A gluten-free casein-free diet (or GFCF diet) eliminates dietary intake of the naturally occurring proteins gluten

Gluten

Gluten is a protein composite found in foods processed from wheat and related grain species, including barley and rye...

 (found most often in wheat

Wheat

Wheat is a cereal grain, originally from the Levant region of the Near East, but now cultivated worldwide. In 2007 world production of wheat was 607 million tons, making it the third most-produced cereal after maize and rice...

, barley

Barley

Barley is a major cereal grain, a member of the grass family. It serves as a major animal fodder, as a base malt for beer and certain distilled beverages, and as a component of various health foods...

, rye

Rye

Rye is a grass grown extensively as a grain and as a forage crop. It is a member of the wheat tribe and is closely related to barley and wheat. Rye grain is used for flour, rye bread, rye beer, some whiskeys, some vodkas, and animal fodder...

, and commercially available oats

OATS

OATS - Open Source Assistive Technology Software - is a source code repository or "forge" for assistive technology software. It was launched in 2006 with the goal to provide a one-stop “shop” for end users, clinicians and open-source developers to promote and develop open source assistive...

) and casein

Casein

Casein is the name for a family of related phosphoprotein proteins . These proteins are commonly found in mammalian milk, making up 80% of the proteins in cow milk and between 60% and 65% of the proteins in human milk....

 (found most often in milk

Milk

Milk is a white liquid produced by the mammary glands of mammals. It is the primary source of nutrition for young mammals before they are able to digest other types of food. Early-lactation milk contains colostrum, which carries the mother's antibodies to the baby and can reduce the risk of many...

).
Despite an absence of scientific evidence, the Autism Research Institute

Autism Research Institute

The Autism Research Institute , established in 1967 by Bernard Rimland, is a San Diego, California, based nonprofit that funds research and provides information on autism and autism spectrum disorders. Stephen M...

 recommends the GFCF diet as a treatment for autism

Autism

Autism is a disorder of neural development characterized by impaired social interaction and communication, and by restricted and repetitive behavior. These signs all begin before a child is three years old. Autism affects information processing in the brain by altering how nerve cells and their...

 and related conditions. A study by the University of Rochester found "eliminating gluten and casein from the diets of children with autism had no impact on their behavior, sleep or bowel patterns".

The study was performed with a small group - 14 children - and they selected only ones without any gastrointestinal (GI) issues.