Q. When I eat certain foods, I don't feel well. After I eat them, I get gassy and bloated, and sometimes I just feel exhausted. Is this a food allergy? How can food allergies be tested?

A. Intestinal gas and bloating can be symptoms of either a food intolerance or a food allergy. A food intolerance can occur if you lack the ability to digest a certain food. Lactose intolerance, for example, which is very common in the Asian population, happens when a person can't digest the sugar in milk products because he or she lacks the enzyme to do so. To determine if you have lactose intolerance, you can avoid ingestion of milk products and see if your symptoms go away, drink lactaid milk, or take enzymes that assist with lactose digestion.

A food allergy occurs when your body makes antibodies (immune cells) to a certain food, or a certain food group. To determine if you have a food allergy you can do an elimination-challenge test, or you can get a blood test. Some food allergies give you an immediate reaction to a food, known as an IgE mediated reaction. However, there is a type of delayed food allergy reaction, known as an IgG mediated reaction, which is much more difficult to identify since symptoms can occur 24 to 72 hours later.

An elimination-challenge test, which you can do on your own, has helped many of my patients determine which foods are big offenders and which aren't. It gives you feedback from your body after you eat a food that you're allergic to. Here's how to take the test:

1. For one week, avoid eating the most common food allergens: dairy products, beef, wheat, gluten, eggs, corn, peanuts, shellfish, and soy. Also add any other foods you suspect you're allergic to.

2. After one week, choose one of the foods or food groups you avoided (the one that you most miss in your diet), and begin testing it by eating it three to four times a day.

3. For three days, watch for symptoms of an adverse reaction such as digestive distress, joint pain, migraines, headaches, puffy eyes, a runny nose, water retention, hives, fatigue, depression, mood swings, canker sores or achy, weak muscles.

4. After three days, test another food or food group you avoided, and again watch for symptoms.

Continue testing all the foods or food groups you avoided, one by one, in this manner. Once you've identified what foods you're allergic to, eliminate them from your diet for at least three months. You may be able to reintroduce certain foods after this time.

Laurie Steelsmith is a naturopathic physician and licensed acupuncturist in Honolulu, as well as author of "Natural Choices for Women's Health," published by Random House. You can reach her and read her past columns at www.DrSteelsmith.com. This column is for information only. Consult your health provider for medical advice.