This guideline was coordinated by the World Health Organization (WHO) Evidence and Programme Guidance Unit, Department of Nutrition for Health and Development. Dr Pura Rayco-Solon, Dr Lisa Rogers and Dr Juan Pablo Peña-Rosas oversaw the preparation of this document. WHO acknowledges the technical contributions of the following individuals (in alphabetical order): Dr Andrea Bosman, Ms Hala Boukerdenna, Dr Carmen Casanovas, Dr Camila Chaparro, Dr Maria Nieves García-Casal, Dr Viviana Mangiaterra, Ms Zita Weise Prinzo and Mr Gerardo Zamora. We also thank the peer-reviewers Ms Solange Durao, Dr Tran Khanh Van and Ms Terrie Wefwafwa.

We would like to express our gratitude to Dr Susan Norris from the WHO Guidelines Review Committee Secretariat and members of the Guidelines Review Committee for their technical support throughout the process. Thanks are also due to Ms Alma Alic from the Department of Compliance and Risk Management and Ethics, for her support in the management of the conflicts of interests procedures. Ms Jennifer Volonnino, from the Evidence and Programme Guidance Unit, Department of Nutrition for Health and Development, provided logistic support.

WHO gratefully acknowledges the technical input of the members of the WHO Steering Committee for Nutrition Guidelines Development and the WHO guidelines development groups, especially the chairs of the meeting concerning this guideline, Ms Deena Alaasor and Dr Maria Elena del Socorro Jefferds.