Life requires two basic things to survive: oxygen and adequate essential nutrients. Except in rare circumstances, these nutrients come from foods. Some nutrients provide energy and many are required for the hundreds of chemical reactions necessary to grow, repair and maintain body tissues.

Virtually every aspect of life has some connection with food, from culture and family traditions to the ways we socialize and nurture one another. Sadly, for some individuals, a food allergy or food intolerance can affect a person’s relationship with food and subsequently, many of the social aspects related to food.

The University of Michigan describes a food allergy as “an immune response (hives, rash, shortness of breath, swelling, etc.) to a food that a person consumes.” A food allergy affects the immune system, with small amounts of the offending food or ingredient triggering symptoms that can even be severe or life-threatening. The Food and Drug Administration now requires the identification of nine allergens on food product labels, including milk, eggs, peanuts, tree nuts (such as almonds, walnuts, cashews), fish, shellfish, soy, wheat and newly added sesame.

Food intolerances do not test positive using standard allergy diagnostic tests. Still, they can have many of the symptoms of food allergies. Besides intestinal symptoms, recent research focuses on a broader range of symptoms that resolve when the food culprit is eliminated from the diet. For example, nonceliac gluten intolerance may have symptoms similar to allergies, including skin, joint and respiratory disorders. Inflammatory symptoms resulting from gluten can take some time to resolve.

Question: Which foods are most likely to trigger food sensitivities?

Answer: The three most common food intolerances are related to lactose, casein and gluten.

Lactose and casein are found in milk. Lactose is also used in some medications; consult your pharmacist. An over-the-counter lactase pill can help eliminate issues with lactose intolerance.

Remaining gluten-free is challenging. Gluten is found in grains such as wheat, rye, barley and triticale. Still, it is in many recipe ingredients, such as soy and oyster sauces. Spices and other foods may contain trace amounts of gluten when processed in a facility that handles wheat-containing products. Reading the food label ingredient list becomes a must. Also, gluten- free food only meets the gluten-free definition based on the amount of gluten in a single-label serving.

Eating out is the biggest challenge. A couple of tips: Don’t be shy about telling the server or chef you have a gluten allergy so they can tell you what menu items are gluten-free. Also, eat before going to a potluck to help stay gluten-free.

Joannie Dobbs, Ph.D., C.N.S. and Alan Titchenal, Ph.D., C.N.S. are retired nutrition faculty from the Department of Human Nutrition, Food and Animal Sciences, College of Tropical Agriculture and Human Resources, University of Hawaii at Manoa.