For approximately 30 to 50 million Americans, consuming a food or product containing lactose, the sugar in milk, produces some degree of unpleasant digestive symptoms, according to the Cleveland Clinic. Many acquire lactose intolerance over a period of years, but some become lactose intolerant after a surgical procedure, including gastric bypass surgery. Limiting or avoiding dairy products may help to prevent symptoms, but patients should also read product labels carefully to identify sources of hidden lactose.
Lactose Basics
The body needs lactase, a digestive enzyme, to break down lactose, the sugar in milk and other dairy products, including buttermilk, lactose-reduced milk, evaporated milk, condensed milk, ice cream, whipped topping, cheese and hot chocolate mixes. Since lactose-intolerant individuals lack sufficient amounts of the lactase enzyme, the milk sugar and extra fluid pass into the large intestine to be broken down by bacteria into lactic acid. The lactic acid causes irritation and a laxative effect, producing mild to severe symptoms such as bloating, diarrhea, abdominal cramping and gas.
Lactose in Medications
Approximately 20 percent of prescription medications, including birth control pills or oral contraceptives, contain lactose, according to the Cleveland Clinic. About six percent of over-the-counter medications, including some vitamins minerals and drugs for acid reflux and gas, also contain lactose. However, only severely lactose-intolerant individuals react to the relatively small amounts of lactose in these medications.
Reading Food Labels for Hidden Lactose
While refrigerated or frozen milk and dairy products may seem to be the primary sources of lactose, many packaged foods contain some lactose as well. Reading food labels carefully helps to detect hidden sources of lactose, including those made from casein, whey, butter, cheese, curds, milk by-products, dry milk solids or dry milk powder. Lactose intolerant individuals should also limit or avoid foods containing the terms breaded, creamed, cheese-flavored, sour cream-flavored or milk chocolate.
Foods Containing Hidden Lactose
Unlikely sources of hidden lactose include processed grains -- breads, rolls, biscuits, muffins, pancakes, waffles, cakes, cookies, crackers and cereals -- and breaded meat, vegetables or fish. Some processed meats, including lunch meat, hot dogs and sausage, as well as some egg substitutes also contain lactose. Any product that contains cream, sour cream or cheese, including cream soups, macaroni and cheese, dried potato mixes, chips, salad dressings and dips, also contain lactose, as do desserts and candies made of milk products, including pudding, sherbet, mousse, milk chocolate or caramel candies.
Beverages with Lactose
Beverages that contain lactose include instant iced tea, instant coffee, Ovaltine and chocolate drink mixes. Milk-based instant breakfast mixes, meal replacements and protein shakes and powders made from whey concentrates or casein. Lactose-intolerant individuals should look for similar products made from soy or whey isolates, neither of which contains lactose. Some cordials and liqueurs also contain lactose.
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