Lactose Intolerance Diet

Lactose intolerance is a condition caused by the inability to digest lactose, a sugar found in milk. The lactose intolerance diet is a diet designed to treat the uncomfortable symptoms that can result from undigested lactose.

No single person originated the lactose intolerance diet. Physicians treating symptoms of lactose intolerance developed diet recommendations through observation and trial and error by their patients.

Symptoms of lactose intolerance include nausea, bloating, abdominal pain or cramps, abundant gas, and diarrhea. These symptoms usually begin anywhere from 30 minutes to 2 hours after eating a food that contains lactose. Symptoms of lactose intolerance can be uncomfortable and may temporarily interfere with daily activities. However, they do not harm the digestive system, and lactose intolerance does not progress to any other disease or disorder.

Lactose intolerance is an extremely common condition. It rarely develops before age six and is caused by a genetically programmed decline in lactase. This decline begins around age two, the age when most infants have finished the transition from breast milk to solid food. In some people this decline continues to the point where they develop lactose intolerance symptoms, usually by late childhood or early adulthood. Lactose intolerance is strongly linked to race and ethnicity. People of Northern European ancestry have the lowest rate of lactose intolerance, about 5%. In Hispanic, Jewish, and Southern European populations, the rate is about 70%, and it is thought to be 90% or more in Asian and African populations. Worldwide, the inability to digest lactose is much more common than the ability to digest it. Although the symptoms are similar, lactose intolerance is not the same as cow's milk intolerance. Cow's milk intolerance is a food allergy that produces an allergic reaction. Only about 3.4% of Americans have cow's milk intolerance.

The degree to which people are lactose intolerant varies widely. Some people can drink a glass of milk daily without developing unpleasant symptoms. Others can drink only small amounts of milk at a time and have fewer symptoms if milk is mixed with food. Some people can eat cheese, ice cream, or yogurt but cannot drink milk. A few people are 100% lactose intolerant, and even the smallest amount of lactose will produce unpleasant symptoms.

Calcium and lactose in common foods

SOURCE: National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, U.S. Department of Health and Human Services. https://www.niddk.nih.gov/healthinformation/digestive-diseases/lactose-intolerance/eating-dietnutrition (accessed on April 14, 2018).

Although the greatest quantities of lactose are found in milk and dairy products, milk is used in the preparation of many processed foods such as chocolate bars, puddings, and soups. Food labels must list all of the ingredients in processed foods. Lactose intolerant individuals should look for words on the label that indicate the presence of lactose, such as milk, condensed milk, whey, curds, milk byproducts, or dry milk solids.

Besides dairy products, lactose is found in other unlikely places such as:

The amount of lactose found in these hidden sources is not enough to affect most people, but for the severely lactose intolerant, it can be enough to cause symptoms.

Many individuals diagnose themselves as lactose intolerant using an elimination diet. However, people who think they may be lactose intolerant should see their physician. Symptoms of lactose intolerance can be quite similar to other more serious and sometimes progressive diseases such as celiac disease (a gluten intolerance), Crohn's disease, giardia (a parasitic infection of the bowel), and inflammatory bowel disease. Lactose intolerance can be diagnosed by giving an individual lactose and then measuring changes in the sugar (glucose) level in their blood. In lactose intolerant individuals, lactose is not broken down into the sugars that can be absorbed from the intestine. Therefore, the level of glucose in the blood will be lower than expected. Lactose can also be diagnosed by a hydrogen breath test.

Lactose intolerance is treated by eliminating lactose from the diet beyond the level where it produces symptoms. Alternately, enzymes such as LACTAID or Dairy Ease can be added to milk 24 hours before drinking. These enzymes pre-digest lactose and can eliminate 70%–99% of lactose from milk and dairy drinks. Lactose-reduced milk is available at many supermarkets—all LACTAID and Dairy Ease milk is 70% lactose-free except for non-fat LACTAID, which contains no lactose. When eating other foods that contain lactose, LACTAID and Dairy Ease capsules are available that can be taken at the same time that an individual begins eating. These capsules contain enzymes to help digest lactose.

Since dairy products are a primary source of calcium, people who eliminate milk, cheese, yogurt, and other dairy products must adjust their diet to get enough calcium. Calcium is critical to building and maintaining strong bones and teeth and is needed for metabolic processes such as muscle contraction and nerve impulse transmission.

The U.S. Institute of Medicine (IOM) of the National Academy of Sciences developed recommended dietary allowances (RDA) for calcium based on the average daily amount of the nutrient needed to meet the health needs of 97%–98% of the population. The values were raised in 2010 after concerns that the previous recommendations were too low. The revised RDAs for calcium are:

Some good sources of calcium that do not contain lactose are:

A registered dietitian can help people with lactose intolerance develop meal plans that will meet their dietary needs for calcium. Some people may also benefit from taking a calcium supplement. Calcium supplements are available over-the-counter at pharmacies and supermarkets.

Lactose intolerance cannot be cured. The purpose of the lactose intolerance diet is to help people find alternatives to dairy and relieve symptoms of lactose intolerance so that they do not disrupt daily life.

Following a lactose intolerance diet will help control the uncomfortable symptoms of bloating, nausea, stomach cramps, and diarrhea characteristic of lactose intolerance.

Lactose intolerance diets are variable. Individuals must work out through trial and error how much and which lactose-containing foods they can eat without experiencing symptoms. It may take a little while for people to figure out what works best for them.

The greatest risk of lactose intolerance is that an individual will not get enough calcium. With careful planning, however, people with lactose intolerance can obtain enough calcium without consuming dairy products.

The lactose intolerance diet is accepted by medical professionals as a standard treatment for this condition. The diet has existed for many years and is not controversial.

See also Calcium ; Diarrhea diet ; Digestive diseases ; Elimination diets ; Food allergies ; Food sensitivities ; Giardiasis ; Sugar .