Objective: The purpose of this study was to determine if Porphyra tenera extract (PTE) has immune-enhancing effects and is safe in healthy adults. Methods: Subjects (3x10³ ≤ peripheral blood leukocyte levels < 8x10³ cells/μl) who met the inclusion criteria were recruited for this study. Enrolled subjects (n=120) were randomly assigned to either the PTE group (n=60) who were given 2.5 g/day of PTE (as Porphyra tenera extract) in capsule form or the placebo group (n=60) who were given crystal cellulose capsules with the identical appearance, weight, and flavor as the PTE capsules for 8 weeks. Outcomes were assessed by measuring natural killer cell (NK-cell) activity, cytokines, and upper respiratory infection (URI), and safety parameters were assessed at baseline and 8 weeks. Results: Compared to baseline, NK cell activity (%) increased for all effector cell to target cell ratios in the PTE group after 8 weeks, but there were no changes in the placebo group (p<0.1). Subgroup analysis of 101 subjects without an URI revealed that NK-cell activity in the PTE group tended to be increased for all E:T ratios (E:T=12.5:1 p=0.068; E:T=25:1 p=0.036; E:T=50:1 p=0.081) compared to the placebo group. There was a significant difference between these two groups for the E:T=25:1 ratio, which increased from 20.3±12.0% at baseline to 23.2±12.4% after 8 weeks in the PTE group (p=0.036). There was no significant difference in levels of cytokines between these two groups. Conclusions: PTE supplementation appears to enhance immune function by improving NK-cell activity without adverse effects in healthy adults.

Codium fragile, a green algae, exhibit biological properties. In this study, we examined the effect of Codium fragile extract (CFE) on dextran sulfate sodium (DSS)-induced colitis. As the administration of CFE increased, the proliferation of Akkermansia muciniphila, which is key player in metabolic and gastrointestinal disorders, increased. After CFE administration for 10 weeks, acetic acid was revealed as the major metabolite in mouse cecum and β-glucuronidase activity in mouse feces is decreased. Further, CFE significantly alleviates the acute intestinal injury induced by DSS administration, including DAI scores and colon length. MPO activity in the colon was significantly reduced in the CFE-fed group, which indicated that CFE could inhibit neutrophils infiltration and inflammation in mice. In conclusion, a protective effect of CFE against DSS colitis suggests its clinical use for IBD patients.