The blog reader (thanks, PvM!) who sent me all the cytogenetic studies on myeloma also provided me with a few studies on the cancer-killing compounds found in olive oil. Even though I have already dealt with the anticancer properties of olives, see my page on oleanolic acid, which is extracted mainly from olive leaves, I hadn’t seen this particular study, published in November 2008 in “The Journal of Nutrition” (full study: http://tinyurl.com/cprfho) and carried out by an Italian team from the University of Perugia, the lovely provincial capital of one of my favourite Italian regions, Umbria.
The researchers examined the effect of a virgin olive oil phenol extract (PE) on proliferation, the cell cycle distribution profile, apoptosis, and differentiation of the human promyelocytic cell line HL60. Phenols, incidentally, are rather acidic chemical compounds. Curcumin, for instance, is a phenolic compound from turmeric; so is capsaicin (<chilli peppers). And olive oil happens to be full of antioxidant phenolic compounds.
An interesting point: there is a clear association between the consumption of olive oil and a reduced risk of certain types of cancer: breast, ovary, prostate, colon and larynx. Olive oil has also been shown to suppress spontaneous liver tumorigenesis in mice and reduce skin carcinogenesis when applied topically both before and after exposure of mice to UV light. Hmmm, I didn’t know that…well, well…
In this study, the researchers incubated the leukemic cell line HL60 with PE, the above-mentioned olive oil extract (a complex mixture of phenols)…and, abracadabra!, after a few days, 100% were NECROTIC, even at rather low concentrations. One hundred percent! Put simply, PE not only inhibited proliferation of the leukemic cells but also killed them.
The researchers state (my emphasis) that Another important result of the present investigation is that PE can induce differentiation in HL60 cells. Although several previous studies showed that phenols present in wine and tea can induce differentiation in promyelocytic cell lines, as well as in other systems, to the best of our knowledge, our results are the first to show such an effect exerted by phenols from olive oil. Important, indeed!
Another significant excerpt: the researchers state that there is still no evidence that olive oil can protect against leukemia. But, they add, In the present study, a clear anticancer activity of some phenolic compounds isolated from olive oil was demonstrated. Such activity was evident at phenol concentrations relatively higher than those observed in vivo after a normal daily intake of olive oil; however, it is possible that the regular low life-time intake of olive oil results in an overall protective effect.
I grew up in Italy, which has a national obsession, rightly so!, with high quality (=extra virgin) olive oil. I can give up lots of things, but it would be almost impossible for me to live without olive oil. It’s more important to me than chocolate! But, thinking back on all the years that I lived in the U.S. and Canada, I almost certainly used very little olive oil, and certainly not the high-quality stuff that we get now from Italian friends who have their own organic olive grove. It made me wonder…
Of course there are a lot of Italians with leukemia and myeloma, so I don’t mean to imply that my years without the protective effect of olive phenols led me to develop MGUS and then SMM. But wouldn’t it be interesting (impossible, I know!) to see how many Italian leukemic patients have a high versus low olive oil intake? Oh well, just a silly thought…
Anyway, this was certainly an interesting study. Another related one, sent by the same blog reader (thanks again, PvM!), examines the metabolism of olive oil phenols in humans. Since the full study is available online (http://tinyurl.com/cfjl6f), I will mention only that we absorb a great deal of the olive oil we swallow…and this bit of information could be useful for a future olive oil/curcumin experiment, since, as we know, curcumin dissolves in fats and oil. To be honest, the thought of experimenting with olive oil had crossed my mind some time ago, and I know some blog readers already mix curcumin with olive oil, but I hadn’t considered it very seriously because of the omega 6/3 ratio. But now…well, we shall see…
Interesting titbit: a 2007 Spanish study (see: http://tinyurl.com/dbfg7q) showed that the phenolic compounds in olive oil, just like curcumin, killed eight strains of H. pylori (see my page on H.pylori and MGUS), even three that were resistant to antibiotics. Based on their results, these researchers think that olive oil might be used as a chemopreventive agent for peptic ulcer or gastric cancer, but this bioactivity should be confirmed in vivo in the future. Extraordinary…
P.S. my new blog banner is a photo I took this morning of the view from our bedroom window.