Effects of Ingesting Fucoidan Derived from Cladosiphon okamuranus Tokida on Human NK Cells: A Randomized, Double-Blind, Parallel-Group, Placebo-Controlled Pilot Study

The aim of this study was to evaluate the effects of ingesting fucoidan derived from Okinawa mozuku (Cladosiphon okamuranus) on natural killer (NK) cell activity and to assess its safety in healthy adults via a randomized, double-blind, parallel-group, placebo-controlled pilot study. Subjects were randomly divided into two groups-a placebo group (ingesting citric acid, sucralose, and caramel beverages; n = 20; 45.5 +/- 7.8 years (mean +/- standard deviation)) and a fucoidan group (3.0 g/day from beverages; n = 20; 47.0 +/- 7.6 years); after 12 weeks, blood, biochemical, and immunological tests were performed. Clinically adverse events were not observed in any of the tests during the study period. In addition, adverse events due to the test food were not observed. In the immunological tests, NK cell activity was significantly enhanced at 8 weeks in the fucoidan group, compared to before ingestion (0 weeks). In addition, a significantly enhanced NK cell activity was observed in male subjects at 8 weeks, compared with the placebo group. These results confirm that Okinawa mozuku-derived fucoidan enhances NK cell activity and suggest that it is a safe food material.