If there is health claims why would there be different guidelines for nutritional supplements vs pharmaceutical drugs?

http://www.nutraingredients.com/Ingredients/Omega-3s-Nutritional-oils/What-degree-of-evidence-is-required-to-make-an-EU-health-claim/?utm_source=newsletter_product&utm_medium=email&utm_campaign=18-Aug-2015&c=dC5HnbRQjql21K9TeCAWSyv5nTSeb3u1

Si il ya des allégations de santé pourquoi y aurait-il des lignes directrices différentes pour les suppléments nutritionnels vs médicaments pharmaceutiques?

http://www.hsa.gov.sg/content/dam/HSA/HPRG/Complementary_Health_Products/Overview_Framework_Policies/Health_Supplements/HSGuidelines.pdf

http://www.fda.gov/Food/DietarySupplements/QADietarySupplements/ucm191930.htm