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Intakes of Fish and Long-chain n-3 Polyunsaturated Fatty Acid Supplements During Pregnancy and Subsequent Risk of Type 2 Diabetes in a Large Prospective Cohort Study of Norwegian Women

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posted on 18.08.2021, 00:33 by Jannike Øyen, Anne Lise Brantsæter, Ole Jakob Nøstbakken, Kåre I. Birkeland, Margareta Haugen, Lise Madsen, Grace M. Egeland
OBJECTIVE
To investigate associations between intakes of total fish, lean fish, fatty fish, and long chain n-3 polyunsaturated fatty acid (LCn-3PUFA) supplements and risk of type 2 diabetes in women after pregnancy. Furthermore, to compare the estimated intakes of methylmercury (MeHg) and sum of dioxins and dioxin-like polychlorinated biphenyls (dl-PCBs) to tolerable weekly intakes (TWI).
RESEARCH DESIGN AND METHODS
Women free of diabetes at baseline (n=60,831) who participated in the population-based Norwegian Mother, Father, and Child Cohort study (MoBa) were prospectively evaluated for incident type 2 diabetes 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 food frequency questionnaire (FFQ) which assessed habitual diet during the first four to five months of pregnancy. MeHg and sum of dioxins and dl-PCBs intakes were derived using a contaminant database and the FFQ.
RESULTS
Median (IQR) age was 31 (27, 34) years at time of delivery and follow-up time was 7.5 (6.5, 8.5) years. Type 2 diabetes occurred in 683 (1.1%) participants. Multivariable Cox regression analyses identified lower risk of type 2 diabetes with increasing energy-adjusted lean fish intake per 25 g/1000 kcal (HR 0.71, 95% CI 0.53-0.95, p=0.022). However, in stratified analyses, a lower risk was found only in women with pre-pregnancy BMI ≥25 kg/m2. There were no associations between intake of total fish, fatty fish, or LCn-3PUFA supplements and type 2 diabetes. MeHg intake was low, but the sum of dioxins and dl-PCBs (pg TEQ/kg bw/wk) exceeded the TWI set by the European Food and Safety Authority (EFSA) for the majority of participants.
CONCLUSIONS
Intake of lean fish, but not fatty fish or LCn-3PUFA supplements, was associated with lower risk of pharmacologically treated type 2 diabetes in Norwegian women who were overweight or obese. Fatty fish, which contain dioxins and dl-PCBs, did not increase the risk of type 2 diabetes, but the exceedance of the EFSA TWI for dioxins and dl-PCBs is a health concern.

Funding

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. The Norwegian Ministry of Health and Care Services and the Ministry of Education and Research had no role in the design of the study, data collection and analyses, interpretation of data, decision to publish, or preparation of the manuscript.

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