Reduction of HbA1c levels by fucoxanthin-enriched akamoku oil possibly involves the thrifty allele of uncoupling protein 1 (UCP1): a randomised controlled trial in normal-weight and obese Japanese adults

Abstract

Lifestyle-related problems are becoming a major health threat in East Asian countries. Therefore, finding an efficacious nutraceutical for this population is important. One candidate is fucoxanthin (Fx), a carotenoid abundantly found in edible brown seaweed that has been associated with a number of valuable health-promoting benefits. Unfortunately, clinical studies of Fx are limited. In the present study, we aimed to evaluate the effects of Fx on obesity-related parameters in Japanese subjects harbouring an SNP associated with lifestyle-related problems. In all, sixty normal-weight and obese Japanese adults with BMI over 22 kg/m2 were single-blinded and randomly assigned to three Fx-dose cohorts and administered Fx-enriched akamoku oil containing Fx at 0, 1 or 2 mg/d for 8 weeks (n 20 per group). Parameters relating to obesity and serum Fx metabolites were measured before and after intervention, but no significant differences were observed between and within the groups. Despite no changes in visceral fat areas and resting energy expenditures after intervention, we observed a significant decline in HbA1c levels in the 2 mg/d Fx group compared with that in the 0 mg/d group (P < 0·05), which was correlated with an increase in serum fucoxanthinol (Fx metabolite) levels. In addition, HbA1c levels declined more significantly in subjects with G/G alleles of the uncoupling protein 1 (UCP1) gene than in those with the A/A and A/G alleles (P < 0·05). We conclude that although Fx supplementation does not affect visceral fat areas, it may reduce HbA1c levels in those harbouring the thrifty allele of UCP1-3826A/G.

Effects of daily intake of Harudori-kombu: A randomized, double-blind, placebo-controlled, parallel-group study

“…In this clinical trial, we observed no effect of Harudori-kombu on blood glucose profiles. A previous clinical trial has demonstrated a significant decline in HbA1c levels in the 2 mg/day fucoxanthin group compared with that in the placebo group [6]. Moreover, adiponectin levels were associated with blood glucose profiles, such as insulin resistance and glucose uptake.…”

Anti-Oxidant and Fucoxanthin Contents of Brown Alga Ishimozuku (Sphaerotrichia divaricata) from the West Coast of Aomori, Japan

“…Mikami et al reported clinical trial results on anti-diabetic effect by fucoxanthin administration [33]. Fucoxanthin was administered 1 mg or 2 mg/day for 8 weeks.…”

Therapeutic Effect of Seaweed Derived Xanthophyl Carotenoid on Obesity Management; Overview of the Last Decade

“…Unlike carotenes, which are known to be converted into Vitamin A, the accumulation and bioavailability of FXN and ASX vary among animal and human models [37,77]. The accumulation of dietary FXN and ASX (either intact or as metabolites) in the tissues have been reported in animal models [78][79][80][81], but few recent studies are available on bioavailability in humans [82,83]. Hence, it is inexpedient to draw a relative conclusion on the quantity of xanthophylls available for absorption in animal and human models.…”