Anacardic acid: the anti-oestrogen in cashew nuts
A handful of cashew nuts contains about 20 mg anacardic acid, a substance that has an anti-oestrogenic effect, molecular biologists at the University of Louisville discovered. They also discovered that the anacardic acid killed hormone sensitive breast cancer cells in their test tubes.
What? Did we just say that anacardic acid is a substance? That's not quite accurate. Anacardic acid is a collective name for a number of compounds. The basic structure of anacardic acid is shown on the right above. The diagram below is of an analogue found in foods containing cashew nuts. Chemists have identified dozens of variants of anacardic acid in cashew nuts, which happen to be the best nutritional source of anacardic acid.
Products containing cashew apple juice probably contain considerably more of the stuff, going by the concentrations of anacardic acid that chemists have found in the cashew apple. [Food Chem Toxicol. 2006 Feb;44(2):188-97.]
Molecular researchers have been performing experiments with anacardic acid for a few years and have reported encouraging results. They discovered for example that anacardic acid protects the lungs of lab animals against the harmful particles in diesel exhaust fumes [Evid Based Complement Alternat Med. 2013;2013:549879.], and kills prostate cancer cells in test tubes. [Chin J Cancer Res. 2012 Dec;24(4):275-83.]
In the study that this post refers to, the researchers also did experiments with cancer cells. With breast cancer cells to be precise. The MCF-7 cell line is sensitive to estradiol; the MDA-MB-231 line is not.
The figure below shows that anacardic acid boosted the number of mono- and oligonucleosomes in the estradiol sensitive cells. In plain English: the genetic material in the oestrogen-sensitive cancer cells was destroyed when exposed to anacardic acid. The cells died.
The researchers discovered that anacardic acid didn't force estradiol out of its socket in the receptor protein. Nor did anacardic acid speed up the breakdown of the estradiol receptor by the cell.
What the substance did do is shown in the figure below. The bar chart shows you how many signals the estradiol receptor passed on to the cell's DNA.
E2 = estradiol; AnAc = anacardic acid.
As you can see, anacardic acid got in the way of estradiol, once it had attached itself to its receptor, stimulating the DNA.
The researchers do not venture an opinion on the extent to which you might be able to deactivate estradiol by including cashew nuts in your diet. The effect of 30 g cashew nuts eaten daily might just be very, very small, we fear. But who knows, maybe the effect would be strengthened if combined with other nutritional factors that have approximately the same effect, but work in a slightly different way.
Ginkgo might be such a factor. Like anacardic acid, ginkgo inhibits the functioning of the estradiol receptor. [J Steroid Biochem Mol Biol. 2006 Aug;100(4-5):167-76.] Or kelp. Or quercetin. Or...
Mol Cancer Ther. 2010 Mar;9(3):594-605.
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