- Digestive disorders such as celiac disease or irritable bowel syndrome
- Injuries to the small intestine
- An excess of acid in the stomach
- Foods contaminated by a toxin
- Certain types of bacteria growing in the intestine
- Recurring stress or psychological disorders
Lactose intolerance is the most well known type of food intolerance. The fact that 70 percent of the world's population has difficulty digesting lactose, the natural sugar found in milk, has led some researchers to hypothesize that lactose intolerance is in fact normal and tolerance is the abnormal condition.
Lactose is found in dairy products including milk, yogurt and cheese. Before it can be absorbed into the bloodstream, lactose must first be broken down into smaller sugar units by an enzyme called lactase that is located on the lining of the small intestine.
When the lactase enzyme is deficient, undigested lactose remains in the intestine. Fluid is drawn into the intestine by the high concentration of sugar, causing diarrhea. The unabsorbed lactose is also fermented by bacteria, producing excess gas, bloating and abdominal cramps. Although the symptoms may be similar, lactose intolerance is very different from a true milk allergy.
Nearly 75 percent of all adults lack sufficient quantities of the lactase enzyme to digest milk or other dairy products properly. Most infants are born with adequate levels of lactase but these levels seem to decline after the age of two. In the majority of cases, symptoms of lactose intolerance develop before the age of 20 and intensify over time.
The inability to digest lactose can also occur as a result of an illness or a disease that injures the intestinal lining such as Celiac disease, inflammatory bowel disease, parasitic infections and antibiotic therapy. In these cases the intolerance is often temporary and will disappear when bowel health returns to normal usually a few days to several months.
Common complaints such as nausea, cramps, bloating, gas pain and diarrhea occur 30 minutes to two hours after eating a food containing lactose. The severity of the symptoms will depend on the amount of lactose that the individual can tolerate. Some people have mild or moderate lactose intolerance and can handle some lactose, while others who have a severe intolerance must avoid all lactose containing foods and products.
Who’s at risk?
Lactose intolerance is more common among Asians, African Americans, Hispanics, Native Americans and people of Jewish descent. Individuals of these ethnic origins lose the ability to produce the enzyme lactase at about five years of age. Only five to 15% of Caucasians suffer from this highly prevalent digestive problem.
Dietary Approaches to Managing Lactose Intolerance
Living without lactose does not necessarily mean following a dairy free diet. In fact, research suggests that people with lactose intolerance who include milk and other lactose-containing foods in their diet may actually improve their tolerance to lactose.
Most people with mild or moderate lactose intolerance can consume milk in small portions (125-175 ml). Yogurt is generally well tolerated because it has less lactose than milk. The live bacteria in yogurt digest some of the lactose. Yogurt is also emptied from the stomach more slowly than milk. This gives the enzyme lactase more time to break down lactose. In general, eating solid food with lactose containing beverages improves lactose digestion because they slow the rate at which food enters the small intestine. Consuming lactose-containing foods with foods rich in soluble fibre (oats, beans, psyllium enriched breakfast cereals) may also ease symptoms of intolerance.6
Below is a list of foods according to their lactose content. Depending in the severity of your symptoms, some or all of these foods may need to be avoided.
Milk, whole, 2%, 1%, skim
Lactose Free Alternatives
Lactose is primarily found in dairy products, but it may also be present as an ingredient or component of various food products. Read labels carefully to identify sources of lactose such as milk, milk solids, sweet or sour cream, whey, lactose, curds, cheese flavours, and nonfat milk powder.
Possible food sources of lactose include breads, candy, cookies, sport energy bars, cold cuts, hot dogs, processed meats, commercial sauces and gravies, dessert mixes, some ready-to-eat breakfast cereals, frostings, salad dressings, and sugar substitutes. Individuals with severe lactose intolerance must avoid lactose in medications. Ask you pharmacist to provide a list of lactose-free equivalents.
Lactase-treated products and lactase supplements. Lactose-reduced dairy products are readily available in the dairy section of supermarkets. Products such as Lactaid' milk and Lacteeze' yogurt have been pre-treated with the lactase enzyme and are very low in lactose.
You may also choose to reduce the lactose content of dairy products yourself by using commercial lactase enzyme drops such as Lactaid' (McNeil Consumer Healthcare Inc.). Because the lactose content of dairy products can vary, you may have to adjust the number of drops you add to the food. Lactaid' is also available in capsules and should be taken upon your first bite of a lactose-containing foods. Lactaid' enzyme supplements are available in drug stores.
Vitamins and Minerals
Calcium & Vitamin D. If you avoid milk and other dairy products, your intake of calcium and vitamin D may be inadequate. Fortified soy or rice beverages should be used in place of milk since these provide the same amount of calcium and vitamin D as an equivalent amount of milk. When you purchase a soy or rice beverage, check the label to make sure the product is fortified since not all brands have added vitamins. Three cups (750 ml) of a fortified soy or rice beverage will provide roughly 900 milligrams of calcium and 300 IU of vitamin D.
Other sources of calcium appropriate for a lactose-reduced diet include yogurt, calcium fortified orange juice, leafy green vegetables, almonds and tofu. Keep in mind, however, that these foods lack vitamin D. Refer to Chapter 4 Understanding Vitamins and Minerals for lists of calcium and vitamin D rich foods.
If you do not uses fortified soy or rice beverages, take a calcium supplement with vitamin D added. Calcium citrate supplements supply 300 to 350 milligrams of calcium and calcium carbonate pills offer roughly 500 milligrams. Both will provide 100 to 200 IU of vitamin D. If you take a medication that blocks or reduces stomach acid, choose calcium citrate since the body absorbs this form of the mineral more efficiently. Depending on the amount of calcium in your diet, you may need to take a calcium pill two to three times a day.
Riboflavin. Milk provides much of our daily intake of this B vitamin, so important for energy metabolism, vision and healthy skin. If you drink fortified soy or rice beverages each day, your riboflavin requirements will be met. Other sources of the vitamin include breakfast cereals, whole grains and meat.
If you are concerned you are not getting enough riboflavin in your daily diet, take a multivitamin and mineral supplement each day. B complex formulas also provide plenty of riboflavin (25 to 100 milligrams, depending in the formula). Separate riboflavin supplements are also available in 25, 500, 100, 500 and 1200-milligram doses. You'll find these in health food and supplement stores.
International Food Information Council
National Institute of Diabetes & Digestive & Kidney Diseases
National Institute of Nutrition
The above excerpt is from "Leslie Beck's Nutrition Encyclopedia" (Penguin Canada, 2001/2003), available at bookstores across the country. The following is copyrighted and permission should be obtained from the publisher prior to any prohibited reproduction, storage in a retrieval system, or transmission in any form or means - electronic, mechanical, photocopying, or likewise.
All research on this web site is the property of Leslie Beck Nutrition Consulting Inc. and is protected by copyright. Keep in mind that research on these matters continues daily and is subject to change. The information presented is not intended as a substitute for medical treatment. It is intended to provide ongoing support of your healthy lifestyle practices.