April 20 2009 post. In my September 10 2007 post on how to (try to!) enhance the bioavailability of curcumin, I mentioned a study (abstract: http://tinyurl.com/2t73w5) showing that curcumin, when heated up, is more easily absorbed by the body. At the time, I didn’t have access to the full study…just the abstract. Well, two months ago (you can see how far behind I am…!), a blog reader, grazie M.!, sent the whole shebang to me. Fabuuulous. Then, a bit more recently, Sherlock did the same (grazie!). Well, well, it’s certainly better to have two copies than none…

The study focuses on a series of tests carried out on curcumin and turmeric by a team of Oklahoma researchers. I extracted what I consider to be a few interesting bits.

Here is something that any curcumin “experimenter” knows: Curcumin is practically not soluble in water at neutral or acidic pH. But the Discussion part adds that, while most of the curcumin tested did remain insoluble in water (98.5% for curcumin and 94.7% for turmeric), there was a slight increase in solubility when heat was added: from 0.21% to 2.6% with curcumin and 1.7% to 5.3% with turmeric. Not much, certainly.

But read this: However, even with these low levels of soluble curcumin, we were able to observe an 80% inhibition in protein-HNE modification. HNE modification is considered to be cytotoxic, mutagenic, and genotoxic. The abstract tells us that HNE, a major oxidation by-product, is also involved in disease pathogenesis, as we also read in this 2006 study (same authors, by the way): http://tinyurl.com/c8a8o8

The researchers believe that the water-soluble curcumin has the potential to enhance the pharmacological utility of curcumin, and this factor should be considered in clinical trials involving curcumin. HNE modification of protein could be a way in which curcumin exerts its effect.

This report deals with (1) development of procedures designed to improve solubility of curcumin, (2) development of a simple detection method for curcumin, and (3) testing the pharmacological utility of the solubilised curcumin using an in vitro assay.

In these tests, curcumin became 12 times more soluble when heated. Turmeric, in comparison, became only 3 times as soluble.

A really important point: the heating procedure did not affect curcumin stability. […] The heat treatment did not cause the curcumin to disintegrate […]. In fact, Heat treatment actually appears to protect curcumin from breaking down faster. That is a bit of more good news. Well, ok, we actually knew this from the abstract, which states that there was no significant heat-mediated disintegration of curcumin.

Discussion part: Increasing evidence points to the involvement of oxidative stress in the pathogenesis of several diseases. Curcumin is very attractive on account of the fact that it can intercept potent carcinogens such as reactive oxygen species. Of special interest is the ability of curcumin to neutralize these dangerous free radical species. Curcumin has been shown to have antimicrobial and antiprotozoal activity, antimalarial, anti-angiogenic, and antitumor effects and a variety of other biological effects.

Two of this study’s authors recently wrote a letter to the Editor of “Clinical Cancer Research” (grazie, Sherlock, and thanks also to a blog reader) urging for heat-solubilized curcumin to be tested in clinical trials. Based on the results of the Phase II clinical trial of curcumin in patients with advanced pancreatic cancer (see my Page on this topic), they suggest that the bioavailability of curcumin could be increased before oral administration to patients.

From all this, it seems that it would be helpful to heat up curcumin a bit before swallowing it. I have done that in the past, and even now, every time I make a curry, I take my curcumin capsules together with some heated spicy sauce. I have actually been doing that for years now…of course, I don’t have a curry dish every day…