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Casein Free Diet and ADHD

author image Jon Williams
Jon Williams is a clinical psychologist and freelance writer. He has performed, presented and published research on a variety of psychological and physical health issues.
Casein Free Diet and ADHD
Allergic reactions to casein, a protein in milk, can cause ADHD symptoms. Photo Credit View Stock/View Stock/Getty Images

Casein, a protein that is contained in milk and milk products, may contribute to ADHD symptoms in some children and adults. ADHD is a neurobehavioral disorder that first emerges in childhood. It is characterized by several symptoms including difficulties maintaining attention, hyperactivity and impulsivity. Symptoms almost always persist into adolescence and often continue into adulthood. Growing evidence suggests that in some cases gastrointestinal problems with digesting casein triggers physiological reactions that mimic or exacerbate ADHD.

What is Casein?

Casein is a the primary protein found in milk and in foods that contain milk such as cheese, sour cream, whey, margarine, butter, yogurt and ice cream. It can also be found hidden in many other products like soy cheese, hot dogs and lunch meats that include a casein product called caseinate. For people who are not allergic, casein has the beneficial quality of being slowly broken down, providing a steady release of amino acids into the bloodstream.

Casein Intolerance

Some people appear to have an intolerance or allergic response to casein. Casein breaks down during digestion and produces casomorphin, an opiod peptide (an amino acid chain) that acts like a histamine releaser. For most people, this peptide chain is further broken down during digestion into basic amino acids. According to HealthCentral.com, this process may not work properly for certain people, including some diagnosed with ADHD or autism. As noted at Celiac.com, Dr. Reichelt, a Norwegian researcher who has examined the effects of casein intolerance, suggests that people who lack the enzyme that breaks down proteins like casein are left with an opoid substance in their digestive system. This theoretically can produce an opium-like effect that alters perceptions and behavior and accounts for the spaciness and poor attention in ADHD.

Casein Intolerance vs. Lactose Intolerance

Casein intolerance, like lactose intolerance, involves a reaction to a substance found in milk, but the two are not related. Lactose intolerance creates temporary diarrhea, bloating and gas as a response to undigested lactose. Casein allergies are more systemic and more serious.

Symptoms of Casein Intolerance

Symptoms of casein intolerance can include diarrhea, bloating and gas, asthma, eczema and hives. There is growing concern over the possible role that casein intolerance may play in ADHD, autism and schizophrenia. People with extreme allergic responses to casein are at risk to have anaphylactic reactions and go into shock. People with extreme sensitivities can even respond to topical, non-dietary exposure to casein. For example, some finger nailpolish and make-up products contain casein and can trigger allergic reactions.


To reduce inattention, hyperactivity and other ADHD-like symptoms that may be triggered by casein intolerance, the only present treatment is to avoid exposure to foods or products that contain casein. Blood tests and skin tests are available to test for casein allergies. One can also use an elimination diet. Eliminate all milk and milk by-products from the diet for three weeks. Observe changes in behavior and attention. Reintroduce milk into the diet and note attentional and behavioral changes. If symptoms reoccur upon reintroduction of milk into the diet, then eliminate milk products from the diet permanently.


Always consult with a physician when making dramatic changes to a diet. Make sure that the losses in nutrition due to elimination of milk, including decreases in vitamin D, protein and calcium, are compensated for in the diet. The suspected links between casein and ADHD are still under investigation, and causal links should be considered preliminary. If you or your child has ADHD, seek proper medical attention to identify other possible factors and conditions that may contribute to ADHD symptoms.

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