Oryza Ceramide® containing rice-derived glucosylceramides and a ceramide decreases cumulative days with cold symptoms in Japanese healthy subjects

抄録

Background and objective: Plant-derived glucosylceramides (GlcCer) have been clinically reported to enhance skin barrier functions. GlcCer and ceramides (Cer) interact with immune-stimulating receptors on antigen-presenting cells, such as c-type lectin receptors and toll-like receptor 4. However, the clinical and immunological efficacies of orally ingested GlcCer remain unknown. Therefore, we herein conducted a clinical trial on the effects of rice-derived GlcCer (Oryza Ceramide^®: OC) on cold symptoms, immune parameters, and SF-36 scores. Methods: OC (type PCD, 60 mg daily) containing 1.8 mg of GlcCer and 0.09 mg of Cer [t18:0/24:0] was used as the active sample. We enrolled 44 healthy Japanese individuals who are prone to catching colds and a low immune score. All subjects were randomly allocated to an active group (n = 22) or placebo group (n = 22). Capsules containing OC or the placebo were administered for 8 weeks. Cold symptom scores during the intervention were the primary outcome, while immune parameters and SF-36 scores measured after the 8-week intervention were the secondary outcomes. Results: Forty subjects completed the trial, and the per protocol set comprised 19 and 21 in the active and placebo groups, respectively. Regarding the primary outcome, cumulative days with cold symptoms, such as nasal congestion, throat irritation, a cough, headache, muscle pain, and diarrhea, was lower in the OC group. Among the secondary outcomes, physical functioning in SF-36 scores was improved in the OC group. Regarding immune parameters, a negative correlation was observed between changes in blood T-lymphocytes and cumulative days with cold symptoms. Laboratory tests revealed no abnormalities to suggest adverse effects of OC. Conclusions: OC consisting of GlcCer attenuated typical cold symptoms, such as nasal congestion, throat irritation, a cough, headache, muscle pain, and diarrhea, and improved physical conditions. Changes in T-lymphocytes may be one of the mechanisms by which OC ameliorates cold symptoms.