A study suggests ultra-processed foods and refined carbohydrates increase the risk of mental health problems. The research is in a nutrition journal. A dietitian said there was "a tremendous amount of high-quality data linking food to...worsening mental health." She advised people to cut down on sugary and low-fibre food to lower the chance of getting mood disorders. She said people should limit sugar, refined grains, and ultra-processed foods.

The study urged people to eat more high-fibre and fermented foods. It said plant-based diets could reduce depression. Such diets include "omega-3 fatty acids, colourful plants like berries, extra virgin olive oil, leafy greens, and lean sources of protein". These are known to help with depression. Related research from Australia supported the dietitian's findings. It said fermented food may lead to more positive moods and enhance learning.