Probiotics for Enhanced Tissue Carotenoid Status: A Double-Blind, Randomized Controlled Trial

BACKGROUND: Skin carotenoid status (SCS) is a reliable indicator of carotenoid intake and has been shown to reflect interindividual variability in carotenoid metabolism and absorption. Although probiotics are known to enhance micronutrient status, their impact on phytochemicals like carotenoids remains unstudied. OBJECTIVES: This study aimed to determine whether the probiotic strain Bacillus subtilis Rosell-179 can potentiate the enhancing effect of carotenoid supplementation on carotenoid status and various health markers. METHODS: A 10-wk, double-blind, randomized controlled trial involving 37 premenopausal women (mean age of 40 y) was conducted. All participants took 2 supplements daily: a mixed carotenoid supplement (17 mg total carotenoids) and either a probiotic or a placebo. The primary outcome was SCS measured using a spectrophotometer. Secondary outcomes included plasma carotenoids and markers of antioxidant capacity, inflammation, and skin health (e.g., hydration and wrinkling). Dietary intake, physical activity, quality of life, and sleep were also monitored. Repeated measures were analyzed using linear mixed models with treatment and time (week 0, 5, and 10) as factors. RESULTS: SCS increased from baseline in both groups, with the probiotic group showing a larger estimated increase than placebo at week 10 by 1.1 units (P = 0.056; 95% confidence interval: 2.25, -0.05). Both groups increased plasma carotenoids from baseline to week 5 but did not continue to increase. There were no notable changes in plasma antioxidant capacity, immune status, or skin health measures. CONCLUSIONS: These findings indicate the potential of B. subtilis Rosell-179 to enhance SCS in healthy premenopausal women. This trial was registered at clinicaltrials.gov as NCT04511052 (https://clinicaltrials.gov/study/NCT04511052; registered on 12 August 2020).