Regulations vary between countries and often permit vague claims Functional foods are foods that claim to improve wellbeing or health.1 The health claim may be implicit (“rich in vitamin C”), or vague (“strengthens the body's defence system”), but invariably the product is presented with the suggestion of a benefit. Sales of such products are huge and growing. What ingredients do such foods contain—and who safeguards the truth of claims? Many functional foods contain added vitamins, minerals, and other essential nutrients. Some of these added nutrients indeed promote health: folic acid reduces the risk of neural tube defects, table salt with potassium reduces blood pressure, and polyunsaturated fatty acids reduce the risk of heart disease. But other claims are more dubious—for example, that zinc lozenges protect against colds or that drinks rich in vitamin C protect against cardiovascular disease. Functional foods may also contain non-nutritive ingredients. Examples of effective non-nutritive ingredients are sugar alcohols in chewing gum, which reduce risk of dental caries; plant stanols and sterols, which lower low density lipoprotein cholesterol (although effects on heart disease remain to …