Is Brewer’s Yeast safe while breastfeeding?

Summary of use during breastfeeding

The dead yeast cells of brewer’s yeast (Saccharomyces cerevisiae) is used as a dietary supplement to enhance milk production. No scientifically valid studies in humans have been performed that establish any effect of brewer’s yeast on milk supply. Although studies in ruminants indicate that brewer’s yeast might increase milk supply, the effect is attributed to improved nutrition (increases in vitamin B and chromium) rather than any specific effect on lactation.[1] Some side effects, mostly gastrointestinal, have been reported by nursing mothers taking brewer’s yeast. There are wide variations in the content of brewer’s yeast products.[1] In a US survey, of 190 mothers who used brewer’s yeast as a galactogogue 46% thought it increased milk supply.[2]

Dietary supplements do not require extensive pre-marketing approval from the U.S. Food and Drug Administration. Manufacturers are responsible to ensure the safety, but do not need to prove the safety and effectiveness of dietary supplements before they are marketed. Dietary supplements may contain multiple ingredients, and differences are often found between labeled and actual ingredients or their amounts. A manufacturer may contract with an independent organization to verify the quality of a product or its ingredients, but that does not certify the safety or effectiveness of a product. Because of the above issues, clinical testing results on one product may not be applicable to other products. More detailed information about dietary supplements is available elsewhere on the LactMed Web site.

Effects on the breastfed infant

In a survey of 108 nursing mothers in South Africa, one woman reported cramps in her infant after she used brewer’s yeast as a galactogogue.[3]

Effects on milk supply

In a survey of nursing mothers in Australia, 592 mothers were taking brewer’s yeast as a galactogogue. On average, mothers rated brewer’s yeast as slightly less than “moderately effective” on a Likert scale. Sixty-five mothers (11%) taking brewer’s yeast reported experiencing an adverse reaction, most commonly weight gain, stomach cramps, dry mouth and nausea. Twelve (2%) reported having more than one adverse effect.[4]

A multicenter, randomized, double-blind study compared brewers’ yeast and beta-glucan derived from Saccharomyces cerevisiae to placebo in the milk produced by mothers of infants in the NICU at 7 or 21 days postpartum. No meaningful differences in milk output was found between the two products and placebo.[5]

Levels in milk

Maternal Levels. Relevant published information was not found as of the revision date.

Infant Levels. Relevant published information was not found as of the revision date.