The Effects of Orally Administered Beta-Glucan on Innate Immune Responses in Humans, a Randomized Open-Label Intervention Pilot-Study

RATIONALE To prevent or combat infection, increasing the effectiveness of the immune response is highly desirable, especially in case of compromised immune system function. However, immunostimulatory therapies are scarce, expensive, and often have unwanted side-effects. β-glucans have been shown to exert immunostimulatory effects in vitro and in vivo in experimental animal models. Oral β-glucan is inexpensive and well-tolerated, and therefore may represent a promising immunostimulatory compound for human use. METHODS We performed a randomized open-label intervention pilot-study in 15 healthy male volunteers. Subjects were randomized to either the β -glucan (n = 10) or the control group (n = 5). Subjects in the β-glucan group ingested β-glucan 1000 mg once daily for 7 days. Blood was sampled at various time-points to determine β-glucan serum levels, perform ex vivo stimulation of leukocytes, and analyze microbicidal activity. RESULTS β-glucan was barely detectable in serum of volunteers at all time-points. Furthermore, neither cytokine production nor microbicidal activity of leukocytes were affected by orally administered β-glucan. CONCLUSION The present study does not support the use of oral β-glucan to enhance innate immune responses in humans. TRIAL REGISTRATION ClinicalTrials.gov NCT01727895.