Dr Alan Stewart qualified as a doctor at Guy's Hosital, London, in 1976 and spent five years specializing in hospital medicine. He became a member of the Royal College of Physicians (MRCP UK) and worked at the Royal London Homoeopathic Hospital, qualifying as an MF Hom.

He is a founding member of the British Society for Nutritional Medicine and Medical Advisor to the Women's Nutritional Advisory Service.

He is author of Tired All the Time (Optima 1993) and co-wrote the bestselling book Nutritional Medicine. He has also contributed to other books including Beat PMT Through Diet, Beat Sugar Cravings, The Vitality Diet, Inside Science, The Migraine Revolution and the academic book Post Viral Fatigue Syndrome.

He lectures and writes articles on various aspects of health, contributes to radio programmes and has appeared on many TV magazine programmes.

He lives in Lewes, Sussex, with his wife, nutritional advisor Maryon Stewart, and their four children.