Scientists from Shahrekord University of Medical Sciences report that following a vegetarian diet may be linked to a higher risk of depression.
Depression is more than occasional sadness. When low mood lasts for a long time and impacts daily functioning, it may be diagnosed as depression.
Its exact cause is still unclear, but experts believe it results from a combination of genetic, biological, environmental, and psychological factors.
About 1 in 6 adults will experience depression at some point in their lives, and it affects roughly 16 million adults in the United States each year.
Previous studies have explored whether vegetarian diets influence depression risk, but inconsistent findings have made it difficult to draw firm conclusions. In this new research, scientists reviewed published studies that compared depression levels and depression risk in vegetarians versus non-vegetarians.
The analysis found that people who followed a vegetarian diet had a 53% higher risk of depression compared to omnivores. However, this increased risk was not consistently seen across all studies.
The results varied based on the type of vegetarian diet and the country in which the study was conducted.
For example, studies that looked at semi-vegetarian (flexitarian) diets—plant-based diets that allow occasional meat—showed a positive link between this eating pattern and depression. Studies carried out in Europe and the United States also tended to show a stronger association between vegetarian diets and depression risk.
Interestingly, when researchers compared the average depression scores of vegetarians and non-vegetarians, they found no significant difference. This suggests that while some studies report increased risk, the overall emotional wellbeing of vegetarians and non-vegetarians may not differ greatly.
The authors caution that the findings are not robust, meaning they should be interpreted carefully. More high-quality studies are needed to better understand whether a vegetarian diet contributes to depression or whether other factors—such as social, cultural, or nutritional differences—play a role.
The study was published in Nutrition Reviews and led by Siavash Fazelian and colleagues.
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