Following a request from the European Commission, the Panel on Dietetic Products, Nutrition and Allergies was asked to provide a scientific opinion on a list of health claims pursuant to Article 13 of Regulation (EC) No 1924/2006. This opinion addresses the scientific substantiation of health claims in relation to sodium and maintenance of normal muscle function. The scientific substantiation is based on the information provided by the Member States in the consolidated list of Article 13 health claims and references that EFSA has received from Member States or directly from stakeholders. The food constituent that is the subject of the health claim is sodium. The Panel considers that sodium is sufficiently characterised. The claimed effect is “muscle function”. The target population is assumed to be the general population. The Panel considers that maintenance of normal muscle function is a beneficial physiological effect. Sodium contributes to the establishment of the membrane potential of most cells and plays a direct role in the action potential required for the transmission of nerve impulses and muscle contraction. The Panel concludes that a cause and effect relationship has been established between the dietary intake of sodium and maintenance of normal muscle function. However, the evidence provided does not establish that inadequate intake of sodium leading to impaired muscle function occurs in the general EU population. A dietary reference value for sodium has not been established, albeit it is suggested that an intake of 25 mmol/day (575 mg/day) could be set as an average requirement and the acceptable range of intake for adults should be from 25 to 150 mmol/day (575 to 3,450 mg/day). The current intake levels of sodium as sodium chloride have been associated directly with a greater likelihood of increased blood pressure, which in turn has been directly related to the development of cardiovascular and renal diseases. For these reasons, national and international bodies have set targets for a reduction in dietary sodium intakes.