et al., 2006). The range of allowed claims, even with documented evidence, is too narrow. Sanders commented that consumers and health care providers should be provided with truthful information so that they can make informed choices about probiotics.


Experiments within a well-controlled laboratory or clinical setting may indicate that a particular bacterium is a highly effective probiotic, but in reality the probiotic may not be effective if its bioactivity is lost before it is able to confer any health benefit. Many studies have shown that probiotic bacteria lose their activity over time if they are placed in foods that have not been correctly designed to accommodate those bacteria, according to David Julian McClements. There has been a dramatic increase in probiotic viability studies over the past decade, with many studies showing appreciable reductions in probiotic viability during food storage or during transit through the human GI tract. For example, Priya et al. (2011) reported a 108- to 109-fold decrease in the number of viable probiotic organisms by the time they reached the small intestine.

Delivery System Design

McClements’s research program revolves around the design of encapsulation systems, that is, structured delivery systems that encapsulate, protect, and deliver bioactive compounds to an appropriate site of action within the GI tract. While most of his work is with nutraceuticals, he asserted that the same systems are amenable to utilization for the encapsulation and delivery of live bacteria. In the previously mentioned Priya et al. (2011) study, in addition to researchers observing a dramatic decrease in the number of viable bacteria reaching the colon, they also observed substantial improvement upon encapsulating the bacteria in a multilayer polymer coating (see Figure 5-3).

McClements noted two key considerations to keep in mind when designing delivery systems for probiotics. First, whether a probiotic delivery system will work or not depends on the strain of bacteria, the nature of the delivery system, and the kind of food in which the bacteria is being delivered. He remarked that the tremendous variability observed in the results of probiotic viability studies reflects variation in these factors. Second, foods are low-profit-margin materials. The food industry wants the simplest, cheapest, and most robust solutions to any given problem. Yet, because they are difficult to make and require complicated processing operations,


14 This section summarizes the presentation of David Julian McClements.

The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement