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Rumination syndrome is an under-diagnosed chronic eating disorder, characterized by effortless regurgitation of most meals following consumption. There is no retching, nausea, heartburn, odours, or abdominal pains associated with the regurgitation, as there is with typical vomiting.

The disorder has been historically documented as affecting only infants, young children, and people with cognitive disabilities (where the prevalence is as high as 10% in institutionalized patients with various mental disabilities). Today it is being diagnosed in increasing numbers of otherwise healthy adolescents and adults, though there is a lack of awareness of the condition by doctors, patients and the general public.