High inflammatory diet found to increase likelihood of depression, new study finds

A new study published in the Journal of Affective Disorders has found a correlation between a highly inflammatory diet and an increased risk for depression.

And the researchers state their findings will have an impact on public health, as it’s an indication that a controlled diet could potentially help those with depression or prevent the illness in the first place.

The participants included 30,627 individuals from the U.S. who had been studied in the National Health and Nutrition Examination Survey (NHANES), a program of studies designed to assess the health and nutritional status of adults and children in the United States from 2007 to 2018.

The study aimed to assess the association between the dietary inflammatory index (DII), which is a scoring algorithm designed to estimate how diet impacts inflammation in the body and health outcomes as a result, to the cross-sectional study of NHANES.

The participants were asked questions regarding which foods they consume as their diet, and were given a score based on their dietary inflammation, and also rated for depression.

Based off this data, the researchers found what is called a J-shaped relationship, which is defined, according to academics, as a non-linear relationship between two variables and appears as a curve that initially falls, but then rises to become higher than the starting point, between DII and depression.

Meaning, at a set point, the amount of inflammation within the body appeared to exceed the body's capacity.

Then, as the J-shape indicates, the high inflammation in the body of the participants was found to begin to correlate with a significantly higher risk for depression for participants.

This J-shaped relationship showed a positive association between depression and inflammation, which remained intact even after the researchers adjusted for factors such as demographic data, lifestyle habits, disease, body mass index (BMI), and C-Reactive Protein (CRP), which is the level of a certain protein that your liver makes that results if bodily inflammation is too high.

This confirmed the association of high inflammation and depression in U.S. adults, according to study authors.

Research has linked a high intake of inflammatory foods, such as sugar and fat and a low intake of fruits and vegetables, to chronic diseases such as diabetes, cancer, and coronary heart disease, to name a few.

Meanwhile, other studies have shown that the Mediterranean diet, which is a low-inflammatory diet consisting of high amounts of vegetables and fruits, more seafood than meat and other high healthy-fat foods like olive oil, actually can aid in preventing, or improving chronic diseases.

And while past studies have found that many chronic diseases can actually get worse as a result of chronic inflammation in the body, which is known as a slow, long-term inflammation lasting for prolonged periods of several months to years, depression can also worsen from this chronic inflammation.

Approximately 280 million people are globally suffering with depression, according to the World Health Organization and this rate is increasing yearly.

In Canada alone, an estimated one in four Canadians struggle with depression serious enough to require treatment at some point over the course of their life.

According to Harvard Medical School, some high-inflammatory foods to avoid or limit include: refined carbohydrates, french fries or other fried foods, pop and other sugary drinks, red meat, processed meat, margarine, shortening, and lard.

Nutrient rich foods like leafy greens, nuts, tomatoes, olive oil, fatty fish and fruits should be consumed as part of an anti-inflammatory diet.

The researchers write that these findings have major implications for clinical practice as well as public health as diet is a factor that can be changed. Therefore, through choosing an anti-inflammatory diet or restricting pro-inflammatory foods, depression can be reduced and prevented, the researchers state.