EU legislation on nutrition and health claims made on foods (Regulation (EC) No. 1924/2006) specifies that health claims should be only authorised for use in the Community after a scientific assessment of the highest possible standard is carried out by the European Food Safety Authority (EFSA). This paper focuses on the scientific substantiation of health claims within the context of the EU Regulation. The evaluation of the substantiation of health claims is carried out by the EFSA Scientific Panel on Dietetic Products, Nutrition and Allergies (NDA). The EFSA has published extensive guidance to assist applicants in the preparation of applications for authorisations of health claims. This guidance summarises the general principles applied by the NDA Panel in the evaluation of health claims, including the scientific criteria for substantiation, as well as the scientific requirements for the substantiation of specific health claims. To date, the EFSA NDA Panel has concluded that a wide range of health claims has been substantiated. These include claims for many well-established functions of nutrients, as well as beneficial effects of foods and food constituents on a range of body functions. In addition, claims have been substantiated on the role of nutrients in growth and development of children and on the effects of nutrients and food constituents on reduction of risk factors for disease. EFSA evaluations and guidance have made an important contribution to the understanding of the scientific substantiation of health claims which will help to set new directions for research and will guide future innovation.