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 a health claim in relation to L-ornithine and contribution to the regulation of the urea cycle. 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 L-ornithine. The Panel considers that L-ornithine is sufficiently characterised. The claimed effect is “ornithine helps to normalize liver function”. The Panel assumes that the target population is the general population. In the context of the proposed wordings, the Panel assumes that the claim refers to the role of L-ornithine in the regulation of the urea cycle. The Panel considers that contribution to the regulation of the urea cycle is a beneficial physiological effect. L-Ornithine is a metabolic intermediate in the urea cycle and is synthesised de novo in the human body. No evidence has been provided for a contribution of dietary L-ornithine to the claimed effect. The Panel concludes that a cause and effect relationship has not been established between the consumption of L-ornithine and contribution to the regulation of the urea cycle.