Milk Thistle Compound Provides Protection Against Lung Cancer

June 30, 2006

"Our research findings suggest that milk thistle (with active compound silimarin) could inhibit lung cancer growth and progression�?We expect that after supplement consumption a sufficient level of silimarin must be achieved in blood circulation/lung to have an anticancer effect," said lead researcher Rana Singh.

Lung cancer is the most common form of cancer worldwide with over 1.2m new cases diagnosed annually, according to the European School of Oncology. It has one of the lowest survival rates with only 25 per cent of patients surviving more than one year after diagnosis (England and Wales).

It should be stressed that the new research, published in the Journal of the National Cancer Institute (Vol. 98, pp. 846-85), did not use milk thistle dietary supplements, but pure silimarin, the active component in milk thistle.

"Milk thistle extract dietary supplements generally contain 80 per cent silymarin, a flavonolignan mixture; and silymarin contains approximately 40 per cent silimarin," explained Singh.

"Therefore, we expect about 32 per cent (w/w) silimarin in milk thistle dietary supplements," she said.

The researchers divided 90 mice into six groups and injected 75 mice with cancer-causing urethan e (cancer development in two to three weeks) and 15 mice with a saline solution (control).

After two weeks of eating a normal diet, the urethane-treated mice (five groups of 15) were fed a diet supplemented with different doses of silimarin (zero, 0.033, 0.10, 0.33, 1.0 per cent).

After 18 weeks, the silimarin supplemented group had between 32 and 38 per cent less tumours than the urethane-only group, across all the dose range. After 29-weeks, the silimarin supplemented group had between 64 and 70 per cent less tumours than the urethane-only group, across all the dose range.

Mice that received the 1.0 per cent silimarin supplement had 93 per cent fewer large tumours than the urethane-only group.

In terms of cancer spread, the tumours in the silimarin supplemented mice had between 41 and 74 per cent fewer cells that tested positive for proliferation (spread) markers.

The formation of blood vessels (angiogenesis) was also found to be reduced in the silimarin groups, with reductions up to 89 per cent recorded.

"Our most clinically relevant observation was that silimarin prevented tumours from growing beyond a small size in a dose-depended fashion," said the researchers.

"We believe that this inhibition is due, at least in part, to the inhibitory effect of silimarin on angiogenesis."

The mechanism behind the effects is not clear, but the researchers suggest that the flavanone may act on the expression of two enzymes (iNOS and COX-2), as well as the vascular endothelial growth factor (VEGF), which promote tumour angiogenesis.

The mechanism continues to be studied, said the researchers.

The authors caution that the animal model of lung cancer, while similar, does not mirror human lung cancer.

A comparable dose in a 70 kg human would be in the range of about 2 to 20 grams per day for the three lower doses, said Singh.

While this may sound like a lot, Singh said that research has indicated such doses of silimarin are not toxic.

"A recent study in human prostate cancer patients suggest that silimarin consumption up to about 6.7 g/day (equivalent to 20 g/day silimarin-phytosome in three equal doses) does not show any significant adverse health effect.

"This study is still continuing with escalated doses of silimarin to find out the maximal tolerated dose in the patients," said Singh.

Milk thistle (Silybum marianum) has been used for a long time as a food in Europe. Young leaves are used in salads, the stalks eaten like asparagus, and the heads boiled like artichoke.

Milk thistle is best known for its health benefits related to diseases of the liver.

From:  July 2,  2006, No 339 Longevity News  For Further Information on Young Again's Services and Products Go to http://youngagain.com/