Lactose Intolerance Fact Sheet

What is lactose and lactose intolerance?

Lactose is the sugar found in the milk of animal. Lactose intolerance is the inability to digest the lactose in milk and milk products. Lactase deficiency is the most common food intolerance in the world. 

 What are the symptoms of lactose intolerance?

Symptoms differ from patient to patient. The most common symptoms are gas, diarrhea, abdominal distension, cramping, and generalized abdominal pain. 

 How is lactose intolerance diagnosed?

The two common methods of diagnosing lactose intolerance are the lactose tolerance test and the hydrogen breath test.

In the lactose tolerance test, you drink a large amount of a sweet drink containing lactose. If the lactose is not completely absorbed, your blood glucose level will not rise as it would in people with normal lactose tolerance. A low increase in blood glucose is indicative of lactose intolerance.

In the hydrogen breath test, you exhale into a machine, and the hydrogen level is measured. Then you drink a beverage full of lactose and exhale into the machine again. Your hydrogen level is measured because hydrogen is produced in the intestines if the lactose that you consume isn’t digested.

Lactose intolerance often doesn’t become a problem until late childhood or early adulthood. Stool acidity tests are used to diagnose lactose intolerance in infants and young children. Undigested lactose creates lactic acid and other fatty acids, which are detectable from a stool sample. 

What dietary changes should I make if I am lactose intolerant? 

Some people with lactose intolerance can consume some milk, up to ½ Cup (C) at a time and up to 2 C/day. However, it is likely that you will need to exclude all milk products from your diet initially. Look for lactose on the labels of all processed foods. Check labels when purchasing vitamins and medications, because many contain lactose. Lactose is hidden in many foods that you would not necessarily think of, such as luncheon meats; so, it is very important that you study ingredient lists. Look for the words “whey” and “curds” on all food products, and avoid foods that contain them. MSG (monosodium glutamate) often contains lactose. Avoid these foods, at least initially:

▪ Cheese

▪ All milk, including powdered milk, evaporated milk, buttermilk 

▪ Yogurt

▪ Sour cream

▪ Coffee creamer

▪ Whipped cream

▪ Milk powder or solids

▪ Ice cream

▪ Sherbet

▪ Pudding

▪ Butter

▪ Margarine

▪ Chocolate

▪ Cream sauces

▪ Any cream fillings

▪ Many food mixes, such as cake mixes

▪ Many snack foods, such as crackers

▪ Many ready-to-eat breakfast cereals

▪ Many powdered drink mixes

▪ Many instant soups

▪ Many potato mixes

▪ Many salad dressings

▪ Many lunch meats


What foods can I eat?

Fresh meat, poultry, seafood, fruits, and vegetables always are safe, although milk is sometimes added during preparation. Sometimes you may need to call or write to certain food companies to find out if their products contain lactose, because manufacturers are not required by law to put this information on the label. You will need to use caution when eating out or when eating food prepared by others. Ask for information about how the food was prepared.

What about lactose-reduced foods or those over-the-counter drugs?

Lactose-reduced foods are treated with an enzyme called lactase. This enzyme is also what is in the over-the-counter drugs that you may have heard of. The tablets or liquid are either added to milk or milk products before consuming the food, or are taken orally before eating. The lactose content of food can be reduced by about 70% by using these enzymes. Ask your doctor or dietitian if these foods or supplements are appropriate for you.  

I know someone who is lactose intolerant, but still eats yogurt. Why?

Different people have different levels of lactose intolerance. Some people have a less severe reaction to lactose and find that they can eat fermented-milk products without having any symptoms. These fermented-milk products include yogurt and aged cheeses, such as cheddar.  Talk to your doctor or a registered dietitian before trying these food products yourself. 

What are probiotics and will they help me?

Probiotics are living organisms that are present in all people’s intestines. They help our digestive systems. Probiotics are available in pill form and are sometimes recommended for people with various gastrointestinal problems. Some research has shown that they also may aid lactose digestion. Probiotics generally are considered safe if taken in appropriate dosages. You may want to speak to your doctor or dietitian about trying them. 

What about calcium?

It is possible to get enough calcium in your diet without milk products, although it will be more difficult. For absorption, calcium relies on other vitamins and minerals; so, it’s important to eat a diet that is nutritious overall. You should consider supplements if you can’t get enough calcium from whole foods. Look for supplements that consist of calcium carbonate. Sources of calcium for people on a milk-free diet include:

Collard greens, turnip greens, and mustard greens

Canned mackerel, salmon, shrimp, or tuna

Sardines in oil


Fortified oatmeal

Canned oysters


Brussels sprouts


Bok choy



Fortified soy milk

Pinto beans



Download the Lactose Intolerance Fact Sheet