Food and drink manufacturers will have to prove scientifically the health and nutritional claims they make for their products under new legislation tabled by the European Commission last week.

The legislation would prevent labels that extol virtues attributed to many foods and food supplements we eat—such as being low in energy, fat free, or high in protein—unless the labels fully comply with clear standards.

Similarly, vague terms such as “preserves youth,” “improves your memory,” or “reduces your calorie intake,” which are used as marketing …