A Look at Lactose Intolerance

Lactose is the primary carbohydrate in milk. Cow's milkcontains 4-5% lactose, whereas human milk containsalmost twice that amount. Lactose provides 30-50% of theenergy in milk, depending on the fat content (skim vs.homogenized).A number of individuals are affected by lactose in the diet,but there is a difference between intolerance andmaldigestion.

Lactose maldigestion is "a disorder characterized byreduced digestion of lactose due to the low availability of theenzyme lactase." Lactose intolerance is "the term forgastointestinal symptoms (flatulence, bloating, abdominalpain, diarrhea, and 'rumbling in the bowel') resulting fromthe consumption of more lactose than can be digested withavailable lactase." In other words, intolerance refers to thesymptoms of the maldigestive disorder caused by aninsufficient enzyme required to hydrolyze lactose togalactose and glucose.

Genetic defects often cause a deficiency of lactase, as wellas injuries to the mucosa lining of the intestines or with age(as we age our enzyme levels decrease). When lactosemolecules remain in the intestine undigested, they absorbwater and this can cause bloating, discomfort, cramping,diarrhea, and nausea. Bacterial fermentation along theintestinal tract that produces lactic acid and gas is also acharacteristic of lactose intolerance.

It is estimated that one in three adults suffer from lactosemaldigestion and it appears to be inherited in about 80% ofthe world's population, including most Greeks, Asians, andAfricans.

Those who suffer from any discomfort after eating ordrinking milk products can consume foods labeled lactosefree or take an enzyme preparation such as Lact-Aid to aiddigestion. Do note, however, that lactose intolerance variesand the amount of lactose allowed in a diet depends on anindividual's tolerance. Some people cannot tolerate milk,ice cream, or creamed foods, but they can eat agedcheeses and yogurt (some brands are better tolerated thanothers) without difficulty. Lactose products include:

Grain Products: Breads and muffins made with milk,pancakes, and waffles; cake or cookie mixes, pie crustsmade from butter or margarine, French toast, some drycereals, and biscuits.

Fruits and Vegetables: Canned and frozen fruits orvegetables processed with lactose, buttered, creamed, orbreaded vegetables.

Milk and Milk Products: Milk (dried, evaporated, nonfat, andwhole), yogurt, ice cream, sherbet, cheese, custard,puddings, and whey and casein proteins manufactured withlactobacillus/acidophilus culture.

Meat and Meat Alternatives: Meats, fish, or poultry creamedor breaded, sausage and other cold cuts containingnonfat-milk solids, some peanut butter, and omelets andsoufflés containing milk.

Other: Instant coffees, margarine, dressings, sugarsubstitutes containing lactose, toffee, chocolate, creamedsoups, butter, cream, some cocoas, caramels, chewinggum, some vitamin-mineral supplements, some drugs,peppermint, and butterscotch.

Since calcium is a major component of manylactose-containing foods, it is vital that individuals who arelactose-intolerant receive adequate calcium from otherfoods (in fact, milk is not an ideal source of calcium, as willbe discussed in Chapter Seven). These include almonds,brazil nuts, caviar, kelp, canned salmon, canned sardines,shrimp, soybeans, and turnip greens, broccoli,strawberries, and leafy greens. Leafy greens are currentlyunder suspicion as a viable calcium source since greensare now believed to contain certain calcium binding agentsthat prevent calcium absorption.

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Brian D. Johnston is the Director of Education and Presidentof the I.A.R.T. fitness certification and education institute. Hehas written over 12 books and is a contributing author to theMerck Medical Manual. An international lecturer, Mr.Johnston wears many hats in the fitness and healthindustries, and can be reached atinfo@ExerciseCertification.com. Visit his site athttp://www.ExerciseCertification.com for more free articles.