Study may clarify effects of diet pill's ingredient

Editor's note: CNN's Dr. Sanjay Gupta answers medical questions submitted by e-mail on "Your Health," which airs at 2:30 p.m. EDT Saturdays. Questions and answers are posted on CNN.com after the show.

Q: Is the diet pill Metabolife safe? -- Tara from Charlotte, North Carolina

A: The issue is a complicated one, with many plot twists dating back to before 1997 when the Food and Drug Administration moved to regulate one of Metabolife's key ingredients, ephedra, and then backed off.

The makers of Metabolife claim studies have shown it is safe when used at the recommended doses.

They have even asked the FDA to regulate them and their industry.

Earlier this summer, the Department of Health and Human Services announced plans to review existing science on ephedra -- the ingredient that is really at the heart of the controversy.

The review, which should be ready by the fall, should help clarify what is known about epheda's uses, doses and side effects.

Q: Can you tell me more about food allergies, especially those related to cow's milk and peanuts in young toddlers and infants? -- Shekar from New Jersey

A: A food allergy occurs when your immune system responds aggressively to particular food protein and releases histamine into your system.

Histamine, a powerful chemical, causes many reactions: For example, it causes blood vessels to enlarge and nasal tissue to swell and itch.

It can also affect the respiratory system and the gastrointestinal tract.

Symptoms, which can appear almost immediately or up to two hours after the food is eaten, include tingling in the mouth, swelling of the tongue or throat, hives or skin rashes, vomiting, abdominal cramps, diarrhea, difficulty breathing and/or a drop in blood pressure.

Severe reactions, called anaphylaxis, can be life-threatening.

Food allergies affect 8 percent of American children, and six foods account for 90 percent of these allergies: milk, eggs, peanuts, wheat, soy and tree nuts such as walnuts, pecans and almonds.

The best way to treat a food allergy is to avoid the foods that cause reactions.

The good news is that, unlike adults, many children will outgrow their allergies.

"Ask Dr. Gupta" is not intended to address specific questions concerning individual cases. CNN does not directly or indirectly practice medicine or provide medical advice, and nothing contained in the responses of CNN through its correspondents is a substitute for medical advice, diagnosis or treatment. Always contact your doctor if you need medical advice or treatment, or have any questions regarding a medical condition.