After practising for five years as a Neurologist and three years as a Neurosurgeon she started a family and moved to the UK. Fairly shortly after that her son was diagnosed autistic, which prompted an intensive study into causes and treatments of autism. It was during this time that Dr Campbell-McBride developed her theories on the relationship between neurological disorders and nutrition, and completed a second Postgraduate Degree in Human Nutrition at Sheffield University, UK. She practiced in the UK as a nutritionist and not as a medical doctor.

Dr Campbell-McBride used to run the Cambridge Nutrition Clinic. Having trained thousands of Certified GAPS Practitioners around the world, Dr Natasha has closed her clinic in order to focus on writing and teaching. As a nutritionist she has specialised in using nutritional approach as a treatment, and has become recognised as one of the world's leading experts in treating children and adults with learning disabilities and other mental disorders, as well as children and adults with digestive and immune disorders.