What Turmeric Curcumin Can and Cannot Do

Skepticism that clinical effects could be achieved in humans with turmeric has historically revolved around the apparent poor bioavailability of the spice. In other words, people just seem to poop it out without absorbing any. Give people a turmeric extract and you can detect the bright yellow turmeric pigment curcumin in their feces but not in their bloodstream. One study even found undetectable blood levels after giving people eight grams of straight curcumin—that’s like chowing down on more than a cup and a half of turmeric. But this was before advanced analytical techniques were developed. Using more sensitive detection methods you can pick up curcumin in people’s bloodstreams within a half hour of eating a meal infused with even just a teaspoon of turmeric that lasts at least eight hours.

The amounts of curcumin floating around in their blood after the meal was miniscule, on the order of a millionth of a gram, but the levels of curcumin metabolites were much higher. There are enzymes in our liver and intestinal lining that can process and alter turmeric compounds and maybe it’s these degradation products that are doing the heavy lifting in the body. And the less turmeric gets absorbed, the more it’s available to affect our microbiome down in our colon. That’s another potential explanation of the paradox between the poor bioavailability yet apparently rich pharmacological effects. Maybe, in fact, too rich. Curcumin has been categorized as both a PAIN and an IMP, a “panassay interference compound” and an “improbable metabolic panacea.” In other words, it seems a little too good to be true, to the point of potentially causing false positive results by interfering with some of the tests in a laboratory setting. The proof, however, is in the pudding.

In recent years, more than fifteen thousand articles have been published in the medical literature about curcumin. It was first isolated more than a century ago, but out of the thousands of experiments, only a few hundred were clinical studies involving actual human participants, but promising effects have been observed for a wide variety of conditions.

I would suggest incorporating turmeric into one’s diet rather than taking curcumin or turmeric extract supplements. Curcumin is just one of many different components of the whole-food spice. In vitro studies have shown that curcumin-free turmeric—that is, turmeric with the so-called active ingredient removed—can sometimes work as well as turmeric, which can be superior to curcumin alone, for example here killing off cancer cells in a petri dish. Rare cases of liver toxicity have also been reported with high dose supplements that far exceed what could conceivably be achieved through diet. Residues of toxic solvents may also be present in extracts. Out of 35 turmeric supplements analyzed on the U.S. market, one exceeded lead safety levels. They don’t say which one it was, but the supplement claimed to have 61 mg of curcuminoids along with 3 mg of piperine per capsule if anyone wants to try to sleuth it. The vibrant yellow color of turmeric is one of its selling points, so why not just add the bright yellow compound lead chromate to make it look even yellower? This appears to be a widespread practice in Bangladesh, and indeed the only samples exceeding safety limits in a test of 32 turmeric products bought in Boston were the ones imported from Bangladesh, so one might want to stick to turmeric imported from elsewhere, or just buy the root fresh.