Could 'Modern' Diet Raise Depression Risk?

A common diet among Australian women has been linked with a reduced risk of depression. It bolsters the argument that diet can influence depression susceptibility.

Can an apple a day keep depression away?

Well, maybe, a new study suggests—at least if it's combined with other fruits, vegetables, beef, lamb, fish, and whole-grain foods.

The study was headed by Felice Jacka, Ph.D., a research fellow at the University of Melbourne in Australia, and her colleagues. The results were published in the March American Journal of Psychiatry.

The study included more than 1,000 randomly selected Australian women aged 23 to 93. Subjects were evaluated for current major depression with the Structured Clinical Interview for DSM-IV-TR and for psychological symptoms with the General Health Questionnaire–12.

Subjects also completed a dietary questionnaire that had been validated for evaluating dietary intake in the Australian population. The questionnaire asked, for example, "Over the last 12 months, on average, how often did you eat pizza?" and a subject had to check off one of 10 answers, from "never" up to "three or more times a day." Similar questions were posed for 73 other foods and six alcoholic beverages.

The researchers then used a complex statistical procedure called "factor analysis" to analyze subjects' dietary habits. Simply put, all of the dietary variables recorded on the questionnaire were entered into a statistical package to see how they clumped together. This is a commonly used technique in nutrition research as it reveals how various foods tend to aggregate in people's diets.

Three common dietary patterns emerged from this analysis. One included vegetables, fruits, beef, lamb, fish, and whole-grain foods, or what the researchers called "a traditional [Australian] diet." A second included hamburgers, processed meats, pizza, chips, white bread, sugar, and flavored milk drinks, or what the researchers called "a Western diet." A third encompassed fruits, salads, fish, tofu, beans, nuts, and yogurt; the researchers named it "a modern diet."

Finally the researchers looked to see whether the pursuit of a traditional diet, Western diet, or modern diet could be linked with a current major depression in their subjects,. Possibly confounding variables such as age, socioeconomic factors, education, physical activity, smoking, and alcohol consumption were considered.

An inverse relationship was found between a traditional diet and the odds of having a current major depression. Subjects who ate such a diet had a one-third lower risk of having major depression than did subjects who did not eat such a diet. Even though the study was of a cross-sectional nature, this finding suggested that eating a traditional Australian diet might prevent depression.

In contrast, no relationship was found between a Western diet and the odds of having current major depression.