin olive oil, and fruits and vegetables.” More specifically, an anti-inflammatory diet (one full of fruits, vegetables, whole grains, and healthy fats, and with fewer animal products, processed packaged foods, and other foods associated with inflammation in the body) can help reduce depressive symptoms, according to a meta-analysis published in Molecular Psychiatry in July 2019.

It doesn’t matter whether you walk, run, cycle, or engage in another aerobic activity: Regular endurance exercise enhances gut health. “There is a beneficial association of exercising with the microbiome,” Ghannoum confirms. “It will increase the diversity, which means you have a lot of different microorganisms there.” A diverse microbiome is good for your health, whereas a less diverse microbiome is linked to digestive health issues, per research published in March 2016 in Frontiers in Microbiology.

How much exercise is enough to reap that benefit? A study published in June 2021 in Frontiers in Nutrition suggests that moderate-intensity endurance exercise is best for promoting a healthy gut microbiome. Exercising 30 minutes a day, even walking, will be very good, in fact, regular exercise could deliver a better mood right away.

You can easily add probiotics (the live “good” bacteria that flourish in your gut) and fiber — a type of carbohydrate that feeds the good bacteria to your diet by eating certain foods or taking probiotics, affect the composition of microorganisms in the gut, which in turn may lower the risk of mood disorders, among other potential health benefits. That said, it’s not yet clear whether probiotics can help treat an existing mood disorder, so more research is needed before they can be recommended specifically to manage depressive symptoms.

If you take antidepressants or other medications, be sure to talk to your doctor before trying a probiotic supplement, to avoid potential drug interactions.