- Is the food or ingredient defined clearly? (i.e dairy products is not specific enough).
- Is the claimed effect defined (i.e improving body shape is not defined enough, while weight reduction is and can be measured).
- What is the evidence? Interventional trials in humans, but other supportive evidence like how it works can be used. They look at all the trials for and against, and based on quality of studies.
They have a large database of authorized and non-authorized health claims undergone review for this criteria here: Food and Feed Information Portal Database | FIP
In example below how it looks like and how you can see the process for each type. Authorized health relationships for every product might be a good idea to look up according to your interests.