Based on a study involving, 15,093 people researchers have established for the first time that there is an association between healthy dietary patterns and risk of depression. Diet rich in low processed meats, fruit, vegetables, legumes, and nuts helps fend off depression and to establish this researchers compared three diets including the Mediterranean diet, the Pro-vegetarian Dietary Pattern and Alternative Healthy Eating Index-2010.
To keep a track of how healthy their diet was, participants used a scoring system to measure their adherence to the selected diet. In the study, meat and sweets were negatively scored, while nuts, fruits and vegetables were positively scored.
Lead researcher, Almudena Sanchez-Villegas, University of Las Palmas de Gran Canaria, says that their study has shown that all those food items that have been long been associate with physical health benefits also have a positive effect on our mental health.
“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.”
All the participants who took part in the study were free of depression at the beginning of the study. The participants are a part of the SUN (Seguimiento Universidad de Navarra) Project, a cohort study started on 21st December 1999. The cohort has been used to identify dietary and lifestyle determinants of various conditions, including diabetes, obesity and depression.
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 8.5 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.
Almudena Sanchez-Villegas says, “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.
So, once the threshold is achieved, the reduced risk plateaus even if participants were stricter with their diets and eating more healthily. This dose-response pattern is compatible with the hypothesis that suboptimal intake of some nutrients (mainly located in low adherence levels) may represent a risk factor for future depression.”
A limitation of this study was that the results are based on self-reported dietary intake and a self-reported clinical diagnosis of depression. More research is needed to predict the role of nutrient intake for neurophysiological requirements and identify whether it is minerals and vitamins or proteins and carbohydrates that cause depression.