Researchers from Kwantlen Polytechnic University, the University of Toronto, the University of Victoria, and MacEwan University find that nutrition plays a major role in depression. The study also found that the likelihood of depression is higher among middle-aged and older women who are immigrants to Canada when compared to Canadian-born women.

Dr Karen Davison, Health Science program chair at Kwantlen Polytechnic University, led the study. She describes that lower intakes of fruits and vegetables were found to be linked to depression for both men and women immigrants and those born in Canada. Additionally, men were more likely to experience depression if they consumed higher levels of fat or lower levels of omega-3 eggs. For all participants, lower grip strength and high nutritional risk were associated with depression.

Various minerals and vitamins (e.g., magnesium, zinc, selenium) present in fruits and vegetables may reduce plasma concentrations of C-reactive protein, a marker of low-grade inflammation associated with depression. Researchers were interested to learn that omega-3 polyunsaturated fats were inversely associated with depression among men. They note that future research is needed to explore the pathways, but it is plausible that increased omega-3 fatty acid concentration in the diet may influence central nervous system cell membrane fluidity and phospholipid composition, which may alter the structure and function of the embedded proteins and affect serotonin and dopamine neurotransmission.

The study also found depression to be associated with having chronic pain and at least one chronic health condition for both men and women.

Researchers assert that it is important to consider influences earlier in life, including immigration status, education, and income, in addition to nutritional intake, as these are also crucial to older Canadians’ mental health.

According to the authors, immigrant status was associated with depression among women. Older immigrant women in the study may have reported depression as a result of the substantial stress associated with settling in a new country; immigrant men, who face many of these same settlement problems, did not have higher levels of depression than their Canadian-born peers. Although the authors did not have the data to explore why there was a gender difference, they posit that it may be that in these older married couples it was the husband who initiated the immigration process and the wives may not have had as much choice about leaving their homeland.

The study was based on analysis of the Canadian Longitudinal Study on Aging data and included a sample of 27 162 men and women aged 45 to 85 years, of whom 4739 are immigrants. The study was published in BMC Psychiatry. It is available at https://bmcpsychiatry.biomedcentral.com/articles/10.1186/s12888-019-2309-y [9].