Brewster started her career specializing in children and young adults with developmental disabilities. She specializes in metabolic disorders, gastrointestinal disorders, specialized tube feedings, dysphagia, autism, behavior, sensory processing, attention-seeking behavior, oral motor skills, and eating disorders. Since starting, she has included all aspects of restrictive diets and supplements.
She is a member of Dietitians in Integrative and Functional Medicine. She earned their 2013 Excellence in Practice Award. Brewster served as a professor at the University of Bridgeport's MAters in Nutrition. She is the former Director of Nutrition at the Atkin's Center for Complementary Medicine in New York City. She claims that medication is "symptom suppression. Addressing nutrition will help mitigate some of the long term side effects while assisting in true healing. That food is medicine."
She believes that autism is "an accumulation of brain pollution. It's just the culmination of chemical/ body burden. And just wreaking havoc with the immune systems, the endocrine systems and the neurological systems of little tiny bodies that are coming into this world with a high body burden. And meeting a very adulterated food supply, whose parents have grown up on adulterated food supply and have lots of exposure to a lot of neurotoxic chemicals that were introduced into our environment post World War II."
At Autism One, she speaks on the subjects of children's health and nutrition:
"There is always hope. The body, when given the right macro and micro nutrients, has great capacity to heal. Like the old adage, you cannot keep doing something the same way and expect different results, so it goes with what we put into our bodies. Nutritional biochemistry dictates the high regard we should have for the food we put into ourselves and our unique biochemical response to food. When we are aware of the intricacies of our gastrointestinal tract and the gut-brain connection, we are more likely to respect what we feed ourselves, our children, and how we take care of Mother Earth, which is the source of what feeds us all. "