A leading expert on curcuminoids has weighed into the debate over curcumin and bioavailability following a spat between suppliers over rival supplement formulations.
Dr Muhammed Majeed is founder of Sabinsa Corporation, which has been researching curcumin – a potent anti-inflammatory agent from the spice turmeric - since the mid 1990s.
He was speaking to NutraIngredients-USA after an academic on the advisory board of EuroPharma accused some suppliers of “fuzzy math” when calculating curcumin absorption and others of talking about turmeric and curcumin interchangeably, even though curcumin is only a tiny percentage of turmeric and is itself poorly absorbed.
Comparing like with like
It was important to note that curcuminoids – Curcumin (C), demethoxycurcumin (DMC), bisdemethoxycurcumin (BDMC) - in their natural state were present in the ratio 76:19:5, said Majeed. However, not all supplement formulations replicated this ratio.
“The metabolic profile [in rival Indena’s Meriva phytosome curcumin formulation] is different from unmodified natural curcumin [it is higher in DMC metabolites]. Meriva, if at all, increases the bioavailability of curcuminoid metabolites only - the glucuronide and sulfated metabolites of curcuminoids - not curcuminoids per se.
“There is no published data on the clinical efficacy of curcuminoid metabolites yet whose concentrations are purported to be increased by Meriva… the safety and efficacy data for curcuminoids gathered over the years are not applicable to this composition.”
Meanwhile, the metabolites ratio in other supplement formulations was also “in discord with the original curcuminoids ratio, thus raising concern of untested and unknown compositional effects”, he claimed.
By contrast, Sabinsa’s Curcuminoids C3 Complex reflected “the natural, unmodified composition with a very long history of safe and efficacious use”, he argued.
Bioavailability just one factor
As for which approach was best to enhance bioavailability of curcuminoids, “there was never a comparative study made between these products in a cross over fashion to assess the advantages or disadvantages of one method versus the other”, he pointed out.
However, the approach adopted by Sabinsa using black pepper extract (piperine) conserved their natural profile/ratios, he claimed.
Claims by some rivals that piperine could interfere with prescription drugs and increase the absorption of unwanted toxins were misleading given the tiny amounts used, he added.
“The 5 mg dose of co-administered piperine needed to enhance the bioavailability of curcuminoids will not enhance the absorption of drugs and toxins. More than a 20mg dose of piperine is needed for enhancing the absorption of drugs.”
However, Majeed stressed that bioavailability was only one factor firms should consider when formulating supplements containing curcumin, adding: “The current understanding of bioavailability as the benchmark of efficacy of curcuminoids may not be the correct approach, as it is very probable that unmodified curcuminoids themselves have health benefits in the body.”
What happens to curcuminoids in the body?
As to the relationship between blood levels of curcuminoids and their clinical effects, more research was probably needed, said Majeed.
“Pharmacokinetics (blood levels) and Pharmacodynamics (clinical effects) cannot be correlated due to extensive bio transformation of curcuminoids in the intestine and liver. Perhaps it is the extensive biotransformations in the intestine that may be key to curcumin's biological effect?
“The Meriva pharmacokinetic study where one could find the metabolites of minor cucuminoids (DMC and BDMC) in abundance in the blood is a clear indication that the major component in curcuminoid, that is curcumin, has undergone extensive metabolism already.
“So whether it is the so-called highly bioavailable Meriva product or so-called poorly available normal curcumoinoids, the fate of oral curcumin is the same, it gets biotransformed in the intestine and liver.”