DOES NOT test for food sensitivity or food intolerance. Only detects severe allergies.

These tests are expense, test only a few allergens, and need to be confirmed with a food challenge. 

RadioAllergoSorbent Test is a type of blood test used to test for a few specific allergies.  In the lab a RAST test detectsand measures the IgE reaction to suspected allergens. IgE is the antibody associated with Type I allergic response.

Type I allergies happen immediately and require treatment. Anaphylaxis can take place; an acute, systemic reaction that can prove fatal.
 Treatment is usually epinephrine, antihistamines, and corticosteroids. 

In 1989, Pharmacia Diagnostics AB replaced the RAST test with a superior test named the ImmunoCAP Specific IgE blood test. Also called  CAP RAST, CAP FEIA (fluorenzymeimmunoassay), and Pharmacia CAP.