Lactose Intolerance

Lactose Intolerance

Do you often feel bloated after eating? Do you often have abdominal gas or cramps an hour after meals. If so, you may be one of 50 million Americans who are unable to digest milk products. Milk is an ideal food for an infant, but by mid to late childhood many people actually begin to lose their ability to digest this "perfect food." If you suffer from an intolerance to dairy products, this pamphlet may help answer some of your questions.

What Is Lactose Intolerance?

First of all, it is not a milk allergy, but rather an inability to digest one component of milk - lactose. Lactose is the sugar is naturally found in the milk of all mammals, but is not found anywhere else in nature. Our body cannot absorb lactose because the molecule is too large to pass through the small intestinal wall and enter our blood stream. The lactose molecule must first be split into two smaller molecules (glucose and galactose) that we can absorb. This is done by an enzyme located in the intestinal wall called lactase. As we age, some of us lose significant amounts of this enzyme, and we can no longer digest milk sugar. This common condition is called lactose intolerance. (Another name often used is lactase deficiency.)

What Are The Symptoms?

If lactose is not digested in our small intestine, it travels down to the large intestine, or colon, where it is fermented by the colonic bacteria. Just as fermentation turns grapes into champagne, lactose fermentation produces bubbles of gas which may result in abdominal bloating, gas, cramps, and diarrhea after meals. These symptoms may be mild or severe depending on the degree of lactase deficiency and the amount of lactose sugar consumed.

Who Gets Lactose Intolerance?

A lot depends upon genetics. Most people of Anglo-Saxon origin keep on producing lactase and rarely develop lactose intolerance. People of African, Asian, Mexican, Mediterranean, or Jewish descent often develop lactose intolerance after adolescence. Men and women are equally affected. This hereditary quirk is called primary lactase deficiency and cannot be prevented by any special diet or medication. This condition is not rare. It is estimated that over 50 million Americans are affected to some degree.

Less common secondary lactase deficiency is a temporary inability to digest milk products caused by damage to the inner lining of the small intestine, often due to food poisoning. As the intestine heals, the condition usually disappears in a few weeks or months.

Making The Diagnosis

An accurate diagnosis is important to make sure that your symptoms are caused by lactose intolerance and not some other more serious digestive disorder. To confirm your doctor's suspicions, a few tests may be needed. These may include:

  • The Breath Hydrogen Test. (BHT)
    When lactose is fermented by the bacteria in your colon, hydrogen gas is released, which then passes out through your lungs. During a Breath Hydrogen Test, the amount of hydrogen in your breath is measured for several hours after you drink a harmless lactose solution. No blood tests or urine samples are needed. You simply blow into a special mouthpiece and your breath is collected for analysis.

  • Lactose Tolerance Test. (LTT)
    Done much like a similarly named Glucose Tolerance Test, the LTT is not a test for diabetes. Rather, the LTT is a direct measure of lactose absorption done by taking multiple blood samples before and after drinking a harmless solution of lactose, or milk sugar. This takes about two hours.

  • Simple home test
    Here is a simple test that you can do in the privacy of your home. Avoid milk products for several days. Then, when you have a morning off, skip breakfast and drink two large glasses of skim or 1% milk (16 oz.). If digestive symptoms occurs in the next four hours, the diagnosis of lactose intolerance is likely. You should see your doctor for confirmation.

What Can Be Done?

Primary lactose intolerance is permanent. There is no prescription medication or procedure that will correct it. Therapy revolves around lactose avoidance by dietary manipulation. The strictness of the low lactose diet depends on how much the symptoms bother you and how many symptoms you are willing to tolerate.

Low Lactose Diet

Obviously, a low lactose diet restricts milk and milk products. However, many common foods contain "hidden" sources of lactose. Labels should be checked to see if foods contain milk derivatives such as casein, whey, skimmed milk, non-fat milk solids and hydrolysed whey. One common misconception is that skim milk or low-fat milk will help lactose intolerance. While these products do have reduced fat, the amount of lactose is the same as whole milk.

Fortunately, most people with lactose intolerance can tolerate small amounts of lactose and don't need to follow a diet that is completely lactose-free. Many individuals with lactose intolerance can digest the amount of lactose found in 1/2 cup of milk, but more is asking for trouble. By restricting meals which contain large amounts of lactose, many of the unpleasant digestive symptoms may be greatly diminished. Small amounts of lactose-containing foods taken several times a day may be better tolerated than a large amount consumed all at once. Foods containing lactose are better tolerated if they are taken with other foods and heated milk products such as cream soups, cocoa, custard or cooked puddings are tolerated better than unheated foods. Yogurt which is labeled "contains active culture" is low in lactose and may be enjoyed. Aged cheeses such as aged cheddar or Swiss, and processed American have reduced amounts of lactose. Butter and margarine in moderation are not usually a problem.

Over-The-Counter Remedies

While you cannot force your intestines to produce more lactase enzyme, you can limit the symptoms of lactose intolerance somewhat by taking lactase enzyme supplements with meals. Over-the-counter supplements such as Lactaid and Diary Ease can be purchased at your pharmacy without a prescription. Taken immediately before a meal, these supplements may be of benefit. You can also purchase milk at your grocery store that is pretreated to reduce lactose levels.

Getting Enough Calcium

Osteoporosis, or premature bone loss, is one of the major public health problems in the United States today, and is expected to become an even bigger problem in the next few decades as women of the "baby boomer" generation move into their fifties. Bones are not lifeless structures, but are living growing tissues that need plenty of calcium for growth and repair. Dairy products are the major sources of calcium in our diet. Current dietary guidelines recommend that all adults strive for a minimum of 1000 mg. of calcium in their diet every day. Pregnant and postmenopausal women need even more. This requires at least 4 servings every day of a low-fat dairy product such as low-fat milk, yogurt, cottage cheese, etc.

If you are lactose intolerant and unable to tolerate much milk, you will need to find other sources of calcium. Yogurt and buttermilk are worth trying, particularly if you only have a slight lactose intolerance. They are both low in lactose and also low in fat and calories. As a group, cheeses have less lactose than milk, especially the naturally aged cheeses. Lactose-free cheeses are also available.

Nondairy sources of calcium are often very helpful. Many fruit juices, such as Minute Maid Premium frozen orange juice, are calcium fortified and contain no lactose. An interesting and generally unknown source of calcium is molasses. Salmon and sardines (with bones) are good sources of calcium. Calcium-rich vegetables include the dark green vegetables such as broccoli, kale and collard greens. Spinach has much calcium, but in a form that is indigestible. Another popular source of calcium is Tums Ultra. Unlike aluminum or magnesium-based antacids, Tums is a calcium-based chewable antacid tablet that can safely be taken on a regular basis. Two tablets taken twice daily with meals provide 1200 mg. of calcium for only pennies.


Lactose intolerance is a common condition in our society, but many people never link their digestive disturbances with eating milk products. They battle the discomfort, irritation, and inconvenience caused by lactose intolerance throughout their lives. However, with proper diagnosis and awareness of the problem, most of the symptoms can be controlled. If you have any questions, ask to be referred to a registered dietitian who can help you construct a lactose restricted diet that meets your individual requirements.

Text & Images Courtesy of Three Rivers Endoscopy Center
© Dr. Robert Fusco, Three Rivers Endoscopy Center, All Rights Reserved

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