If you're considering a food intolerance test, read the company's marketing materials with a critical eye. A quick scan of websites selling food intolerance tests revealed some inaccurate statements. Here are some of the most common:



Claim: Food intolerances are caused by eating a repetitive diet; this overloads the immune system and the body responds by rejecting those foods.



Reality: "The gut-associated immune system is well-equipped to deal with loads of antigenic material, and there is just no evidence that it may become overloaded by exposure to large amounts of the same antigen," said Stefano Guandalini, founder and medical director of the University of Chicago Celiac Disease Center. Although the amount you eat never causes food intolerances, "if you are intolerant you will clearly have more symptoms if you eat more of that food," added Robert Wood, professor of pediatrics and chief of pediatric allergy and immunology at Johns Hopkins.



Claim: The number of Americans with food allergies may have risen to a whopping 60 to 75 percent.



Reality: Food allergy, which is different from food intolerance, affects 5 percent of U.S. children younger than age 5 and 4 percent of older children and adults, according to the Centers for Disease Control and Prevention. As many as 1 in 3 people think they have a food allergy, but only about 1 in 28 have a food allergy confirmed by a health care official, the National Institute for Allergy and Infectious Diseases reports.



Claim: Most insurance covers food intolerance testing.



Reality: Not true.



Claim: Hair sampling is a safe and noninvasive method of revealing nutritional deficiencies.



Reality: Hair is made up of a protein, keratin, that can be analyzed to determine its mineral content. That data can be used to find out if the body is lacking in certain minerals, but it can't tell you whether you have food intolerances, allergist Lee Freund wrote in "The Complete Idiot's Guide to Food Allergies." Double-blind studies haven't shown any diagnostic value for this test.



Claim: The IgG blood test is 95 percent reliable.



Reality: The test is prone to false positives and not considered reliable by any U.S. or European allergy or immunology society.