Anise (Pimpinella anisum) seeds contain anethole, which is a phytoestrogen. Anise is a purported galactogogue,[1-6] and is included in some proprietary mixtures promoted to increase milk supply; however, few scientifically valid clinical trials support this use. Galactogogues should never replace evaluation and counseling on modifiable factors that affect milk production.[7,8] Maternal anise ingestion reportedly imparts an odor to breastmilk,[9] possibly because anethole is excreted into breastmilk.[10] Anise is "generally recognized as safe" (GRAS) as a flavoring by the U.S. Food and Drug Administration. Elevated liver enzymes occurred in a woman taking Mother's Milk Tea, which contains anise.[11] Excessive maternal use of an herbal tea containing anise and other herbs appeared to cause toxicity in two breastfed newborns, consistent with toxicity caused by anethole.
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.