It seems that eating the right kind of food doesn't only make you healthy, it could make your brain work better.
A report suggests eating healthy food like fruit and veg could help avoid problems later in life like depression.
The report looked at 2,000 people and found that of those with mental health problems, less than half ate fresh fruit or fruit juice every day
However, some nutrition experts don't think enough research has been done into how food affects our brains.
Rebecca Foster, a scientist at the British Nutrition Foundation, added that at the moment it's difficult to work out exactly how the food we eat affects the way we think.
The Mental Health Foundation (MHF) and charity Sustain are behind the research, and they also say that changes to our diets over the last 50 years may have something to do with a rise in mental illness.
They want the government to do more to make healthy food more cheaper and more available.