Background: Only a limited number of studies have examined the vascular and postprandial effects of α-linolenic acid (ALA, C18:3n-3). Therefore, we performed a well-controlled trial focussing specifically on the effects of ALA on vascular function and metabolic risk markers during the fasting and postprandial phase in untreated (pre)hypertensive subjects.

Methods: In a double-blind randomized, placebo-controlled parallel study, 59 overweight and obese subjects (40 men and 19 women, aged 60 ± 8 years) consumed daily either 10 g of refined cold-pressed flaxseed oil, providing 4.7 g ALA (n = 29), or 10 g of high-oleic sunflower oil as control (n = 30) for 12 weeks.

Results: As compared with the control oil, intake of flaxseed oil did not change brachial artery flow-mediated vasodilation, carotid-to-femoral pulse wave velocity, retinal microvascular calibers and plasma markers for microvascular endothelial function during the fasting and postprandial phase. Fasting plasma concentrations of free fatty acid (FFA) and TNF-α decreased by 58 μmol/L (P = 0.02) and 0.14 pg/mL (P = 0.03), respectively. No differences were found in other fasting markers for lipid and glucose metabolism, and low-grade systemic inflammation. In addition, dietary ALA did not affect postprandial changes in glucose, insulin, triacylglycerol, FFA and plasma inflammatory markers after meal intake.

Conclusion: A high intake of ALA, about 3-5 times the recommended daily intake, for 12 weeks did decrease fasting FFA and TNF-α plasma concentrations. However, no effects were found on other metabolic risk markers and vascular function during the fasting and postprandial phase in untreated high-normal and stage I hypertensive subjects.

04 - EFFECT OF Α-LINOLENIC ACID ON VASCULAR FUNCTION AND METABOLIC RISK MARKERS DURING THE FASTING AND POSTPRANDIAL PHASE: A RANDOMIZED PLACEBO-CONTROLLED TRIAL IN UNTREATED (PRE)HYPERTENSIVE SUBJECTS