Stearidonic Acid and Lipid Metabolism

Overview

Evidence exists that EPA (eicosapentaenoic acid or C20:5n-3) supplementation can reduce the risk for coronary heart disease. EPA can be synthesized from α-linolenic acid (ALA or C18:3n-3), but conversion is low. It has been suggested that the rate-limiting step for this conversion is the Δ6-desaturation of ALA into stearidonic acid (SDA or C18:4n-3). Thus, providing oils rich in SDA may increase the endogenous synthesis of EPA. This may subsequently lower serum triacylglycerol concentrations, an effect frequently observed after EPA supplementation, especially in people with increased triacylglycerol levels. The objective is to study the effects of echium oil, rich in SDA on serum triacylglycerol concentrations in healthy overweight and slightly obese men and women. The minor objective is to study the effects of echium oil on the omega-3 index, which is negatively related to cardiovascular risk and defined as the proportion of EPA and DHA in red blood cells.

Using a randomized, double-blind, placebo controlled crossover design, subjects will receive in random order for six weeks with a washout period of at least 14 days, daily 10 g of echium oil or a high-oleic acid sunflower oil (HOSO) as control. Thirty-six healthy men and women, aged 18-70 yrs, with a body mass index between 25 and 35 kg/m2 will participate. Subjects with an increased BMI are at increased risk to develop hypertriglyceridemia. During the experimental period, subjects will receive daily one sachet at lunch and one sachet at dinner each providing 5 g of echium oil. During the control period, subjects will receive daily at the same time points sachets with the same amount of HOSO. The main study parameter is the change in fasting serum triacylglycerol concentrations. The secondary endpoint is the change in the omega-3 index.