The question of whether to use herbal supplements while breastfeeding is common, especially when seeking ways to support milk production. Milk thistle, or Silybum marianum, is a popular botanical remedy often discussed for lactation support. Many parents look for natural methods to enhance their milk supply, and this herb is frequently cited as a potential option. The core inquiry is whether it is both effective and safe for them and their nursing infant. This article explores milk thistle’s properties, traditional use, scientific evidence for its effectiveness, and its safety profile during lactation.
What is Milk Thistle and Its Traditional Use
Milk thistle is a flowering herb native to the Mediterranean region, identifiable by its thorny stem and distinctive purple flowers. The plant’s seeds contain active compounds collectively known as silymarin, which is extracted for use in supplements. Silymarin possesses antioxidant and anti-inflammatory properties, leading to the herb’s historical use in supporting liver and gallbladder function.
Beyond liver support, milk thistle has a long history in traditional medicine systems as a galactagogue—a substance believed to increase maternal milk flow. Its association with lactation is so ingrained that it is sometimes referred to as St. Mary’s Thistle. This traditional application suggests the plant has long been used to address perceived low milk supply, though scientific investigation into this effect is relatively modern.
Scientific Data on Increasing Milk Supply
The scientific community has explored milk thistle’s potential as a galactagogue, focusing primarily on its active component, silymarin. Some small clinical studies suggest a positive relationship between silymarin consumption and increased milk volume in new mothers. For example, one older study found that mothers who took 420 mg of micronized silymarin daily for over two months produced significantly more milk compared to a placebo group.
The proposed mechanism involves the herb’s potential to increase levels of prolactin, the hormone responsible for milk production. However, the overall evidence remains preliminary and is not conclusive enough to establish milk thistle as a guaranteed milk booster. Studies are often limited by small sample sizes, lack of rigorous control groups, or the use of purified silymarin rather than the whole herb. Therefore, while some data hints at a benefit, large-scale randomized controlled trials are still needed to confirm its efficacy.
Safety Profile When Breastfeeding
For breastfeeding parents, infant safety is the primary concern. Milk thistle is generally well-tolerated by adults, with the most commonly reported maternal side effects being mild gastrointestinal disturbances, such as diarrhea, nausea, or stomach upset.
A more serious, though rare, concern is the potential for allergic reaction, especially for individuals allergic to plants in the Asteraceae (daisy) family, which includes ragweed and artichokes. Data indicates that silymarin components are poorly absorbed orally and are not typically excreted into breast milk in measurable quantities. This minimal transfer suggests milk thistle is unlikely to adversely affect a breastfed infant. However, the lack of robust, long-term safety data specifically regarding breastfeeding infants means expert consensus remains cautious.
Practical Guidance and Quality Control
Before starting any herbal supplement, including milk thistle, consult with a healthcare professional, such as a lactation consultant, obstetrician, or pediatrician. These experts can help assess whether a perceived low milk supply is actually an issue and discuss appropriate strategies. This consultation is important to ensure the supplement will not interfere with existing maternal medications.
The quality of herbal products is a significant consideration, as dietary supplements are regulated differently than pharmaceuticals in the United States. The FDA does not approve supplements before marketing, leaving manufacturers responsible for safety and truthful labeling. Consumers should look for products that adhere to Good Manufacturing Practices (GMPs) and are standardized to contain a consistent amount of silymarin. The lack of stringent oversight can lead to variability in potency or contamination, underscoring the need to choose reputable brands.