Dietary glycemic index and load and the risk of postpartum depression in Japan: The Osaka Maternal and Child Health Study

Background: Given suggestions that postpartum depression may be due to the sudden fall in insulin levels occurring after delivery via a decrease in serotonergic function, this condition might be alleviated by a high-glycemic index (GI) diet, which would stimulate the secretion of insulin and thereby facilitate the transport of tryptophan, the precursor of serotonin, in the brain. We examined the association between dietary GI and glycemic load (GL) and postpartum depression. Methods: Subjects were 865 Japanese women. Dietary GI and GL were assessed during pregnancy using a validated, self-administered, comprehensive diet history questionnaire. Postpartum depression was defined as present when the subject had an Edinburgh Postnatal Depression Scale score of >= 9 at 2-9 months postpartum. Results: A total of 121 women (14.0%) were classified as having postpartum depression. After adjustment for potential confounding factors, no evident dose-response association between dietary GI and postpartum depression was observed (P for trend = 0.18). However, compared with dietary GI in the first quartile, dietary GI in the third quartile, but not the fourth quartile, was significantly associated with a decreased risk of postpartum depression (multivariate odds ratio: 0.56, 95% confidence interval: 0.32-0.995). There was no evident independent association for dietary GL (P for trend = 0.13). Limitations: Dietary data collected during pregnancy rather than postpartum were used. Conclusions: This preliminary study failed to substantiate a clear inverse relationship between dietary GI and GL and postpartum depression. Considering the plausibility of the proposed mechanism, however, further investigation using postpartum dietary data is warranted. (C) 2007 Elsevier B.V. All rights reserved.