Associations Between Intakes of Seafood and Long Chain <i>n</i>-3 Polyunsaturated Fatty Acids Supplement During Pregnancy and Subsequent Risk of Type 2 Diabetes Mellitus in a Large Prospective Cohort Study of Norwegian Women

Abstract

Background: While seafood is considered an important component of a healthy diet, concerns have been raised related to contaminant exposures and risk of type 2 diabetes mellitus (T2DM). The current study investigated the associations between total seafood, lean fish, fatty fish, and long chain n-3 polyunsaturated fatty acids (LCn-3PUFA) from supplements and risk of T2DM in women after pregnancy in a Norwegian population consuming more fish than in most Western countries. Methods: Women free of diabetes mellitus (DM) at baseline (n=60 831) who participated in the population-based Norwegian Mother, Father, and Child Cohort study (MoBa) were prospectively evaluated for incident T2DM identified through medication usage more than 90 days after delivery ascertained by the Norwegian Prescription Database. Dietary intake data was obtained by a validated 255-item semi-quantitative food frequency questionnaire (FFQ) which assessed habitual diet during the first four to five months of pregnancy. Contaminant intake (methylmercury (MeHg) and sum of dioxin and dioxin-like polychlorinated biphenyls (dl-PCBs)) was derived using a contaminant database and the FFQ. Findings: Median (IQR) age was 31 (27, 34) years at time of delivery and median follow up time was 7·5 (6·5, 8·5) years. T2DM occurred in 683 (1·1%) participants. Multivariable Cox regression analyses identified a reduced risk of T2DM with increasing energy adjusted lean fish intake per 25g/1000 kcal (HR 0·71, 95% CI 0·53 to 0·95, p=0·022). There were no associations between intake of total seafood, fatty fish, or LCn-3PUFA from supplements and T2DM in multivariable models. MeHg intake was low but the sum of dioxins and dl-PCBs (pg TEQ/kg bw/wk) exceeded the tolerable weekly intake (TWI) set by the European Food and Safety Authority (EFSA) for the majority of participants. Interpretation: Intake of lean fish was associated with reduced risk of pharmacologically-treated T2DM in Norwegian women. Funding Statement: The Norwegian Mother and Child Cohort Study (MoBa) is supported by the Norwegian Ministry of Health and Care Services and the Ministry of Education and Research. Declaration of Interests: None of the authors have any financial or personal relationship with other people or organizations. Ethics Approval Statement: The establishment of MoBa and initial data collection was based on a license from the Norwegian Data Protection Agency and approval from the Regional Committee for Medical Research Ethics and complies to the Norwegian Health Registry Act. The current research project was approved by all relevant agencies and the Regional Committee for Medical Research Ethics (Region West 2013/740) with amendments (14.03.2019) for including T2DM as an outcome measure.