Effects of oral intake of heat-killed Lactobacillus brevis SBC8803 (SBL88™) on dry skin conditions: A randomized, double-blind, placebo-controlled study

Abstract

Lactobacilli are important in intestinal homeostasis, which involves the regulation of immune function, digestive health, cholesterol absorption and intestinal tumor growth amongst others. Our previous investigations have suggested that oral intake of heat-killed Lactobacillus brevis (L. brevis) SBC8803 (SBL88™) suppresses dermatitis by modulating the immune function in an atopic dermatitis mouse model. The aim of the present study was to investigate the effect of heat-killed L. brevis SBC8803 intake on skin hydration conditions in humans. A randomized, double-blind, placebo-controlled study was conducted with volunteers with slightly higher levels of transepidermal water loss (TEWL) on the forearm. The subjects (126 people aged between 21 and 59 years) were randomly allocated to three groups so that the level of TEWL and the age were distributed equally among the groups. The subjects took placebo or heat-killed L. brevis SBC8803 at a daily dose of 25 or 50 mg for 12 weeks. Following the exclusion of eight subjects for plausible reasons (two withdrawals from the study, two for study violations, one for not meeting exclusion criteria and three due to their physical condition), 118 subjects were subjected to the analysis. The results of the present study revealed that following the analysis of the whole populations, marginal differences were observed in TEWL (for example, suppression of skin water loss) at the neck in the 25 mg/day group at week 8 and at the lower eye region in the 50 mg/day group at week 4 (P=0.05 and 0.09, respectively, compared with the placebo group analyzed by Dunnett's test). A significant increase in corneal hydration was also observed at the neck in the 25 mg/day group at week 12 (P=0.06, as compared with the placebo group as analyzed by Dunnett's test). In the analysis of the subpopulations whose habitual frequency of taking lactic fermentation products was less than once per week, the levels of corneal hydration at the neck (in the 50 mg/day group) and lower eye region (in the 25 mg/day group) were significantly increased at week 12 (P<0.05). In conclusion, the results of the present investigation suggest that oral intake of heat-killed L. brevis SBC8803 is effective at improving skin hydration conditions in populations with low habitual frequency of taking lactic fermentation products.

Keywords: Lactobacillus; clinical study; skin care; skin moisturizing; transepidermal water loss.

Figure 1.

Procedure for the selection and the analysis of subjects. Group P, subjects who received a placebo; group L, subjects who received low-dose heat-killed L. brevis SBC8803; group H, subjects who received high-dose heat-killed L. brevis SBC8803. Values in parentheses denote the number of subjects. The reasons for subject exclusion were: Violation of the study restrictions (n=2 in group L); conformity to the exclusion criteria (n=1 in group H); and judgement by the principle investigator (Dr Sumio Kondo) based on the subjects' physical conditions (n=1 in group L and n=2 in group H). The subject allocation was performed by Yoshihisa Kibune (TTC Co., Ltd., Tokyo, Japan).