Washington, May 24 (IANS): About 30 percent of Americans believe they have food allergies. However, the actual number is far smaller -- closer to five percent, according to a recent study.

The study, commissioned by the National Institute of Allergy and Infectious Diseases (NIAID), says the higher figure is due in large part to the unreliability of the skin test that doctors commonly use to test for food allergies.

Christopher Love, assistant professor of chemical engineering at Massachusetts Institute of Technology (MIT) believes he has a better way to diagnose such allergies.

His new technology can analyse individual immune cells taken from patients, allowing for precise measurement of the cells' response to allergens such as milk and peanuts.

Using this technology, doctors could one day diagnose food allergies with a simple blood test that would be faster and more reliable than current tests, says Love.

The NIAID study found that in the US, six to eight percent of children under four, and four percent of people five or older, have at least one food allergy: milk, peanuts, eggs and soy being the most common allergens.

Food allergies occur when the body's immune system mistakes a protein in food for something harmful.

This triggers an allergic response that can include rashes, hives, difficulty in breathing or gastrointestinal distress. Some allergies can provoke life-threatening shock, which requires immediate treatment.

Patients suspected of having food allergies usually undergo a skin test, which involves placing small quantities of potential allergens under the skin of the patient's arm.

If the patient's blood has antibodies specific to that allergen, immune cells release histamines that cause itching and redness in the spot where the allergen was placed.

Doctors can also perform blood tests that directly measure the presence of particular antibodies in the patients' blood.

However, one drawback of both these tests is that the presence of antibodies to a particular allergen does not necessarily mean that the patient is allergic to that substance, leading to false positive results.

Love's new technology takes a different approach. Instead of detecting antibodies, his system screens the patient's immune cells for small proteins known as cytokines.

Immune cells such as T cells produce cytokines when an allergic response is initiated, attracting other cells to join in the response, said an MIT release.

The findings were published in the Journal of the American Medical Association.