Dietary Supplements and Bioavailability: Looking for Some Action?

January 27, 2011

Imagine a shopper in the supplements aisle debating buying brand A over brand B. Brand A says, “More bioavailable!” Brand B does not. To most consumers, the choice seems obvious. But is it really?

Thanks to the supplements industry, more consumers are familiar with the term bioavailability. The concept seems relatively simple. If ingredients aren’t absorbed and delivered in their proper form to the target site in the body (i.e., bioavailable), they can’t do their job.

“Something that is not bioavailable is useless,” says George Burdock, PhD, president and founder of Burdock Group (Orlando, FL). “It must be absorbed and in a form that is usable and gets to the target—whether it is applied to the skin, taken internally, or inhaled.” Exceptions do exist, he notes. An insoluble fiber that’s meant to pass through the body unabsorbed would still be considered bioavailable for its intended use.

For a majority of nutrients, however, efficacy depends in part on bioavailability, starting with absorption. A fine line can distinguish whether or not an ingredient is truly bioavailable. Chromium, for instance, is best absorbed as Cr+6 but is utilized in cells as Cr+3.

Moreover, absorption and bioavailability represent only part of the picture of whether or not a product will effectively address a health condition. To determine whether a supplement truly “works,” you must examine its actual mechanisms of action in the body.

Does It Work Better?
“If you were to ask people what bioavailability really means, I think many don’t really know,” says Loren Israelsen, executive director of the United Natural Products Alliance (Salt Lake City, UT). “In our industry, a lot of time and money is spent encouraging people to take brand A over brand B. Very seldomly, though, does there seem to be a clear understanding among consumers about why a product is better or different than another.”

“I think most consumers would assume that improved bioavailability means a product works better,” says Duffy MacKay, ND, vice president of scientific and regulatory affairs, Council for Responsible Nutrition (Washington, DC).

Federico Franceschi, PhD, a senior scientist at Indena S.p.A. (Milan, Italy), agrees that many consumers automatically translate “improved bioavailability” to mean “improved efficacy,” whether or not that’s been clinically proven.

Going on bioavailability claims alone, consumers may shell out more money for a product they believe works better. Franceschi says that in a U.S. market study Indena conducted several years ago, respondents indicated a strong interest in supplements proven to be more bioavailable. Moreover, they indicated they would be willing to pay more for such products.

After all, at the end of the day, all that matters to a consumer is how well a supplement is going to improve their wellness. “The consumer doesn’t give a flying hoot if more of a supplement got into the blood,” says Anthony Almada, president and CEO of GENr8. “They just want to know if a product works better for their health.”

As supplement marketers saturate the market with bioavailability claims, bioavailability has become somewhat of a catchword.

“Bioavailability is being used as a very cheap, indirect tool to [infer] that a product is better,” Almada says.

This is where industry-wide standardization could help, says MacKay. “We don’t really have any agreed-upon measurements for making these claims. I think there could be some voluntary guidelines put forth by industry, especially related to advertising claims, stating that if you want to say that something is bioavailable, what minimum evidence would be required.”

Beware the Competition
The need for a company to separate itself from questionable absorption and bioavailability claims is one that Albion Human Nutrition (Clearfield, UT) knows well. The company has specialized in high-quality mineral amino acid chelates for more than 50 years. Like bioavailability, the word chelate is being employed more often.

In chelate form, a mineral is absorbed by the body at a higher rate. Unreacted, a mineral is an inorganic element the body can’t process. To convert into chelates, which are organic forms the body can absorb and use, when minerals enter the body, they chemically bond with organic molecules, or ligands. However, several things can inhibit or disrupt the body’s natural process of forming a chelate, says Max Motyka, MS, RPh, Albion’s director of sales and marketing.

“Inorganic minerals need to be ionized before absorption. After an inorganic mineral ionizes, it is absorbed when it binds to a special carrier at the mucosal wall of the start of the small intestine. However, these charged minerals can have their absorption interfered with by reacting with other things encountered in the gut, such as fibers, phytates, oxalates, and certain fats or lipids. When they react with these items, an unabsorbable compound is formed and passed out through the colon.”

“In addition,” he adds, “these charged minerals compete with one another for the various carriers. Certain ionized minerals compete for the same carrier and thus block the absorption of one another (zinc blocks copper absorption, and calcium can hinder zinc absorption).” Finally, conditions such as Crohn’s disease, some duodenal ulcers, and irritable bowel syndrome can also interfere with chelate formation. By providing minerals as chelates that have already been reacted, it’s added assurance that a mineral will be efficiently absorbed.

Chelates can vary in quality, however. The choice of organic material, or ligand, that a manufacturer uses to bond with the inorganic mineral atom can affect how absorbable a chelate will be. For instance, if a ligand comprises large molecules, the resulting size of the chelate molecule will be larger and typically more difficult for the body to absorb. In general, the smaller the molecule, the greater the absorption rate. Albion uses amino acids—specifically glycine—to form its chelates, which the company says is superior not only for its small molecular size but also because it is nutritionally functional.

Manufacturing processes can also dictate chelate quality. Albion’s mineral chelates are spray dried, which the company says enables a complete reaction of all of the mineral into chelate form.

Despite the dense evidence a company like Albion has to show that its mineral chelates are fully reacted and absorbable—including more than 170 peer-reviewed published studies on its products—other companies may “borrow” science or even sell mineral chelates claimed to be true chelates but that are really only partially reacted or not reacted at all, says Motyka. “There are companies that are claiming to make chelates that are just like Albion’s, and they aren’t even chelates—just blended inorganic minerals with either hydrolyzed protein or some amino acids—blended, but not reacted to form the true chelate molecule,” says Motyka.

Unfortunately, consumers may not know the difference. “Consumers, with few exceptions, are not aware of the abuse of the designation of the terms chelate or amino acid chelate. They assume that all are the same. This is a very difficult conundrum to try and solve,” says Motyka.