A study suggests a diet rich in ultra-processed foods and refined carbohydrates increases the risk of depression and other mental health conditions. The research is in the Journal of the Academy of Nutrition and Dietetics. A nutritional psychologist and dietitian said there is "a tremendous amount of high-quality data linking food to…worsening mental health outcomes". She advised people to cut the amount of sugary and low-fibre food they eat to lessen the chances of getting mood disorders. She said people should limit sugar, refined grains, ultra-processed foods, and alcohol.

The study urged people to increase their intake of high-fibre and fermented foods. It said a plant-based diet was effective in reducing depression. Such a diet includes "omega-3 fatty acids, colourful plants like berries, extra virgin olive oil, leafy greens, and lean sources of protein". These diets are well known to help with depression and anxiety. Related research from a university in Australia corroborated the dietitian's findings. A researcher said fermented, probiotic foods may influence brain-related biology and lead to more positive moods and enhance learning.