ARTERIAL COMPLIANCE IN OBESE SUBJECTS IS IMPROVED WITH DIETARY PLANT N-3 FATTY-ACID FROM FLAXSEED OIL DESPITE INCREASED LDL OXIDIZABILITY

The compliance or elasticity of the arterial system, an important inde x of circulatory function, diminishes with increasing cardiovascular r isk. Conversely, systemic arterial compliance improves through eating of fish and fish oil. We therefore tested the value of high intake of alpha-linolenic acid, the plant precursor of fish fatty acids. Fifteen obese people with markers for insulin resistance ate in turn four die ts of 4 weeks each: saturated/high fat (SHF), alpha-linolenic acid/low fat (ALF), oleic/low fat (OLF), and SHF. Daily intake of alpha-linole nic acid was 20 g from margarine products based on flax oil. Systemic arterial compliance was calculated from aortic flow velocity and aorti c root driving pressure. Plasma lipids, glucose tolerance, and in vitr o LDL oxidizability were also measured. Systemic arterial compliance d uring the first and last SHF periods was 0.42 +/- 0.12 (mean +/- SD) a nd 0.56 +/- 0.21 units based on milliliters per millimeter of mercury. It rose significantly to 0.78 +/- 0.28 (P<.0001) with ALF; systemic a rterial compliance with OLF was 0.62 +/- 0.19, lower than with ALF (P< .05). Mean arterial pressures and results of oral glucose tolerance te sts were similar during ALF, OLF, and second SHF; total cholesterol le vels were also not significantly different. However, insulin sensitivi ty and HDL cholesterol diminished and LDL oxidizability increased with ALF. The marked rise in arterial compliance at least with alpha-linol enic acid reflected rapid functional improvement in the systemic arter ial circulation despite a rise in LDL oxidizability. Dietary n-3 fatty acids in flax oil thus confer a novel approach to improving arterial function.