Objectives: To examine in two tests the potential of kaki (persimmon) extract-containing diet (KE diet) to reduce malodorous volatile sulfur compounds (VSC), such as hydrogen sulfide (H₂S), methyl mercaptan (CH₃SH) and dimethyl sulfide (CH₃SCH₃), as well as on subjective fecal odor on healthy adults.
Methods: In the first test, 11 subjects were given garlic-containing soup. For a period of time, they were given a single dose of KE diet (150 mg as kaki extract) with water, and only water for the rest of the study period. Two hours after the administration, oral gas samples were collected from individual subjects and analyzed for VSC. In the second test, 14 subjects were given a single dose of KE diet for 7 days. Fecal samples were collected from individual subjects before and after the 7-day KE diet intervention. Levels of VSC were determined and the magnitude of subjective fecal odor was estimated based on ratings in the self-administered questionnaire.
Results: Levels of CH₃SCH₃ in oral gas were significantly lowered when subjects were on a KE diet. On the other hand, although decreases in the level of any VSC in feces before and after the 7-day KE diet intake did not reach a statistical significance, subjective fecal odor significantly improved by the KE diet intake.
Conclusion: KE diet appears to have a beneficial effect on VSC-associated oral malodor and subjective fecal odor.

Secretory immunoglobulin A (s-IgA) in saliva constitutes the first-line barrier to the entry of pathogens into the body, implying its critical role in mucosal immunity.To examine the effect of a shark liver oil (SLO)-containing diet on salivary s-IgA concentration in healthy male and female adults, 42 subjects were assigned to either placebo or 6 weeks of a 2,400 mg SLO-containing diet (1,500 mg as SLO) and assessed in a randomized, double-blind, placebo-controlled, parallel group trial.Salivary s-IgA concentration significantly increased at week 6 in the SLO group (P = 0.033), but not in the placebo group.Moreover, there was a significant difference between groups in the magnitude of change from baseline to week 6.No intervention-related adverse event or abnormal changes of laboratory test parameters were observed throughout the study period.In conclusion, an SLO-containing diet increases salivary s-IgA in healthy adults.