Clinical testing design for functional food claims The link between study design and strength of evidence
For substantiating health claims for functional foods, a causal relationship must be established between the consumption of the functional food and the claimed health benefit. This causal relationship needs to be obtained in thetarget population. Randomised controlled trials (RCT) and, when available, systematic reviews and meta-analyses of RCTprovide the strongest evidence. However, even when data from RCT are available, not all studies are equal for substantiating specific claims. In fact, the choice of the claim to be made should be the first step of study design. In thiscontribution, a selection of practical aspects related to study design that have direct implications for claim substantiationare addressed and illustrated by concrete examples.