Lactose intolerance

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What is it

Lactose is a sugar found in the milk of humans and other mammals. The ability to digest milk occurs because lactase, an enzyme that’s produced in the small intestine, breaks down lactose into two simple sugars, which are then used by the body. When there is an insufficient amount of lactase, unabsorbed lactose moves to the colon where the bacteria cause it to ferment, leading to gastrointestinal problems.

Virtually all human infants depend on milk for survival and digest the nutrients in it, including lactose. But early in childhood, most people start producing less lactase and consequently cannot digest more than a small amount of milk. In these people, who are termed lactose intolerants or lactose maldigesters, drinking milk (especially drinking it in the absence of food) can produce uncomfortable symptoms such as gas, stomach cramps, and diarrhea within 30 minutes to two hours. (A few people, including infants, may be allergic to the protein in milk, but that’s not lactose intolerance.)

According to a recent study, only about 30 percent of all people, chiefly those who have depended historically on herding and dairy products, retain their ability to digest lactose easily or completely throughout adulthood. These include northern Europeans, some Mediterranean peoples, and descendants of both groups in the Americas, as well as certain African peoples like the Masai. Lactose intolerance occurs with varying severity in about 80 percent of Asians and Native Americans. Three-fourths of the African-American population, half of all Hispanics, and even about a fifth of white people of northwest European origin are lactose-intolerant.

There are degrees of tolerance and intolerance for milk; in fact, not all lactose intolerants have to give up regular milk. Although the ability (or loss of ability) to digest lactose is an inherited trait, drinking habits also depend on custom and preference.


  • Abdominal pain, cramps, and bloating within a few hours of consuming milk or milk products.
  • Excessive gas.
  • Diarrhea.
  • “Grumbling” abdomen and bowel.

What causes it

While some infants are born with the ailment, lactose intolerance usually develops in childhood beginning at three to five years of age. The production of lactase then steadily decreases until adolescence and remains at low levels throughout life. The ailment can also develop later in life because of chronic digestive disorders such as irritable bowel syndrome Crohn’s disease, or celiac disease. In both adults and children, a temporary form of lactose intolerance may occur owing to illness (such as gastroenteritis) or side effects of medication (such as antibiotics or NSAIDs like ibuprofen) that affect the intestinal lining and stop lactase production for a few weeks.

What if you do nothing

Lactose intolerance is not a health risk. But if you are truly lactose intolerant, symptoms can occur whenever you consume milk and other dairy products high in lactose. (However, the amount of any dairy product that you consume makes a difference in how much discomfort you experience). HOME REMEDIES Lactose intolerance cannot be cured, but once lactase deficiency has been diagnosed, there are strategies you can use to avoid or control its symptoms. The most obvious step is to eliminate all dairy products from your diet. However, this is not only difficult for most people but also often unnecessary. Instead, first follow the measures below (including turning to nondairy sources of calcium in your diet if you do reduce your consumption of dairy products).

Be sure you are truly lactose-intolerant

Bloating, flatulence, and stomach cramps aren’t always caused by lactose intolerance; it’s not a condition that develops suddenly.

You can do a simple test for lactose intolerance at home. Consume two glasses of skim milk on a vacant stomach and realize if signs like gas, bloating, and diarrhea occur throughout the following three to four hours; this means lactase deficiency is probably the cause. If so, repeat the test using lactase-treated milk. If you then experience no symptoms, you probably have a lactose intolerance. But if you have chronic gastrointestinal discomfort, you should see a doctor for further testing.

Consume small portions of milk and milk products

You can eliminate dairy products from your diet, but not only is that difficult, it often isn’t necessary. While many people can’t tolerate large portions of dairy products, they have no problems with smaller servings. In fact, research have revealed that several true lactose mal digesters (classified by laboratory checks) can consume reasonable amounts of milk and dairy products without signs, particularly if the milk is part of a meal. Whole milk causes fewer problems than skim, because its fat slows the rate of stomach emptying.

Eat dairy products along with food

This will slow the emptying of the food from the stomach into the intestine, where lactose is digested, and decrease or eliminate symptoms. This strategy allows more time for the available lactase to act upon the lactose-containing food.

Try active-culture yogurts

Fermented milk products such as yogurt with active cultures are usually easier to digest than milk. Most yogurt is low in lactose anyway, and the bacteria in it help break down what milk sugar there is. But as much as 30 to 70 percent of the lactose originally in the milk may remain in the yogurt. For lower lactose, look for yogurt that states “Live and Active Cultures” on the label or just experiment until you find a brand that agrees with you.

Cheese is all right

There should be no problems with cheese, especially hard, aged cheeses like Swiss, parmesan, and cheddar, since most lactose is removed along with the whey when the cheese is made.

Give soy milk a try

This product made from soybeans may be poured on cereal, used for cooking, and consumed as a beverage by infants and adults. Acidophilus milk or buttermilk may not be any better for people sensitive to lactose; the degree of fermentation is variable, and so lactose content also varies.

Consider using lactose-reduced and lactase products

If the other strategies don’t work for you, try lactose-reduced milk, which is available in most markets. This type of milk contains about 70 percent less lactose and tastes sweeter than regular milk.

You can also buy lactase tablets or liquid in drugstores or grocery stores and add them to the milk yourself; five drops per quart can break down over 70 percent of the milk sugar in about 24 hours (for greater reduction, let the treated milk stand for 48 to 72 hours). If you add drops to commercially treated milk, you can eliminate nearly all the lactose.

You can also swallow lactase tablets or capsules just before you consume a milk product, but that’s usually much less effective than adding drops to the milk itself.

Read labels carefully

The Food and Drug Administration (FDA) doesn’t require food companies to label their products “lactose free.” Limit or avoid foods containing milk (nonfat milk as well), lactose, casein, whey, dry milk solids, and milk curds. Lactose may be added to prepared and processed foods, including baked goods, breakfast goods, luncheon meats, salad dressings, and soups. Some artificial sweeteners may also contain lactose.

Increase the calcium in your diet

If you eliminate or drastically cut back on dairy foods, you must compensate for the lack of calcium and other essential nutrients. Rich calcium sources include leafy green vegetables, legumes, tofu, dates, prunes, fortified orange juice, canned sardines, and salmon (with the bones included). In addition, your physician may suggest calcium supplements.


There is no way known to prevent the condition of lactose intolerance, but the self-care approaches discussed above can prevent symptoms.

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