Does a Fatty, Sugary Diet Contribute to Holiday Blues?

While the holidays are a time of joy and fellowship for some, they often lead to bouts of depression for others. Do you suppose it has anything to do with indulging more frequently in foods that are high in fat and sugar? Just ask yourself, how do you feel after you have consumed your third piece of pie or gone back for seconds of an enormous holiday spread? You might not be overly pleased with yourself. But could unhealthy dietary habits predispose you to the “Holiday Blues” or even clinical depression over time? Recent research suggests that they might.

In an ongoing study of UK civil servants, researchers wanted to find out if diet might be associated with future depression¹. They found that women who ate a whole foods diet (more vegetables, fruits and fish) were about 60% less likely to experience recurrent depression symptoms over a 5-year period than those who ate a processed diet (sweetened desserts, fried foods, processed meat, refined grains, and high-fat dairy).

Another study of 1000 Australians arrived at the same conclusion. Women who ate a “western” diet (processed foods, fried foods, refined grains, sugary products, and beer) were more likely to develop depression and anxiety over a 5-year period than those who ate a “traditional” dietary pattern (vegetables, fruit, meat, fish, whole grains)².

How might this association between overall diet and development of depression over time be explained? Previous research has suggested a link between inflammation and depression. Healthy amounts of inflammation help our immune systems fight disease and recover from injuries. But excessive inflammation has been linked to conditions such as heart disease, strokes, diabetes and cancer.

Only recently has a possible link between an inflammatory dietary pattern and depression been specifically researched³. The researchers tracked the diet habits and health outcomes of over 43,000 women who were free of depression at the beginning of the study. Those who regularly drank sugary sodas, ate red meat or refined grains and infrequently consumed green leafy and yellow vegetables, wine, and olive oil over a 12-year period were 29-41% more likely to become depressed than those who ate a less inflammatory diet. Blood tests revealed that the women who ate more inflammatory foods also had significantly higher levels of the biomarkers for inflammation that have been previously associated with depression. So, chronic inflammation does appear to underlie the link between diet and depression.

These and many other studies show an association between dietary quality and depression. As encouraging as these findings seem, we really don’t know for certain if improving dietary quality might reduce the risk of depression⁴ or can help with recovery from depression. Many individual factors such as personal circumstances, genes, and other lifestyle behaviors also play a role.

But preliminary findings are promising enough that governments and the research community are taking action. A randomized, controlled trial is underway in Australia to determine if a dietary program can improve recovery from depression⁵. Each individual in the intervention group is participating in a series of individual counseling sessions with a dietitian to encourage and facilitate healthier eating while continuing to take medication. Blood tests of study participants might help strengthen the link between diet, indicators of inflammation, and symptoms of depression. The results of this study are eagerly awaited.

Europe has hopped on the band-wagon, too. The European Union has launched the 9 million euro MoodFOOD project to explore how improving food-related behavior and nutrition status might prevent depression⁶. Then they will develop nutrition guidelines and practical tools to guide policy. Extensive promotion throughout Europe is intended to lower the risk of depression and improve overall health of all European citizens.

Depression, appears to also be a disease of the body and not just the mind. Replacing processed, high-saturated fat and sugary foods with vegetables, fish, olive oil, and whole grains lowers our risk of chronic disease. There’s a good chance that such dietary measures may also benefit our emotional health, thus diminishing those Holiday Blues. So as we enter the season of joy and thankfulness, be mindful of your eating and make sure fitness remains a part of your daily routine.

References:

1. Dietary pattern and depressive symptoms in middle age. Akbaraly et al. Brit J Psych, 2009.
2. Association of western and traditional diets with depression and anxiety in women. Jacka
3. et al. Am J Psych, 2010.
4. Inflammatory dietary pattern and risk of depression among women, Lucas et al. Brain,
5. Behavior, and Immunity, 2014.
6. The association between diet quality, dietary patterns and depression in adults: a systematic
7. review. Quirk, Jacka et al. BMC Psychiatry, 2013.
8. A randomized trial of a dietary intervention for adults with major depression (the “SMILES” trial):
9. study protocol. Jacka et al, 2013.
10. MoodFOOD is a Multi-country collaborative project on the role of diet, food-related
11. behaviour, and obesity in the prevention of depression, 2014-2018.