Positive Health Online

Abstract

LAI and COLLEAGUES, 1. School of Medicine and Public Health, University of Newcastle, Callaghan, NSW 2308, Australia. jun.lai@uon.edu.au; 2. Hunter Medical Research Institute, New Lambton Heights, NSW 2305, Australia. christopher.oldmeadow@hmri.com.au; 3. School of Medicine and Public Health, University of Newcastle, Callaghan, NSW 2308, Australia; Hunter Medical Research Institute, New Lambton Heights, NSW 2305, Australia. alexis.hure@newcastle.edu.au; 4. School of Medicine and Public Health, University of Newcastle, Callaghan, NSW 2308, Australia; Hunter Medical Research Institute, New Lambton Heights, NSW 2305, Australia. mark.mcevoy@newcastle.edu.au; 5. Department of Psychiatry, VU University Medical Center, Amsterdam 1070BB, The Netherlands. s.hiles@vumc.nl; 6. Division of Medicine, John Hunter Hospital, New Lambton Heights, NSW 2305, Australia. michael.boyle@hnehealth.nsw.gov.au; 7. School of Medicine and Public Health, University of Newcastle, Callaghan, NSW 2308, Australia; Hunter Medical Research Institute, New Lambton Heights, NSW 2305, Australia; Division of Medicine, John Hunter Hospital, New Lambton Heights, NSW 2305, Australia. john.attia@newcastle.edu.au investigate the hypothesis that inflammatory markers interleukin (IL)-6 and C-reactive protein (CRP) mediate associations between antioxidant and fatty acid intakes and depression.

Background

Antioxidants and fatty acids are associated with depression and inflammation, and inflammation appears to predict depression risk; hence, the associations between these nutrients and depression may be mediated by inflammation.

Methodology

The authors hypothesized that inflammatory markers interleukin (IL)-6 and C-reactive protein (CRP) mediate the associations between antioxidant and fatty acid intakes, and depression. Participants were from the Hunter Community Study, a longitudinal cohort of adults aged 55-85 years. Dietary intake was assessed using the Older Australian's Food Frequency Questionnaire. Fasting blood samples were drawn for analysis of nutrient and inflammatory biomarkers. Depressive symptoms were assessed using the 20-item Center for Epidemiologic Studies-Depression scale at baseline and at 5-year follow-up. Linear mixed models were used to investigate longitudinal associations between dietary intakes and depression, and mediation analyses were carried out to determine if IL-6 and/or CRP were the mediators. Analyses were conducted on men and women separately and adjusted for potential confounders.

Results

Fruit and monounsaturated fat intakes were negatively associated with depression, whereas total fat and saturated fat intakes were positively associated with depression in both sexes. Omega-3 polyunsaturated fat was inversely associated with depression in men only. IL-6 was a significant mediator of the association between fruits with low carotenoid content and depression in women. CRP significantly mediated the relationship between total fat, saturated fat, and monounsaturated fat intakes and depression in women, and saturated fat intake and depression in men.

Conclusion

Our findings raise the possibility that the association between fatty acid intake and depression is partially mediated by inflammatory markers.

References

Lai JS1, Oldmeadow C2, Hure AJ3, McEvoy M4, Hiles SA5, Boyle M6, Attia J7. Inflammation mediates the association between fatty acid intake and depression in older men and women. Nutr Res. 36(3):234-45. Mar 2016. doi: 10.1016/j.nutres.2015.11.017. Epub Nov 26 2015.