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 <34 weeks' gestation. INTERVENTIONS: Mothers were randomised within 72 hours of birth into three parallel groups in a 1:1:1 ratio to receive either brewers' yeast, beta-glucan or placebo capsules for 7 days. MAIN OUTCOME MEASURE: Total expressed breast milk volume over a 24-hour period on day 7 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 mL/day to 239 mL/day) between the brewers' yeast and placebo groups and -25 mL/day (95% CI -173 mL/day 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.