• Dr. Gladis Walter

Milk Thistle in pregnancy and lactation: what does science says?

While searching material to write this article, I had a purpose in mind: to write for women that are breastfeeding.

Breastfeeding: variations of the same question that I receive.

• Is Milk thistle tea or extract safe during lactation?

• Does it increase the milk production?

• Is Milk thistle a galactagogue?

• If I drink the tea my baby will have more milk?

In previous generations, women would recommend herbal tea for others because they observed an improvement on the milk production. There is a popular demand for herbal galactagogues in many countries, in recent years, and Milk thistle (Silybum marianum) is among these popular herbs. Because we live in the 21st century, we want to know what works and why. Is there any scientific data that shows that Milk thistle increases milk production during breastfeeding?

To answer this question, we need to look back in time. Milk thistle is cited many times in the Bible and from the period 40-90 AD it was described by the Greek physician and botanist Dioscorides as an herb with healing properties against snakebites. In the middle ages, it was used mainly to treat liver problems. In the 1500, another pharmacological application was found: an herbal medicine to treat depression and emotional issues. By the time Spanish, English and Portuguese settled in the Americas, Milk thistle was associated with snakebites, liver, depression, but not milk production!

Although this plant is found in many parts of the world – North and South America, Australia, Southern Europe, Northern Africa and Asia-, most of the scientific research supports other therapeutic applications: cancer, diabetes, Alzheimer’s and Parkinson’s diseases. Interestingly, the focus of research remains on the Middle Ages discovery: the hepatoprotective effect of the plant, now attributed to Silymarin, the major constituent of milk thistle extract.

  1. What does science tell us about breastfeeding and Milk Thistle? The research points in direction to Silymarin as well. There are some reviews on herbal and pharmaceutical galactagogues but only one peer reviewed publication, from 2008, dedicated to women and breastfeeding. The work describes the treatment of a group of women during the period of lactation, when they were treated with micronized Sylimarin, a special formulation to improve its solubility and absorption. It was observed an increase on 85.94% of the daily milk production during the period of 63 days, when compared to the day zero. The placebo group had an 32.09% increase, for the same period. However, micronized Sylimarin is not approved in US. Milk thistle is available as a dietary supplement only.

  2. What are the answers? We still don't know exactly the effect of Milk thistle as galactagogue, since there is not enough data available. There is only one publication, in humans, where the improved compound sylimarin was tested. Because most of the women take the dry herb/seeds or the non-standardized extracts, and the active compounds of milk thistle have poor solubility and absorption, many questions still remain.

  3. If you know about new studies, or would like to send us your opinion, send as your message.


Bazzano, A. N., Hofer, R., Thibeau, S., Gillispie, V., Jacobs, M., & Theall, K. P. (2016). A Review of Herbal and Pharmaceutical Galactagogues for Breast-Feeding. The Ochsner journal, 16, 511–524.

Di Pierro, F.; Callegari, A.; Carotenuto, D.; Tapia, M. M. (2008). Clinical Efficacy, Safety and Tolerability of BIO-C® (micronized Silymarin) As a Galactagogue. Acta Bio Med, 79, 205-210.

Soleimani, V, Delghandi, PS, Moallem, SA, Karimi, G. (2019). Safety and toxicity of silymarin, the major constituent of milk thistle extract: An updated review. Phytotherapy Research, 33, 1627–1638.

Biervliet, F.P., Maguiness, S.D. , Hay, D.M., Killick, S.R., Atkin S.L. (2001). Induction of lactation in the intended mother of a surrogate pregnancy: Case report, Human Reproduction,16, 581–583.

Siegel, A. B., & Stebbing, J. (2013). Milk thistle: early seeds of potential. The Lancet. Oncology, 14, 929–930.

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