Fruits and vegetables can improve an individual's mental health, according to a recent study.

Researchers found that a healthy dietary pattern comprised of fruit, vegetables, legumes, and nuts and low in processed meats, is associated with preventing the onset of depression, Medical News Today reported.

"We wanted to understand what role nutrition plays in mental health, as we believe certain dietary patterns could protect our minds. These diets are all associated with physical health benefits and now we find that they could have a positive effect on our mental health," Almudena Sanchez-Villegas, lead researcher of the study, said in a statement. "The protective role is ascribed to their nutritional properties, where nuts, legumes, fruits and vegetables (sources of omega-3 fatty acids, vitamins and minerals) could reduce the risk of depression."

For the study, researchers collected and analyzed data from more than 15,000 people free of depression at the beginning of the study, The Economic Times reported. Questionnaires to assess dietary intake were completed at the start of the project and again after 10 years. A total of 1,550 participants reported a clinical diagnosis of depression or had used antidepressant drugs after a median follow-up of eight and a half years.

The Alternative Healthy Eating Index-2010 was associated with the greatest reduction of risk of depression but most of the effect could be explained by its similarity with the Mediterranean Diet. Thus, common nutrients and food items such as omega-3 fatty acids, vegetables, fruits, legumes, nuts and moderate alcohol intake present in both patterns (Alternative Healthy Eating Index-2010 and Mediterranean diet) could be responsible for the observed reduced risk in depression associated with a good adherence to the Alternative Healthy Eating Index-2010.

"A threshold effect may exist. The noticeable difference occurs when participants start to follow a healthier diet. Even a moderate adherence to these healthy dietary patterns was associated with an important reduction in the risk of developing depression. However, we saw no extra benefit when participants showed high or very high adherence to the diets," Sanchez-Villegas said. "So, once the threshold is achieved, the reduced risk plateaus even if participants were stricter with their diets and eating more healthily."

The findings are detailed in BMC Medicine.