Milk Thistle (Silybum marianum (L.) Gaertn. Family: Asterceae) has long been used in western folk medicine for nearly 2000 years and is one of the top 10 selling herbal supplements.

It is considered as a liver tonic and used to be given to women to boost lactation (milk production) although that has subsequently been disproved.

The active principle isolated from milk thistle is ‘silymarin’ which is a flavonolignan complex comprising 65 to 80% of the extract along with flavonoids, 20-35% of fatty acids and some other polyphenols. Silymarin can be broken down into the flavonolignans, silybin (silibinin), isosilybin, silychristin, silydianin and taxifolin (Kroll et al., 2007).

There are mixed views on the efficacy of milk thistle and its components. The research work with silymarin demonstrates a number of benefits from treating hepatitis and cirrhosis, to its antioxidant, anti-inflammatory and recently its chemoprotective role (Post-White et al., 2007). A series of reviews have looked at its performance and found no benefits in respect of tackling chronic liver disease (Jacobs et al., 2002), and likewise in not tackling alcoholic and hepatitis related liver disease (Rambaldi et al., 2005; 2007).

Silibinin – One Of The Key Compounds In Milk Thistle

Silibinin (silybin) itself is a mixture of two diastereomers, silybin A and silybin B, in an approximately equimolar ratio (Davis-Earles et al., 2005). Both in vitro and animal model research indicates that silibinin has hepatoprotective or antihepatotoxic properties that protect liver cells against toxins (Jayaraj et al., 2007; Al-Anati et al., 2009).

Milk Thistle has also been reviewed with a more positive emphasis on its anti-neoplastic effects (Cheung et al., 2010) such as inhibiting CYP2E1 induction which ameliorates damage due to ethanol metabolism (Brandon-Warner et al., 2010) and causing cell death in some pancreatic cancer cells (Ge et al., 2011).

Silymarin

Silymarin and most of its constituents have been proven as ‘in vitro’ antioxidants in areas such as inhibiting lipid peroxidation and reducing DNA damage (Kidd and Head, 2005). There are some highly specific studies looking at gene regulation, especially lipopolysaccharide (LPS) induced expression of IL-12 by down regulating MAPK signalling and nuclear translocation of the NF-κB p65 subunit (Lee et al., 2007), and inhibiting ultraviolet induced COX-2 expression by reducing phosphorylation (Gu et al., 2007).

In the cancer arena, early cell studies showed that silymarin could prevent in a concentration-dependent way, the TNFα-induced NF-κB activation of human histiocytic lymphoma U-937 cells (Manna et al.,1999).

In terms of diabetes control, silymarin appears to be able to regulate blood sugar levels in the type-2 form (Huseini et al., 2006).

So, Milk Thistle itself does not change the course of chronic liver disease but is claimed to reduce liver enzyme levels and can modulate immune responses, especially in modulating T-cells. It requires more rigorous trials especially human intervention studies to clearly demonstrate effects but there is clearly a lot of mileage in its action at the biochemical level.

Milk Thistle Products Available

Milk Thistle extracts are available from various suppliers and are often found in combination with other herbals.  Some might think of Milk Thistle as a weed if they saw a six foot version of it growing in their garden and didn’t really know of its importance as a herbal ingredient. Milk Thistle produces an extract containing Silymarin which is listed in the The Merck Index as a liver (hepatic) protector. It is thought to help regenerate liver cells and protect this organ from damage by toxins and viruses.

How To Prepare

Can be enjoy as an infusion; steep one teaspoon of crushed, dried seeds in a cup of boiling water for up to ten minutes, up to three times a day.

More effective as a tincture taken a few drops up to three times a day.

Cautions

• Do not use if you have any hormone-related condition or any serious medical condition without consulting a medical professional
• Do not give to any child under two years old
• Do not use while pregnant or nursing
• For over 65s, use low levels, infrequently.

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References

Al-Anati, L., Essid, E., Reinehr, R., Petzinger, E. (2009). Silibinin protects OTA-mediated TNF-alpha release from perfused rat livers and isolated rat Kupffer cells. Molecular Nutrition & Food Research 53 (4) pp. 460–6. doi:10.1002/mnfr.200800110. PMID 19156713.

Brandon-Warner, E., Sugg, J.A., Schrum, L.W., McKillop, I.H. (2010) Silibinin inhibits ethanol metabolism and ethanol-dependent cell proliferation in an in vitro model of hepatocellular carcinoma. Cancer Lett. 291 pp.120–129

Cheung, C.W., Gibbons, N., Johnson, D.W., Nicol, D.L. (2010) Silibinin–a promising new treatment for cancer. Anticancer Agents Med. Chem. 10 (3) pp. 186-195

Davis-Searles, P., Nakanishi, Y., Nam-Cheol, K., et al. (2005) Milk Thistle and Prostate Cancer: Differential Effects of Pure Flavonolignans from Silybum marianum on Antiproliferative End Points in Human Prostate Carcinoma Cells. Cancer Research 65 (10) pp. 4448-57. doi:10.1158/0008-5472.CAN-04-4662

Ge, Y., Zhang, Y., Chen, Y., Li, Q., Chen, J. (2011) Silibinin Causes Apoptosis and Cell Cycle Arrest in Some Human Pancreatic Cancer Cells. Int. J. Mol. Sci. 12, pp. 4861-4871; doi:10.3390/ijms12084861

Gu, M.; Singh, R. P.; Dhanalakshmi, S.; Agarwal, C.; Agarwal, R. (2007) Silibinin inhibits inflammatory and angiogenic attributes in photocarcinogenesis in SKH-1 hairless mice. Cancer Res. 67 (7), pp. 3483–3491.

Huseini, H.F., Larijani, B., Heshmat, R., Fakhrzadeh, H., Radjabipour, B., Toliat, T., Raza, M. (2006). The efficacy of Silybum marianum (L.) Gaertn. (silymarin) in the treatment of type II diabetes: a randomized, double-blind, placebo-controlled, clinical trial. Phytotherapy Research 20 (12) pp. 1036–9. doi:10.1002/ptr.1988. PMID 17072885

Jacobs, B.P., Dennehy, C., Ramirez, G., Sapp, J., Lawrence, V.A. (2002) Milk thistle for the treatment of liver disease: a systematic review and meta-analysis. Am. J. Med. 113(6) pp. 506-515

Jayaraj, R., Deb, U., Bhaskar, A.S., Prasad, G.B., Rao, P.V. (2007). “Hepatoprotective efficacy of certain flavonoids against microcystin induced toxicity in mice”. Environmental Toxicology 22 (5) pp. 472–9. doi:10.1002/tox.20283. PMID 17696131.

Kidd P, Head K. (2005) A review of the bioavailability and clinical efficacy of milk thistle phytosome: a silybinphosphatidylcholine complex (Siliphos®). Altern Med Rev 10  pp. 193-203

Kroll, D.J., Shaw, H.S., Oberlies, N.H. (2007) Milk thistle nomenclature: why it matters in cancer research and pharmacokinetic studies. Integr. Cancer Ther. 6(2) pp. 110-119

Lee, J. S.; Kim, S. G.; Kim, H. K.; Lee, T. H.; Jeong, Y. I.; Lee, C. M.; Yoon,M. S.; Na, Y. J.; Suh, D. S.; Park, N. C.; Choi, I. H.; Kim, G. Y.; Choi, Y. H.; Chung, H. Y.; Park, Y. M. (2007) Silibinin polarizes Th1/Th2 immune responses through the inhibition of immunostimulatory function of dendritic cells. J. Cell Physiol. 210 (2), pp. 385–397.

Manna,S.K., Mukhopadhyay, A., Van, N. T., & Aggarwal, B. B. (1999). Silymarin suppresses TNF-induced activation of NF-κB, c-Jun N-terminal kinase, and apoptosis. J. Immunology, 163(12), pp. 6800-6809.

Post-White, J., Ladas, E.J., Kelly, K.M. (2007) Advances in the use of milk thistle (Silybum marianum). Integr. Cancer Ther. 6(2) pp. 104-109 Rambaldi, A., Jacobs, B.P., Gluud, C. (2007) Milk thistle for alcoholic and/or hepatitis B or C virus liver diseases. Cochrane Database Syst. Rev. 17 (4): CD003620

Rambaldi, A., Jacobs, B.P., Iaquinto, G., Gluud, C. (2005) Milk thistle for alcoholic and/or hepatitis B or C liver diseases–a systematic cochrane hepato-biliary group review with meta-analyses of randomized clinical trials. Am. J. Gastroenterolol. 100(11) pp. 2583-2591