Many studies have examined the relationship between diet and depression. The studies largely look at individual nutrients rather than dietary patterns as a whole. In a recent study of 3485 men and women in England, a comparison was made between rates of depression of individuals eating a “processed food” diet and those eating a “whole food” diet.

The “processed food” diet was heavily loaded with sweetened desserts, fried foods, processed meat, refined grains, and high-fat dairy products. The “whole food” diet consisted of a liberal intake of vegetables, fruits and fish. Diets were determined using a 127-item food frequency questionnaire. Those with a high intake of processed foods were 1.58 times as likely to experience depression compared with those with the lowest intake of processed foods. Those with the highest intake of whole foods were only about half as likely (0.64) to experience depression as those with the lowest intake of whole foods in their diets.

It was the opinion of the chief investigator, Dr. Tasnime N. Akbaraly, that the benefits of “whole foods” are not due to the influence of certain individual nutrients but “The protective effect of diet on depression comes from a cumulative and synergistic effect of different nutrients from different sources of foods, rather than the effect of one isolated nutrient.”

With a careful analysis, institution of various controls, and follow-up questions it was determined that it was not depression that predicted dietary behavior but rather that diet influenced depression.

Mrs. Ellen G. White, a reformer of the 19th century, spoke of depression associated with a meat diet. “I think that healthy, growing youth need a nourishing diet, especially when dispensing with meat, which has an immediate stimulating influence, to be followed by depression.” Letter 141, 1899