How can I absorb more curcumin from turmeric?

A review of curcumin's pharmacology attributes its low blood and tissue levels to three problems: poor absorption, rapid metabolism, and rapid elimination from the body².

1. Poor absorption. Curcumin is hydrophobic, meaning it doesn't dissolve well in water. Since your gut is a water-based environment, this limits how much gets absorbed through the intestinal lining.

2. Rapid metabolism. Curcumin is broken down quickly in the liver and the intestinal wall¹. The process involves glucuronidation, which attaches a sugar group to the curcumin molecule so that it can be cleared from the body.

3. Fast elimination. Whatever curcumin does make it into the blood is cleared quickly².

The result: after a 2 g oral dose of curcumin alone, serum levels in human volunteers were either undetectable or very low¹.

Strategies that have been tested

Piperine (black pepper extract) is the most studied enhancer. Shoba et al. found that 20 mg of piperine taken alongside 2 g of curcumin raised curcumin's bioavailability by 2,000% in human volunteers, and by 154% in rats, with no adverse effects reported¹. Piperine is a known inhibitor of glucuronidation — the process in the liver and gut wall that deactivates curcumin — so it gives curcumin more time in its active form.

Lipid-based formulations. Reviewers list liposomal curcumin and curcumin-phospholipid complexes among the approaches used to improve curcumin's bioavailability². Some commercial products built on these designs report much higher blood levels than plain curcumin.

Nanoparticle formulations shrink curcumin to very small particle sizes, which is meant to improve its dissolution and absorption. Curcumin nanoparticles and structural analogues of curcumin (such as EF-24) are among the other approaches that have been tried², and a later review discussed the various curcumin formulations currently available³.

Shoba et al. (1998) studied the effect of piperine on the pharmacokinetics of curcumin in rats and in healthy human volunteers¹. Curcumin on its own is poorly bioavailable because of rapid metabolism in the liver and intestinal wall, and piperine is a known inhibitor of hepatic and intestinal glucuronidation. In rats, 20 mg/kg of piperine given with a high dose of curcumin (2 g/kg) increased the serum concentration of curcumin for a short period of 1–2 hours and increased bioavailability by 154%. In humans, a 2 g dose of curcumin alone gave serum levels that were either undetectable or very low, while adding 20 mg of piperine produced much higher concentrations from 0.25 to 1 hour after the dose (P < 0.01 at 0.25 and 0.5 hours; P < 0.001 at 1 hour); the increase in bioavailability was 2,000%. The authors reported no adverse effects. The 2,000% figure is widely cited, but it comes from a single small study of healthy volunteers over a short observation period.

Anand et al. (2007) reviewed curcumin's bioavailability². Curcumin has anti-inflammatory, antioxidant, antiproliferative, and antiangiogenic activities, and Phase I clinical trials have shown it to be safe even at high doses (12 g/day) in humans, but it exhibits poor bioavailability. The major reasons for low plasma and tissue levels appear to be poor absorption, rapid metabolism, and rapid systemic elimination. The approaches that had been tried to improve bioavailability were, first, adjuvants such as piperine that interfere with glucuronidation; second, liposomal curcumin; third, curcumin nanoparticles; fourth, curcumin-phospholipid complexes; and fifth, structural analogues of curcumin such as EF-24, which has been reported to be absorbed rapidly. The authors note that, despite the lower bioavailability, curcumin's therapeutic efficacy against various human diseases has been documented, and they expect enhanced bioavailability to bring it to the forefront of therapeutic agents.

Prasad et al. (2014) reviewed how curcumin should be delivered in vivo, how bioavailable it is, how well it is absorbed, and how it is metabolized, and discussed the curcumin formulations currently available³. They note that bioavailability is perceived as one of the major problems with curcumin, and that over one hundred clinical studies have been carried out with it.

The practical takeaway from the literature: unformulated curcumin is poorly absorbed, and a plain dose gives very low blood levels. If you want systemic exposure, the approaches that have been studied are piperine-based, lipid-based, or nanoparticle-based formulations. Which formulation actually produces better health outcomes in people is a separate question that these reviews do not settle.