Association of Dietary Fish and Omega-3 Intake with Plasma Glucose
OBJECTIVE: Dietary fish and omega-3 fatty acids (n-3 FAs) are associated with a reduced risk of CHD mortality. However, enthusiasm for the intake of fish and n-3 FAs in type 2 diabetics has been tempered by reports of impaired glucose homeostasis. Most studies showing this negative impact of fish intake and n-3 FAs on glycemic control have been feeding or supplement studies conducted for short time periods. There are little data on the relationship of fish and n-3 FA intake to glucose levels in free-living diabetic populations. This study examines the associations of dietary fish and n-3 FAs with blood glucose levels among participants with type 2 diabetes from the Coronary Artery Risk Development in Young Adults (CARDIA) Study. METHODS: A total of 43 diabetic (i.e., fasting glucose levels >125 mg/dl) black and white men and women average age 33.6 years in 1992-1993 were included in analyses. Data on fish and n-3 FAs [α-linolenic acid (ALA, 18:3n-3), eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3)] were obtained from an interviewer administered diet history questionnaire. RESULTS: Average amount of fish consumed was 25.34 oz/mo. Mean intake of ALA, EPA, and DHA was 2.2 g/d, 0.07 g/d, and 0.13 g/d, respectively. Spearman rho correlations show a nonsignificant direct association of glucose with intake of fish (ρ=0.10), ALA (ρ=0.18), EPA (ρ=0.24), and DHA (ρ=0.11). For diabetics who consumed fish (n=29), mean glucose was 196.1 mg/dl compared to 208.9 mg/dl for the nonconsumers (n=14). Average glucose levels were highest for the highest tertile of n-3 FAs, e.g., for DHA intake (from lowest to highest) 191.1 mg/dl, 211.5 mg/dl, and 213.0 mg/dl. However, with adjustment for age, BMI, race, sex, education, alcohol and smoking this pattern changed, mean glucose levels were lowest for highest tertile of DHA intake, i.e, (from lowest to highest) 202.1 mg/dl, 215.9 mg/dl, and 196.3 mg/dl. CONCLUSION: In this cohort of free living young diabetics with typical low to moderate fish consumption, no significant differences in blood glucose levels were observed with intake of fish or n-3 FAs. Fish consumption at moderate levels does not appear to be associated with poor glycemic control.