Double-blind, parallel group, placebo-controlled study of Kjellmaniella crassifolia Miyabe (Gagome) in human: The potential of Gagome to activate the immune system

Background: Marine brown algae, Kjellmaniella crassifolia Miyabe (Gagome) is extensively harvested in Northern Japan and is known to help improve the immune system and prevent lifestyle diseases by its functional constituents, particularly the polysaccharide fucoidan. However, since most scientific findings come from animal studies, we examined its potential effectiveness in humans to raise immune functions, using small amounts of Gagome to avoid overconsumption of iodide. Methods: We set up a double-blind, placebo-controlled clinical trial (n=30 subjects for Gagome consumption; n=30 for placebo), in which 0.8 gram/day of Gagome containing 200 mg as dietary fiber (ca. 80 mg as fucoidan) was ingested for 8 weeks. The primary end-point was natural killer (NK) cell activity while other immune-related biomarkers, such as immunoglobulins (IgM and IgA) and cytokines (IL-12 and IFN-g) were secondary end-points.Results: No adverse effects were observed during the course of the clinical trial. We found that 8-week daily Gagome intake raised NK cell activities for the group with a relatively higher baseline number of NK cells (p=0.03). We also demonstrated that Gagome intake exerted a tendency to stimulate IgA secretion. These results indicate the possibility that Gagome intake may potentiate host defense systems in human as seen in animal studies.Conclusion: In this study, we used small amounts of Gagome (0.8 g daily) as an active test sample to avoid overconsumption of iodide, and found that this amount could enhance NK cell activities, particularly in the subclass with initially higher NK cell numbers. We also found an appreciable increment of IgA. With all of these facts, it seems that Gagome intake activates immune responses that contribute to the promotion of health through stimulation of the immune system.Keywords: clinical trial, dietary fiber, fucoidan, Gagome, natural killer cells