Carried out by researchers, the new analysis looked at 11 previous studies which had investigated the link between depression and pro-inflammatory diets.
The studies included a total of 101,950 participants age 16 to 72 years old across the USA, Australia, Europe and the Middle East and recorded the presence of depression or depressive symptoms in all participants using self-reports, medical diagnoses and/or antidepressant use.
All participants also completed questionnaires about their diet and were given a score of how inflammatory the diet was.
The findings, published in the journal Clinical Nutrition, showed that in all of the studies, participants who ate a more pro-inflammatory diet, such as those high in cholesterol, saturated fats and carbohydrates, were around 40% more likely to have depression or depressive symptoms.
“These results have tremendous clinical potential for the treatment of depression, and if it holds true, other diseases such as Alzheimer’s which also have an underlying inflammatory component,” said study author Dr. Steven Bradburn.
A US study published earlier this year also found that the DASH diet, which is similar to the Mediterranean diet, and is high in fruits, vegetables and whole grains and encourages nuts and beans, lean meats, fish and poultry rather than saturated fats and sugar, may also reduce the risk of depression. Those who adhered to the diet most showed an 11% lower risk than those who adhered the least.