Is There a Relationship between Vegetarianism and Seasonal Affective Disorder? A Pilot Study

Abstract

Background and Aim: Seasonal patterns of food intake are found in healthy individuals and particularly in patients with seasonal affective disorder (SAD). One nutritional choice is a vegetarian diet. Methods: In a Finnish population study, FINRISK 2012, information about diet and SAD was collected. In a Dutch outpatient clinic, SAD patients were asked if they were vegetarian. Results: The percentage of SAD patients among Finnish vegetarians was 4 times higher than in the normal population. The percentage of vegetarians among the SAD patients in a Dutch outpatient clinic was 3 times higher than in the normal population. In the Dutch population, the seasonal loss of energy, in particular, is related to vegetarianism. Conclusion: These findings suggest a possible link between vegetarianism and SAD.

The Role of Diet, Eating Behavior, and Nutrition Intervention in Seasonal Affective Disorder: A Systematic Review

“…Among them, studies were excluded for not focusing on SAD ( n = 12), including subjects with other major depression as comparisons ( n = 1), outcomes unrelated to our objective ( n = 3), being review articles ( n = 2), the full text not being available ( n = 1), supplementation being given not through oral administration ( n = 2), not involving dietary intervention ( n = 5), and not using a validated tool for SAD screening ( n = 2). In total, we included data from 11 studies in the current systematic review (Krauchi and Wirz-Justice, 1988 ; Rosenthal et al, 1989 ; Berman et al, 1993 ; Oren et al, 1994 ; Krauchi et al, 1997 ; Danilenko et al, 2008 ; Mischoulon et al, 2010 ; Donofry et al, 2014 ; Frandsen et al, 2014 ; Meesters et al, 2016 ; Morales-Munoz et al, 2017 ).…”

“…One cross-sectional study investigated the possible link between vegetarianism and SAD (Meesters et al, 2016 ). By using available data from the Finnish national FINRISK 2012 study and data from the outpatient clinic for SAD in the Netherlands, the author of that study found an association between being vegetarian and SAD.…”

“…Two studies did not employ valid prognostic factor measurement (Krauchi and Wirz-Justice, 1988 ; Donofry et al, 2014 ). Four studies only presented categorical prognostic factor data or did not articulate the cut-off points of their continuous variables (Krauchi and Wirz-Justice, 1988 ; Krauchi et al, 1997 ; Donofry et al, 2014 ; Meesters et al, 2016 ). Only one study stated that the method of prognostic factor measurement was not the same for all study participants, and the proportion of the study sample that completed data for prognostic factors was inadequate (Krauchi et al, 1997 ).…”

“…In the outcome measurement domain, only one study had a low risk of bias, while the other five studies presented a medium risk of bias, which resulted from an unclear definition of outcome (Krauchi and Wirz-Justice, 1988 ; Morales-Munoz et al, 2017 ), inadequately valid outcome measurement methods (Krauchi and Wirz-Justice, 1988 ; Kurlansik and Ibay, 2012 ; Donofry et al, 2014 ), and inconsistent outcome measurements for each study participant (Berman et al, 1993 ). Since most studies used analysis of variance and did not perform correlation analysis (Krauchi and Wirz-Justice, 1988 ; Berman et al, 1993 ; Krauchi et al, 1997 ; Meesters et al, 2016 ), they did not adjust for potential confounders. For the two studies that used logistic regression to explore the relationship between prognostic factors and SAD severity, Donofry et al adjusted for age and gender (Donofry et al, 2014 ), while Meesters et al adjusted for age and gender in the Dutch data, and only gender in the Finnish data (Meesters et al, 2016 ).…”

“…Seasonal affective disorder (SAD) is an almost-recurring annual depression with seasonality due to the alteration of mood, hormones, and gene expressions (Wirz-Justice, 2018 ). The onset of depression typically appears in autumn or winter with subsequent remission in spring or summer (Meesters et al, 2016 ). In the revised version of the Diagnostic and Statistical Manual of Mental Disorders III (DSM-III-R), the characteristics of SAD were first described by Rosenthal et al as hypersomnia, overeating, and symptoms that respond to changes in climate and latitude (Rosenthal et al, 1984 ).…”