Oleocanthal, the anti-oestrogen in olive oil
It's found in vierge or virgin olive oil: (-)-oleocanthal, a compound that has anti-carcinogenic and anti-oestrogenic properties, according to an article by pharmacologists at Jordan University of Science and Technology in the European Journal of Pharmacology. Perhaps oleocanthal supplementation can enhance the effect of anti-oestrogens such as tamoxifen.
The researchers exposed MCF-7, BT-474 and T-47D breast cancer cells to (-)-oleocanthal. All of these cell types have estradiol receptors.
The higher the concentration of the oleocanthal, the more deadly its effects on the cancer cells. The figure below on the left shows that oleocanthal kills MCF-7 cancer cells. Adding estradiol protected the breast cancer cells against oleocanthal [right], but at a high enough concentration the oleocanthal cancelled out that protective effect.
MCF-7 cells are sensitive to estradiol. In test tubes that also contain estradiol, the anti-oestrogen tamoxifen deactivates the effect of estradiol, killing the cancer cells. Oleocanthal enhances that effect of tamoxifen.
In an animal study, the researchers implanted BT-474 cancer cells in mice. In the mice that were also given 5 or 10 mg oleocanthal per kg bodyweight, the tumours stopped growing.
The researchers injected the oleocanthal directly into the small intestine. The oral human equivalent of the dose used, for an adult weighing 80 kg, would be 80-160 mg oleocanthal per day.
The researchers discovered that the oleocanthal supplementation reduced the concentration of the estradiol receptor alpha in the lab animals' tumours by forty percent. Using computer models they calculated that oleocanthal attaches itself to the estradiol receptor, as do estradiol and tamoxifen, after which the receptor breaks down.
To complete the picture: BT-474 cells do not grow well in rats and mice. The researchers had to give the mice extra estradiol to activate the tumour growth. So it's not possible to assume that the promising results of this animal study apply in the same way to humans.
"In conclusion, (-)-oleocanthal suppressed growth of [...] breast cancer cells, in part, by reducing total levels of estradiol receptor-alpha in cell culture and animal studies," the researchers wrote. "The combination of (-)-oleocanthal with the standard anti-estrogen drug, tamoxifen, showed synergistic activity."
"These findings support further evaluation of (-)-oleocanthal as a potential therapeutic option in combination with endocrine treatments in hormone-dependent breast cancer."
Eur J Pharmacol. 2017 Sep 5;810:100-11.
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Olive Oil & Extracts