Industry Should Reform Bioavailability Claims, Supplier Says

September 21, 2010

A review of a selection of published ingredient studies has concluded that many bioavailability ingredient claims are often weakened by a large variance between the amounts of active ingredients subjects absorbed. The review, published in the January issue of Natural Medicine Journal, looked at studies done on CoQ10 and carotenoids.

A review of a selection of published ingredient studies has concluded that many bioavailability ingredient claims are often weakened by a large variance between the amounts of active ingredients subjects absorbed. The review, published in the January issue of Natural Medicine Journal, looked at studies done on CoQ10 and carotenoids. It was led by ingredients supplier BioActives LLC (Worcester, MA).

"We noticed that in many studies, the intersubject variance--the difference between what individual subjects absorbed--was very large," told the study's lead author, Daniel Kagan, PhD, a managing partner at BioActives, to Nutritional Outlook. (He disclosed that a BioActives study was among the studies reviewed.)

Kagan says that many of the reviewed studies failed to adequately discuss such variances, if they occurred, and their implications. For instance, he says, in many cases when a study concluded that an ingredient was more bioavailable, the ingredient was actually only more bioavailable in a minority of subjects.

Wrote Kagan et al., "The results are reported based on statistically significant differences between the mean scores in different treatment groups...Some studies circumvent statistics altogether by singling out the one data point of the best absorber and [promoting] it as [being] 'up to X times more bioavailable.' While these claims are mostly based on statistically significant differences between treatment groups, they can be misleading, as the average of all the data may include subjects who were poor absorbers as well as those who were super-absorbers."

Or, as Kagan says, "The few super-absorbers are the ones that can drive the results."

As a result of what Kagan calls incomplete reporting, "it is difficult for physicians and consumers to compare the bioavailability claims of different formulations," wrote Kagan et al. Moreover, Kagan points out, if a consumer purchases a product labeled highly bioavailable when data actually showed it is highly bioavailable for some of the subjects and not highly bioavailable for others, then the consumer wouldn't know whether he or she is likely to be represented by the group that does or doesn't absorb the supplement well.

By contrast, Kagan et al. note that, "The pharmaceutical industry has a concrete definition of bioavailability and uses explicit methods for evaluating the bioavailability of drugs...In fact, bioavailability studies are an important part of the information necessary to support an FDA approval."

Kagan et al. suggest that the industry instead adopt new, standard terms when making bioavailability claims that indicate the likely percentage of consumers for whom an ingredient is bioavailable. If a bioavailability claim likely applies to 85% of consumers, an ingredient/product could then be deemed reliably bioavailable. If a claim applies to 99% of consumers, an ingredient/product could be deemed universally bioavailable. (The authors offer a method for calculating these criteria.)

The reviewers concluded, "The benefits derived from nutritional supplements are directly related to their bioavailability, yet the dietary supplement industry lacks well-defined standards to ensure adequate bioavailability."

Kagan adds that improving the accuracy of bioavailability claims may improve the chances that consumers will select supplements that are bioavailable for them. "Think of all the return customers companies are losing because the consumer did not realize the benefit of the supplement," he says.

For more information, e-mail Daniel Kagan at dankagan@earthlink.net.