NIZO food research has developed and validated challenge models that can assess the effect of foods and ingredients in healthy people by introducing a controlled stressor. This meets the requirement of proving the effect of foods on health in groups that represent the intended consumers.
Among EFSA’s guidelines is listed that the “specific study group(s) in which the evidence is obtained is representative of the target population for which the claim is intended.” Until now, no validated biomarkers are available for gut health and resistance to infections, and often proof was found by intervention trials in populations that were not considered relevant. Alternatives for challenge models include randomized controlled trials in populations at risk for infection, for instance people who are travelling to a country with a high risk for traveler’s diarrhea or children in developing countries. A major disadvantage is that due to variation in subjects and pathogens, very large numbers of subjects are needed.
NIZO scientists have developed and validated a challenge model with an attenuated ETEC vaccine in which a relatively small group of healthy subjects receive either a placebo or a functional food ingredient. After 2 weeks subjects are challenged with an ETEC vaccine. This attenuated ETEC strain is a spontaneous mutant unable to produce toxins. After the challenge, ETEC counts are determined in stools, and infectious diarrhea and gastrointestinal symptoms are recorded.
Sandra ten Bruggencate, group leader Nutrition at NIZO emphasizes that this approach gives relevant primary outcomes. “pathogens like ETEC are seen as relevant stressors by EFSA and we have already successfully carried out various randomized clinical trials in healthy volunteers for clients”.
The next step, the development of a Rhinovirus challenge model, is already on its way. “the first intervention trial is planned for early 2013 in collaboration with the University Medical Centre Radboud in Nijmegen”.
According to Henk van Loveren, Professor at Maastricht University and expert on this topic, “the ETEC and Rhinovirus challenge models are very promising in substantiating health claims in the area of gut health and immunity”.