Lower Risk of Type 2 Diabetes in Chinese Women with Higher Intakes of Fish and DHA/EPA

June 20, 2011


Fish, Shellfish, and Long-Chain n-3 Fatty Acid Consumption and Risk of Incident Type 2 Diabetes in Middle-aged Chinese Men and Women
Villegas, R. et al., Amer. J. Clin. Nutr., in press , 2011


This prospective population-based study included 64,193 women and 51,963 men from Shanghai, China who were free at baseline of type 2 diabetes, cardiovascular disease, and cancer. Dietary assessments of their intakes of fish/shellfish and long-chain omega-3 fatty acids (as DHA plus EPA) were determined. Follow-ups and statistical information were collected for a total follow-up time of 8.9 years for the women (SWHS-Shanghai Women’s Health Study) and 4.1 years for the men (SMHS).

The median daily intakes for fish and shellfish were 31.6 gm and 7.7 gm , respectively, for the women. A significant inverse relation between the intake levels of fish and shellfish and the risk of type 2 diabetes was found for the women such that those in the top 20 % with respect to intakes (median of 99.1 gms/day ) had a 14-17 % lower risk of disease development as compared to those (lowest intakes) with median intakes of only 13.6 gms/day when adjusting for other confounding factors. In the men, the lower apparent risk for disease development at the higher intakes did not reach statistical significance. In the women (SWHS) , higher intakes of (DHA plus EPA) were correlated with lower risks for disease development with the highest consumers (median intakes of 200 mg /day) exhibiting a 16-18 % lower risk for disease as compared to those with median intakes of only 20 mg/day. The authors stated that the inverse relations they found in women for fish/shellfish intakes (including the omega-3 fatty acids ) were also not associated with any deleterious effects.

Dr. Holub's Comments:

Those women with the highest intakes (top 20 % of the population) of fish/shellfish in this population study had median intakes of 99.1 gms/day or the equivalent 7 fish servings/week (based on one serving weighing 100 gms or 3.5 ounces). Such intake levels of fish are very rare in North America , Europe, and numerous other countries. As example, North Americans average approx. one fish serving/week. However, it is noted that the highest median intakes of (DHA plus EPA) reported in the present study (SWHS) were 200 mg/day which is much less than expected if the 7 fish servings/week had been typical of the more popular fish as consumed in North America (eg., salmon, others). In this regard, it is noted that carp (including silver and grass carp) are popular in China as are tilapia and these contain much lower amounts of DHA plus EPA per serving than salmon . Current intakes per person of DHA plus EPA in North America from fish/seafood are approx. 130 mg/day.

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