Serum long-chain omega-3 polyunsaturated fatty acids and risk of orthostatic hypotension

Long-chain omega-3 polyunsaturated fatty acids (PUFAs) from fish have been shown to lower blood pressure. However, there is little information about the association with orthostatic hypotension, for which hypertension is a risk factor. We investigated the associations between serum long-chain omega-3 PUFAs and orthostatic hypotension in 1666 middle-aged or older men and women free of cardiovascular disease (CVD), diabetes or hypertension in 1998-2001 in the Kuopio Ischemic Heart Disease Risk Factor Study (KIHD) in eastern Finland. We also investigated the associations with mercury exposure, a major source of which is fish, and which has been associated with higher CVD risk in KIHD. Orthostatic hypotension was defined as decrease in systolic blood pressure of at least 20 mm Hg or diastolic blood pressure of at least 10 mm Hg within 1 min of standing. Orthostatic hypotension was found in 146 participants (8.8%). The mean serum concentrations were 1.67% (s.d. 0.92) for eicosapentaenoic acid, 0.79% (s.d. 0.16) for docosapentaenoic acid (DPA) and 2.78 (s.d. 0.92) for docosahexaenoic acid of all serum fatty acids. The mean pubic hair mercury concentration was 1.5 μg g(-1) (s.d. 1.6). We did not find statistically significant associations between the serum long-chain omega-3 PUFAs or pubic hair mercury and risk of orthostatic hypotension, except for DPA. Those in the highest vs. the lowest serum DPA tertile had multivariate-adjusted 41% lower odds for orthostatic hypotension (95% confidence interval 7-63%, P-trend=0.02). Serum long-chain omega-3 PUFAs or mercury exposure were not associated with the risk of orthostatic hypotension, except for the inverse association with DPA.