Key Findings:
Whole milled flaxseed can significantly lower blood pressure – BP, effects which are due to omega 3 fats, lignan and protein. Inconsistent findings regarding the role that individual omega 3 fats play in BP lowering have been reported. The data assessed from the International Study of Macro- and Micro-nutrients and Blood Pressure (INTERMAP), a cross-sectional epidemiologic study of 4680 men and women ages 40 to 59 from Japan, People’s Republic of China, United Kingdom, United States found negative associations of total n-3 fats to systolic and diastolic pressure. ALA, EPA and DHA had similar effects on systolic and diastolic BP. n-3 PFA may favorably influence BP by improving endothelial vasodilator function, reducing reactivity of resistant vessel vascular smooth muscle, and increasing vascular compliance. Even though small reductions, decreased in systolic BP by “small” amounts (e.g., 2 mm Hg) can result in reduction of mortality rates of 6% for stroke and 4% for coronary heart disease.
Abstract:
Findings from short-term randomized trials indicate that dietary supplements of omega-3 polyunsaturated fatty acids (PFA) lower blood pressure of hypertensive persons, but effect size in nonhypertensive individuals is small and nonsignificant. Data are lacking on food omega-3 PFA and blood pressure in general populations. The International Study of Macro- and Micro-nutrients and Blood Pressure (INTERMAP) is an international cross-sectional epidemiologic study of 4680 men and women ages 40 to 59 from 17 population-based samples in China, Japan, United Kingdom, and United States. We report associations of food omega-3 PFA intake (total, linolenic acid, long-chain) of individuals with blood pressure. Systolic and diastolic blood pressure were measured 8 times at 4 visits. With several models to control for possible confounders (dietary, other), linear regression analyses showed inverse relationship of total omega-3 PFA from food (percent kilocalories, from four 24-hour dietary recalls) to systolic and diastolic blood pressures. With adjustment for 17 variables, estimated systolic blood pressure/diastolic blood pressure differences with 2 standard deviation higher (0.67% kcal) omega-3 PFA were 0.55/0.57 mm Hg (Z-score 1.33, 2.00); for 2238 persons without medical or dietary intervention, 1.01/0.98 mm Hg (Z 1.63, 2.25); for 2038 nonhypertensive persons from this sub-cohort, 0.91/0.92 mm Hg (Z 1.80, 2.38). For linolenic acid (largely from vegetable foods), blood pressure differences were similar, eg, for the 2238 “nonintervened” individuals, 0.97/0.87 mm Hg (Z 1.52, 1.95); blood pressure differences were 0.32/0.45 mm Hg for long-chain omega-3 PFA (largely from fish). In summary, food omega-3 PFA intake related inversely to blood pressure, including in nonhypertensive persons, with small estimated effect size. Food omega-3 PFA may contribute to prevention and control of adverse blood pressure levels. (Author’s abstract)