Effects of Palmaria palmata on lipid metabolism and glycemic control in participants with hypercholesterolemia in a randomized double‐blind placebo‐controlled trial

Background Red algae have been reported to improve lipid and glucose metabolism in rats. We investigated the effects of Palmaria palmata (P. palmata), a red alga from northern Japan, on lipid metabolism and glycemic control in participants with hypercholesterolemia. Methods We conducted an 8‐week, randomized, double‐blind, placebo‐controlled, and parallel‐group comparison trial. The study enrolled Japanese participants with a serum low‐density protein cholesterol (LDL‐C) ≥120 mg/dL. The participants were randomly assigned to take either capsules containing P. palmata (2 g/day) or placebo capsules. The primary endpoint was the change in LDL‐C from baseline to week 8 and the secondary endpoints were the changes in other lipid parameters and glycemic control. Results Of the 104 participants completed the study protocol. There were no significant differences in change in LDL‐C, body mass index, waist circumference, or glycemic control between the two groups. However, serum triglyceride showed significantly greater improvement in women in the P. palmata group (−9.0 [−25.0, +5.0]) vs. those in the placebo group (−1.0 [−11.0, +19.0]; p = .03). Conclusions The present study did not show that P. palmata had significant effect on serum LDL‐C nor glycemic control, but hypertriglyceridemia could be ameliorated by administration of P. palmata in women.