Eating a diet high in foods that spur inflammation in the body -- such as refined grains and soft drinks -- may raise the risk for depression in women, according to a new study.
The study, published in the journal Brain, Behavior, and Immunity, is based on data from 43,685 women ages 50 to 77 who did not have depression when they first entered the study in 1996, and who were followed until 2008. They completed food frequency questionnaires so researchers could get a feel of the sorts of diets they consumed, and also gave information on depression based on a strict and broad definition.
"We used a strict definition of depression that required both self-reported physician-diagnosed depression and use of antidepressants, and a broader definition that included women who reported either clinical diagnosis or antidepressant use," the team of researchers from Harvard University, the German Institute of Human Nutrition and Laval University wrote in the study.
At the end of the study period, 2,594 people had depression based on the stricter definition, and 6,446 people had depression based on the broader definition.
The researchers found that women who ate the most inflammation-linked foods had a 29 percent higher risk of depression when applying its broader definition, and a 41 percent higher risk of depression when applying its stricter definition, compared with women who ate the lowest amount of inflammation-linked foods.
The inflammation-linked diet consumed by the women in the study included lots of refined grains -- including bagels, pasta and white rice -- as well as soft drinks, red meat and margarine. This diet was also low in wine, coffee, olive oil and green leafy and yellow vegetables, study researcher Michel Lucas, Ph.D., a visiting scientist at the Harvard School of Public Health, told HuffPost. This diet was considered linked with inflammation because it was associated with levels of C-reactive protein, interleukin-6 and tumor necrosis factor α receptor 2 in the plasma; these are known markers of inflammation.
Lucas also noted that no one single food -- like pasta -- will, on its own, raise depression risk through inflammatory measures. Rather, it's necessary to look at the whole diet, "since all these food or nutrient are tied together," he said.
While it's possible that depression may spur people to eat more inflammation-linked foods, Lucas noted that the study purposefully excluded about 10,000 women who had depression at the start of the study to control for this effect.