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The question: My doctor told me I have lactose intolerance. Which foods, besides dairy, do I need to avoid?

The answer: If your lactose intolerance is not severe, you may not need to give up all types of dairy products. If your intolerance is mild to moderate, chances are that you can tolerate yogurt, and perhaps some milk if it's consumed with food, without feeling symptoms. On the other hand, if you have severe lactose intolerance, you will have symptoms with even small amounts of dairy.

Lactose intolerance, as I am sure you are aware, is the inability to digest and absorb lactose, the natural sugar found in milk and milk products. For lactose to be absorbed from the intestine, it first must be split into two smaller sugar units with the help of a digestive enzyme called lactase.

Symptoms occur because the undigested lactose passes from the small intestine into the large intestine where it's fermented by gut bacteria. This causes the release of excess gas, bloating and discomfort. Undigested lactose also draws water into the colon, which may cause diarrhea.

So, back to your question: What foods contain lactose and should be avoided? Lactose is found in milk, yogurt, cream, butter, ice cream and cheese. But it's also in some breads and baked goods, pancake mixes, ready-to-eat breakfast cereals, instant soups, candy, cookies, salad dressings, deli meats, drink mixes and margarine.

If you have severe lactose intolerance, you'll need to stay away from dairy products and non-dairy foods with milk ingredients. That will require label reading to see if there is dairy or lactose on the ingredient list. Words that indicate lactose include whey, curds, milk byproducts, dry milk solids and milk powder. Lactose can also be hidden in prescription and over-the-counter medications, so check with your pharmacist.

Luckily, most people with mild or moderate intolerance can handle small portions of milk – up to 1/2 cup at a time. Drink milk with meals, rather than on an empty stomach, to slow digestion and reduce the chances of symptoms. You can also buy lactose-reduced milk at the grocery store. These products have been pretreated with lactase and are 99-per-cent lactose-free. You can reduce the lactose content of dairy products yourself by using lactase enzyme supplements, such as Lactaid, sold in drug stores.

You can also replace milk with a soy beverage; they are lactose-free and supply the same amount of protein, calcium, vitamin D, B12 as milk. Just be sure to buy unflavoured or unsweetened to avoid added sugars.

Yogurt is usually well tolerated because the live bacteria cultures contain lactase, which breaks down some of the lactose during storage and when it's eaten. Hard cheeses, such as cheddar, Swiss and Parmesan, have small amounts of lactose and generally cause no symptoms.

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