Dr Stewart qualified as a medical practitioner in 1976 from Guy’s Hospital London and became a Member of the Royal College of Physicians in 1979.
He established his own independent medical practice in Sussex and in London in 1981 specialising in nutrition as well as homoeopathy and became a member of the Faculty of Homeopathy in 1983.
During the 1980s and 90s he was the co-author or author of many popular books on nutrition including Nutritional Medicine (Pan Books 1987 Drs. Stephen Davies and Alan Stewart), and several books with Maryon Stewart including Beat IBS Through Diet (1994 and 1997 Vermilion), Beat the Menopause without HRT (1995 Headline), Every Woman’s Health Guide (1998), and as sole author of Tired All The Time (1993 Vermilion).
He was a founding member of the British Society for Nutritional Medicine.
A number of the books have been published internationally in Bulgaria, Turkey, Russia and the US.
He has lectured widely to doctors, students of nutrition, herbal medicine and osteopathy as well as members of the public. At present he is a visiting lecturer to the University of Westminster and the European School of Osteopathy. He has appeared on local and national television and radio. In April of 2008 he appeared on BBC and ITN news responding to the reports on the adverse effects of nutritional supplements, a topic in which he has a long-standing interest.
He has worked in a consulting capacity for numerous food supplement manufacturers abroad and in the UK including Whitehall Laboratories, Boots and others. At present he has no ongoing consultancy arrangements with any food supplement or pharmaceutical company.