Effect of brewers' yeast or beta-glucan derived from Saccharomyces cerevisiae on breast milk supply following preterm birth: The BLOOM randomised controlled trial

Objective: Breast milk is the optimal source of nutrition for preterm infants, however, low breast milk production is common following a preterm birth. This study aimed to determine if taking brewers yeast' or beta-glucan improves daily expressed breast milk volume. Design: Randomised, blinded, parallel, placebo-controlled trial. Setting: Three Australian tertiary level neonatal units. Patients: Mothers with a singleton or twin pregnancy who gave birth at less than 34 weeks' gestation. Interventions: Mothers were randomised within 72 hours of birth into three parallel groups in 1:1:1 ratio to receive either brewers' yeast, beta-glucan or placebo capsules for seven days. Main outcome measure: Total expressed breast milk volume over a 24-hour period on day seven of intervention. Results: A total of 105 mothers underwent randomisation between August 2022 and April 2024 (36 brewers' yeast, 35 beta-glucan, and 34 placebo). The adjusted mean difference in daily expressed breast milk volume was 94 mL/day (95% CI -51 to 239 mL/day) between the brewers' yeast and placebo groups, and -25 mL/day (95% CI -173 to 123 mL/day) between the beta-glucan and placebo groups. Maternal side effects were similar across groups. Conclusion: We found no clear effect of short-term administration of brewers' yeast or beta-glucan on breast-milk production following preterm birth; both interventions were well tolerated. Given the small sample size, these findings do not rule out the possibility of a clinically meaningful benefit of brewers' yeast and suggest further research with a larger sample size may be warranted to clarify the potential clinical impact. Trial registration number ACTRN12622000968774.