Trade-offs in rigor and generalizability in a diet trial of glycemic control in adults with type 2 diabetes using whole foods and dietary supplements

Association of Oily and Nonoily Fish Consumption and Fish Oil Supplements With Incident Type 2 Diabetes: A Large Population-Based Prospective Study

OBJECTIVE

To evaluate associations of oily and nonoily fish consumption and fish oil supplements with incident type 2 diabetes (T2D).

RESEARCH DESIGN AND METHODS

We included 392,287 middle-aged and older participants (55.0% women) in the UK Biobank who were free of diabetes, major cardiovascular disease, and cancer and had information on habitual intake of major food groups and use of fish oil supplements at baseline (2006-2010). Of these, 163,706 participated in one to five rounds of 24-h dietary recalls during 2009-2012.

RESULTS

During a median 10.1 years of follow-up, 7,262 incident cases of T2D were identified. Compared with participants who reported never consumption of oily fish, the multivariable-adjusted hazard ratios of T2D were 0.84 (95% CI 0.78-0.91), 0.78 (0.72-0.85), and 0.78 (0.71-0.86) for those who reported <1 serving/week, weekly, and ≥2 servings/week of oily fish consumption, respectively (P-trend < 0.001). Consumption of nonoily fish was not associated with risk of T2D (P-trend = 0.45). Participants who reported regular fish oil use at baseline had a 9% (95% CI 4-14%) lower risk of T2D compared with nonusers. Baseline regular users of fish oil who also reported fish oil use during at least one of the 24-h dietary recalls had an 18% (8-27%) lower risk of T2D compared with constant nonusers.

CONCLUSIONS

Our findings suggest that consumption of oily fish but not nonoily fish was associated with a lower risk of T2D. Use of fish oil supplements, especially constant use over time, was also associated with a lower risk of T2D.