The primary challenge formulators face when working with curcumin, an extract of turmeric root, is ensuring that the bioactive compounds are absorbed significantly upon ingestion. With this in mind, the industry has experimented with a number of pharmacokinetic innovations, a plethora of which are available commercially.
 
 A recent clinical trial found that a new dried colloidal suspension formulation used in the curcumin supplement ingredient Turmipure Gold, manufactured by Naturex, was shown to have the strongest bioavailability for both conjugated and unconjugated curcuminoids when compared to three other capsules and one liquid formulation, which included a standard turmeric powder extract, a phytosome formulation, and a piperine formulation, and the liquid formulation.
 
However, in terms of total curcuminoid absorption levels, both Turmipure Gold and a liquid micellar formulation containing 6% curcuminoids (NovaSOL, manufactured by Aquanova AG) saw significantly higher bioavailability than the other formulations.
 
The study enrolled 30 healthy men and women, and was a randomized, open-labeled, crossover trial. Each of the participants sequentially consumed single oral doses of each of the given formulations, which included various doses: a 1500 mg turmeric extract, a 1515 mg piperine-curcuminoid combination, a 1000 mg dose of phytosome formulation, and a 300 mg dose of the dried colloidal suspension formula.
 
“Orally administered turmeric native compounds have a low intestinal absorption, and most are excreted unchanged,” the authors of the study said, adding that the bioactive compounds in curcumin are hydrophobic, and have low solubility in water. “Due to the combination of poor oral absorption, rapid metabolism, and rapid elimination from the systemic circulation, systemic concentrations of unconjugated curcumin do not exceed the low micromolar concentration in humans even after oral doses less than or equal to 12 grams.”
 
The authors of the study noted that in addition to total curcuminoid levels, it was important to look at certain bioactive molecules rather than the entire content, due to multiple compounds within curcumin exerting unique properties which are linked to health benefits. These individual bioactive molecules include not just total curcumin, but also DMC and BDMC the latter two of which are unconjugated curcumin. In total, the researchers broke down blood concentrations of 15 curcuminoid metabolites in the study participants,  due in large part to the fact that it hasn’t been determined which of the curcumin compounds have the greatest scope of antioxidant activity in the human body.
 
“To date, there is no consensus whether the activities of turmeric extract are due to unconjugated curcumin, DMC, or BDMC, or to their phase I and phase II metabolites,” the authors wrote, adding that evidence is especially mixed on BDMC across at least 22 trials to date.
 
“In conclusion, enhanced bioavailability of turmeric curcuminoids is desirable in view of their encouraging various health benefits but challenged by their poor absorption and rapid metabolism […] Not all curcuminoid formulations were found to deliver equivalent pharmacokinetic profiles. Nevertheless, the new colloidal suspension TPG was revealed to be particularly promising in that 300 mg was sufficient to demonstrate bioequivalence to over 1500 mg of the standard turmeric extract.”