On Nutrition: Clarifying food intolerances

A reader writes: "There are so many articles that mention dairy and gluten intolerances, but not many that talk about fructose intolerance.”

Barbara Intermill | Tribune News Service

In response to a recent column in which I mentioned that many people with lactose intolerance can tolerate small amounts of dairy foods, Theresa writes: “I don’t think you have any idea what you are talking about here. I cannot even handle a quarter cup of milk in a whole batch of biscuits. I know several who are anaphylactic even when getting a tiny bit of milk.”

Dear Theresa: You may want to get tested for milk allergy, which is much different from lactose intolerance. A true allergy to the protein in milk (as opposed to an intolerance to lactose, the sugar in milk) can indeed cause serious reactions with even very small doses of milk products. It’s important to be correctly diagnosed.

Lisa, who reads this column in the Lincoln Journal Star, writes: “I would like to see a column on the various intolerances, but especially fructose intolerance, which is what I have. There are so many articles that mention dairy and gluten intolerances, but not many that talk about fructose intolerance.”

This is also a confusing topic, Lisa. Fructose is a sugar (carbohydrate) found in fruit, honey, agave, some vegetables and foods processed with added sugars. Fructose is even found naturally in regular table sugar.

Some people lack the ability to digest fructose. And that’s where it gets tricky.

There are two types of fructose intolerance, according to the National Library of Medicine, Medline Plus. One is a rare genetic disorder called hereditary fructose intolerance, in which a person is born without the enzyme that can break down fructose. It is primarily seen in infants and children and requires a strict fructose-free diet to avoid severe liver and kidney damage.

The more common type is fructose malabsorption (formerly called dietary fructose intolerance). This condition is caused when the cells of one’s intestines cannot absorb fructose normally, leading to bloating, diarrhea or constipation, gas and stomach pain. Its cause is unknown, though our ability to digest fructose can definitely be affected by other conditions that affect the digestive system. Those include celiac or Crohn’s disease, stress and chronic antibiotic use.

Besides being difficult to diagnose (a breath test is considered the most accurate), living with fructose malabsorption is challenging. While it’s difficult to completely avoid fructose, many people get relief from following a low-fructose diet such as the low FODMAP diet, which was developed by Monash University in Australia (see www.monashfodmap.com).

Fruits particularly high in fructose, for example, include apples, pears, mangoes, cherries, figs, pears, watermelon and dried fruit. Lower fructose fruits include oranges, berries, bananas and cantaloupe.

Since fructose occurs naturally in plant-based foods, nutrient deficiencies are a big concern when these foods are limited. That’s when you may need an individualized diet plan by a nutrition professional. Find a registered dietitian nutritionist in your area at www.eatright.org.

(Barbara Intermill is a registered dietitian nutritionist and syndicated columnist. She is the author of “Quinn-Essential Nutrition: The Uncomplicated Science of Eating.” Email her at barbara@quinnessentialnutrition.com.)

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