|
Lactose Intolerance Symptoms, Causes & Treatment
|
|
|
What Is Lactose Intolerance?
Lactose intolerance is the inability to digest
significant amounts of lactose, the predominant sugar of milk. This
inability results from a shortage of the enzyme lactase, which is normally
produced by the cells that line the small intestine. Lactase breaks down
milk sugar into simpler forms that can then be absorbed into the
bloodstream. When there is not enough lactase to digest the amount of
lactose consumed, the results, although not usually dangerous, may be very
distressing. While not all persons deficient in lactase have symptoms,
those who do are considered to be lactose intolerant.
 |
| The digestive tract |
Lactose Intolerance Symptoms & Causes
Common lactose intolerance symptoms
include nausea, cramps, bloating, gas, and diarrhea, which begin about 30
minutes to 2 hours after eating or drinking foods containing lactose. The
severity of lactose intolerance symptoms varies depending on the amount of
lactose each individual can tolerate.
Some causes of lactose intolerance are well known. For instance,
certain digestive diseases and injuries to the small intestine can reduce
the amount of enzymes produced. In rare cases, children are born without
the ability to produce lactase causing lactose intolerance in babies. For
most people, though, lactase deficiency is a condition that develops naturally
over time. After about the age of 2 years, the body begins to produce less lactase.
However, many people may not experience lactose intolerance symptoms until they
are much older.
Between 30 and 50 million Americans are lactose intolerant. Certain
ethnic and racial populations are more widely affected than others. As
many as 75 percent of all African Americans and American Indians and 90
percent of Asian Americans are lactose intolerant. The condition is least
common among persons of northern European descent.
|
How Is Lactose Intolerance Diagnosed?
The most common tests used to measure the
absorption of lactose in the digestive system are the lactose tolerance
test, the hydrogen breath test, and the stool acidity test. These tests
are performed on an outpatient basis at a hospital, clinic, or doctor's
office.
The lactose tolerance test begins with the individual fasting (not
eating) before the test and then drinking a liquid that contains lactose.
Several blood samples are taken over a 2-hour period to measure the
person's blood glucose (blood sugar) level, which indicates how well the
body is able to digest lactose.
Normally, when lactose reaches the digestive system, the lactase enzyme
breaks down lactose into glucose and galactose. The liver then changes the
galactose into glucose, which enters the bloodstream and raises the
person's blood glucose level. If lactose is incompletely broken down, the
blood glucose level does not rise and a diagnosis of lactose intolerance
is confirmed.
The hydrogen breath test measures the amount of hydrogen in the breath.
Normally, very little hydrogen is detectable in the breath. However,
undigested lactose in the colon is fermented by bacteria, and various
gases, including hydrogen, are produced. The hydrogen is absorbed from the
intestines, carried through the bloodstream to the lungs, and exhaled. In
the test, the patient drinks a lactose-loaded beverage, and the breath is
analyzed at regular intervals. Raised levels of hydrogen in the breath
indicate improper digestion of lactose. Certain foods, medications, and
cigarettes can affect the test's accuracy and should be avoided before
taking the test. This test is available for children and adults.
The lactose tolerance and hydrogen breath tests are not given to
check for lactose intolerance in babies and very young children who are suspected
of having the condition. A large lactose load may be dangerous for very young
individuals because they are more prone to dehydration that can result
from diarrhea caused by the lactose. If a baby or young child is
experiencing symptoms of lactose intolerance, many pediatricians simply
recommend changing from cow's milk to soy formula and waiting for lactose
intolerance symptoms to abate.
If necessary, a stool acidity test, which measures the amount of acid
in the stool, may be given to check for lactose intolerance in babies and
young children. Undigested lactose fermented by bacteria in the colon creates
lactic acid and other
short-chain fatty acids that can be detected in a stool sample. In
addition, glucose may be present in the sample as a result of unabsorbed
lactose in the colon.
|
Lactose Intolerance Treatment
Fortunately, lactose intolerance is relatively
easy to treat. No treatment exists to improve the body's ability to
produce lactase, but lactose intolerance symptoms can be controlled through diet.
Young children with lactase deficiency should not eat any foods
containing lactose. Most older children and adults need not avoid lactose
completely, but individuals differ in the amounts and types of foods they
can handle. For example, one person may suffer symptoms of lactose intolerance
after drinking a small glass of milk, while another can drink one glass but
not two. Others
may be able to manage ice cream and aged cheeses, such as
cheddar and Swiss, but not other dairy products. Dietary control of lactose
intolerance depends on each person's learning through trial and error how
much lactose he or she can handle.
For those who react to very small amounts of lactose or have trouble
limiting their intake of foods that contain lactose, lactase enzymes are
available without a prescription. Lactase enzyme tablets are available to
help people digest foods that contain lactose. The tablets are taken with
the first bite of dairy food. Lactase enzyme is also available as a
liquid. Adding a few drops of the enzyme will convert the lactose in milk
or cream, making it more digestible for people with lactose intolerance.
Lactose-reduced milk and other products are available at most
supermarkets. The milk contains all of the nutrients found in regular milk
and remains fresh for about the same length of time, or longer if it is
super-pasteurized.
|
How Is Nutrition Balanced?
Milk and other dairy products are a major source
of nutrients in the American diet. The most important of these nutrients
is calcium. Calcium is essential for the growth and repair of bones
throughout life. In the middle and later years, a shortage of calcium may
lead to thin, fragile bones that break easily, a condition called
osteoporosis. A concern, then, for both children and adults with lactose
intolerance, is getting enough calcium in a diet that includes little or
no milk.
In 1997, the Institute of Medicine released a report recommending new
requirements for daily calcium intake. How much calcium a person needs to
maintain good health varies by age group. Recommendations from the report
are as follows:
| Age group |
Amount of calcium to consume daily, in
milligrams (mg) |
| 0-6 months |
210 mg |
| 6-12 months |
270 mg |
| 1-3 years |
500 mg |
| 4-8 years |
800 mg |
| 9-18 years |
1,300 mg |
| 19-50 years |
1,000 mg |
| 51-70+ years |
1,200 mg |
Also, pregnant and nursing women
under 19 need 1,300 mg daily, while pregnant and nursing women over 19
need 1,000 mg.
In planning meals, making sure that each day's diet includes enough
calcium is important, even if the diet does not contain dairy products.
Many nondairy foods are high in calcium. Green vegetables, such as
broccoli and kale, and fish with soft, edible bones, such as salmon and
sardines, are excellent sources of calcium. To help in planning a
high-calcium and low-lactose diet, the following chart lists some common
foods that are good sources of dietary calcium and shows about how much
lactose the foods contain.
Recent research shows that yogurt with active cultures may be a good
source of calcium for many people with lactose intolerance, even though it
is fairly high in lactose. Evidence shows that the bacterial cultures used
in making yogurt produce some of the lactase enzyme required for proper
digestion.
Calcium and Lactose in Common Foods |
| |
Calcium Content |
Lactose Content |
Calcium-fortified orange juice,
1 cup |
308-344 mg |
0 |
Sardines, with edible bones,
3 oz. |
270 mg |
0 |
| Soymilk, fortified, 1 cup |
200 mg |
0 |
| Salmon, canned, with edible bones, 3 oz. |
205 mg |
0 |
| Broccoli (raw), 1 cup |
90 mg |
0 |
| Pinto beans, 1/2 cup |
40 mg |
0 |
| Orange, 1 medium |
50 mg |
0 |
| Tuna, canned, 3 oz. |
10 mg |
0 |
| Lettuce greens, 1/2 cup |
10 mg |
0 |
| |
| Dairy Products |
| Yogurt, plain, low-fat, 1 cup |
415 mg |
5 g |
| Milk, reduced fat, 1 cup |
295 mg |
11 g |
| Swiss cheese, 1 oz. |
270 mg |
1 g |
| Ice cream, 1/2 cup |
85 mg |
6 g |
| Cottage cheese, 1/2 cup |
75 mg |
2-3 g | | |
| Adapted from Manual of Clinical Dietetics. 6th ed.
American Dietetic Association, 2000; and Soy Dairy Alternatives.
Available at: http://www.soyfoods.org/.
Accessed March 5, 2002. |
Clearly, many foods can provide the calcium and other nutrients the
body needs, even when intake of milk and dairy products is limited.
However, factors other than calcium and lactose content should be kept in
mind when planning a diet. Some vegetables that are high in calcium (Swiss
chard, spinach, and rhubarb, for instance) are not listed in the chart
because the body cannot use their calcium content. They contain substances
called oxalates, which stop calcium absorption. Calcium is absorbed and
used only when there is enough vitamin D in the body. A balanced diet
should provide an adequate supply of vitamin D. Sources of vitamin D
include eggs and liver. However, sunlight helps the body naturally absorb
or synthesize vitamin D, and with enough exposure to the sun, food sources
may not be necessary.
Some people with lactose intolerance may think they are not getting
enough calcium and vitamin D in their diet. Consultation with a doctor or
dietitian may be helpful in deciding whether any dietary supplements are
needed. Taking vitamins or minerals of the wrong kind or in the wrong
amounts can be harmful. A dietitian can help in planning meals that will
provide the most nutrients with the least chance of causing discomfort.
|
What Is Hidden Lactose?
Although milk and foods made from milk are the
only natural sources, lactose is often added to prepared foods. People
with very low tolerance for lactose should know about the many food
products that may contain lactose, even in small amounts. Food products
that may contain lactose include
- bread and other baked goods
- processed breakfast cereals
- instant potatoes, soups, and breakfast drinks
- margarine
- lunch meats (other than kosher)
- salad dressings
- candies and other snacks
- mixes for pancakes, biscuits, and cookies
Some products labeled nondairy, such as powdered coffee
creamer and whipped toppings, may also include ingredients that are
derived from milk and therefore contain lactose.
Smart shoppers learn to read food labels with care, looking not only
for milk and lactose among the contents but also for such words as whey,
curds, milk by-products, dry milk solids, and nonfat dry milk powder. If
any of these are listed on a label, the product contains lactose.
In addition, lactose is used as the base for more than 20 percent of
prescription drugs and about 6 percent of over-the-counter medicines. Many
types of birth control pills, for example, contain lactose, as do some
tablets for stomach acid and gas. However, these products typically affect
only people with severe lactose intolerance.
|
Summary
Even though lactose intolerance is widespread,
it need not pose a serious threat to good health. People who have trouble
digesting lactose can learn which dairy products and other foods they can
eat without discomfort and which ones they should avoid. Many will be able
to enjoy milk, ice cream, and other such products if they take them in
small amounts or eat other food at the same time. Others can use lactase
liquid or tablets to help digest the lactose. Even older women at risk for
osteoporosis and growing children who must avoid milk and foods made with
milk can meet most of their special dietary needs by eating greens, fish,
and other calcium-rich foods that are free of lactose. A carefully chosen
diet, with calcium supplements if the doctor or dietitian recommends them,
is the key to reducing lactose inolerance symptoms and protecting future health.
Keeping on Top of Your Condition
Keeping in tune with your disease or condition not only makes treatment less intimidating but also increases its chance of success, and has been shown to lower a patients risk of complications. As well, as an informed patient, you are better able to discuss your condition and treatment options with your physician.
A new service available to patients provides a convenient means of staying informed, and ensures that the information is both reliable and accurate. If you wish to find out more about HealthNewsflash's innovative service, take the tour.
|
Additional Resources
American Dietetic Association (ADA)
216 West Jackson
Boulevard
Chicago, IL 60606-6995
Phone: (312) 899-0040
Fax:
(312) 899-1979
Internet: www.eatright.org
International Foundation for Functional Gastrointestinal Disorders
(IFFGD)
P.O. Box 170864
Milwaukee, WI 53217
Phone:
1-888-964-2001 or (414) 964-1799
Fax: (414) 964-7176
Email:
iffgd@iffgd.org
Internet: www.iffgd.org
|
|
|
|
