No Milk Thistle in ESTROsmart or ESTROsmart Plus Formulas

Q: Q: Lorna, I've noticed that you do not have milk thistle your new ESTROsmart and ESTROsmart Plus formulas. Can you tell me what your reasons are?

A: Many women have emailed me to ask why I have taken milk thistle out of my new product ESTROsmart. You may remember the story about my grandmother who died of breast cancer. Because I have a very strong genetic history of breast cancer, I am constantly researching how foods, nutritional supplements, lifestyle and hormones affect breast cancer prevention and treatment. One of the reasons why I originally formulated Estrosmart was to help reduce the risk of breast cancer not only for myself, my daughters and my granddaughter but also for every woman. I later decided to add DIM (a plant nutrient for breast health) as new human research became available showing its benefits.

Originally, I thought milk thistle would be beneficial because of its ability to support liver function. The liver is involved in hormone detoxification and conjugation of estrogens. I have been examining the research over the years involving milk thistle and its effect on breast cancer cell function, as many of you know because you have emailed me about milk thistle and potential breast cancer risks in the past. Several test tube studies showed that breast cancer cells may be inhibited when exposed to milk thistle, particularly silymarin, which is a mixture of polyphenolic flavonoids isolated from milk thistle. Unfortunately, as the research moved to animals (rodents), the findings have not been so positive. One study published in the medical journal Carcinogenesis performed in rodents found that milk thistle stimulated the growth of mammary tumors. Researchers at the University of Minnesota found that silymarin had an estrogen-like effect on human MCF-7 breast cancer cells. We still do not have any human studies in women using milk thistle for breast cancer prevention or treatment. Only one pilot study has been performed in 40 premenopausal women using a combination of curcumin, rosemary, milk thistle, shizandra, and dandelion. The researchers found no statistical differences in hormones in the women over a five-month period other than a decrease in early follicular stage androgens. But, to date, no human research has looked at milk thistle's effect on women with breast cancer.

Because I was launching my new SMART products, I decided to formulate ESTROsmart and ESTROsmart Plus with Vitex without milk thistle. I feel the situation could be like that with soy products whereby when soy was first introduced, research was positive as to its effect on breast cancer cells, but as the research matured, we discovered that soy had a reverse effect especially in North American women who are estrogen-dominant. Due to ongoing research, we do not recommend soy products for women with breast cancer anymore and we have gone even further and only recommend fermented soy for all women (tempeh, miso, soy sauce, natto). Until human research in women is performed and specifically looks at the components of milk thistle including silymarin and silibinin, I feel we should heed the caution of the BC Cancer Agency to avoid milk thistle if you have breast cancer. Removing milk thistle from ESTROsmart will not affect its action as curcumin, rosemary, I3C, DIM and d-glucarate all have liver support action and help to halt the conversion of healthy estrogens to cancer causing-estrogens. You can read more about these ingredients at

Rodent studies:
"Enhancement of mammary carcinogenesis in two rodent models by silymarin dietary supplements." Malewicz B, Wang Z, Jiang C, Guo J, Cleary MP, Grande JP, Lu J. Carcinogenesis. 2006 Sep;27(9):1739-47. Epub 2006 Apr 5.

"Consumption of silibinin, a flavonolignan from milk thistle, and mammary cancer development in the C3(1) SV40 T,t antigen transgenic multiple mammary adenocarcinoma (TAg) mouse." Verschoyle RD, Brown K, Steward WP, Gescher AJ. Cancer Chemother Pharmacol. 2008 Jul;62(2):369-72. Epub 2007 Oct 2.

Test Tube Studies:
"Silibinin induces protective superoxide generation in human breast cancer MCF-7 cells." Wang HJ, Jiang YY, Wei XF, Huang H, Tashiro S, Onodera S, Ikejima T. Free Radic Res. 2010 Jan;44(1):90-100.

"Silibinin prevents TPA-induced MMP-9 expression by down-regulation of COX-2 in human breast cancer cells." Kim S, Kim SH, Hur SM, Lee SK, Kim WW, Kim JS, Kim JH, Choe JH, Nam SJ, Lee JE, Yang JH. J Ethnopharmacol. 2009 Nov 12;126(2):252-7. Epub 2009 Aug 26.

"Silibinin inhibits translation initiation: implications for anticancer therapy." Lin CJ, Sukarieh R, Pelletier J. Mol Cancer Ther. 2009 Jun;8(6):1606-12. Epub 2009 Jun 9.

"Silibinin prevents TPA-induced MMP-9 expression and VEGF secretion by inactivation of the Raf/MEK/ERK pathway in MCF-7 human breast cancer cells." Kim S, Choi JH, Lim HI, Lee SK, Kim WW, Kim JS, Kim JH, Choe JH, Yang JH, Nam SJ, Lee JE. Phytomedicine. 2009 Jun;16(6-7):573-80. Epub 2009 Jan 31.