Summarise the content of the article (5 lines) Scientists have cast new light on the effects our diet has on our mental health. Researchers say what we eat affects and alters our brain chemistry up until the age of 30. They say this explains why older adults are more emotionally stable and resilient than under-30s. The research was conducted by a team led by Lina Begdache, a professor of health and wellness studies. Researchers said that while the link between our diet and diabetes, heart disease and obesity is well established, there is a paucity of research on the influence our dietary intake has on mental health. The researchers also suggested that mental well-being stimulated healthy eating, healthy practices, and exercising. Professor Begdache found that adults under 30 who ate fast food more than three times a week scored higher on levels of mental distress, anxiety and depression. She said that for adults over 30, the study found that eating less carbohydrates and more fruit reduced anxiety and depression. Begdache pointed to research showing how a Mediterranean diet was as good for our brain as for our body. She said: "It has all the components that are important for the healthy structure of the brain."