Lactose intolerance: symptoms, causes, diagnosis and


Lactose intolerance occurs when your body cannot digest lactose, the sugar found in milk. If you are lactose intolerant, you may experience an upset stomach and digestive problems after consuming dairy products such as milk, ice cream, yogurt, and cheese.

This is not uncommon and it is quite easy to cure. If you are lactose intolerant, you can avoid its effects by limiting your intake of foods that contain lactose. Or you can use over-the-counter enzyme substitutes to help you digest lactose better, but you need to make sure you get the right time.


Lactose intolerance can occur in children and adults, and can begin as early as two years of age. If you were lactose intolerant as a child, it can be a problem throughout your life, or you can overcome it. However, with age, lactose intolerance develops more often.

Common effects of lactose intolerance include :

  • Abdominal cramps
  • Gas
  • Swelling
  • Nausea
  • Diarrhea
  • Abdominal pain

In most cases, these symptoms occur within half an hour to a couple of hours after consuming dairy products .

Eating more foods and drinks that contain lactose often causes more serious symptoms.


If you have severe lactose intolerance, complications can arise. Repeated vomiting or diarrhea can cause dehydration , weight loss, or electrolyte imbalances.

If you have a gastrointestinal (GI) infection, you may experience more noticeable lactose intolerance effects until the infection clears. And if you have a gastrointestinal disorder, such as inflammatory bowel disease or irritable bowel syndrome , it can make lactose intolerance worse .

Nutritional effects

Some people with lactose intolerance avoid all dairy products and may be deficient in important nutrients such as calcium , vitamin D , and protein. This deficiency can cause a number of health consequences, including brittle bones.


Consuming foods and beverages that contain lactose causes allergies. There are many foods and drinks that can cause lactose intolerance.

Common triggers for lactose intolerance include:

  • Milk
  • Ice cream
  • Cheese
  • Yogurt
  • Smoothie
  • White milk sauce
  • Cheese-based foods, such as pizza or pasta and cheese.
  • Creamy dessert filling
  • Custard and pudding
  • Whipping creams
  • Milk-based cream, half and half

Some people experience lactose intolerance from eating certain foods but not others.


Lactose is a sugar found in milk. Your body needs the enzyme lactase (made in the small intestine) to break down lactose into glucose and galactose, sugars that your body can absorb and use. Lactose intolerance occurs when your body lacks the enzyme lactase .

If you can't properly break down lactose, it stays in your digestive system until it's eventually excreted in your stool rather than absorbed. Excess lactose in the digestive system causes fluid to enter the colon, causing symptoms of lactose intolerance, such as diarrhea and stomach cramps.

Lactose intolerance can occur for several reasons:

  • Lactose volatility : The most common cause of lactose intolerance is a decrease in the enzyme lactase with age .
  • Digestive disorders: Conditions like Crohn 's disease or celiac disease can damage lactase-producing cells in the intestine.
  • Hereditary : The least common cause of lactose intolerance is hereditary and can begin at birth. Babies with this condition may not be able to digest breast milk and may need lactose-free formula.

Even with low levels of lactose, natural bacteria called lactic acid bacteria can break down lactase. In some people, the effect of this bacteria is reduced.

Please note that lactose intolerance is not a milk allergy . Allergies are very different and their effects are mediated by an inflammatory response.


If you have symptoms of lactose intolerance, it is best to speak with your healthcare professional for a formal diagnosis and advice specifically tailored to your health and medical needs.

Many people self-diagnose lactose intolerance in themselves or their children. Be aware that you may encounter another medical problem that causes symptoms similar to lactose intolerance, such as infection, inflammatory bowel disease, malabsorption, or food allergies.

Elimination diet

An elimination diet can be helpful in diagnosing lactose intolerance. When using this type of diet, you must eliminate all dairy products to see if the symptoms go away. When using an elimination diet, it is important to exclude only one food category (eg dairy) so that the result is not confusing.

Diagnostic tests

Lactose intolerance can be diagnosed by several tests. These include a lactose tolerance test, a breath test, or a stool test .

  • Lactose tolerance test: A blood test, called a lactose tolerance test, can measure fasting glucose levels. Then you will be given a drink that contains lactose. If you cannot properly break down and metabolize lactose, your blood glucose levels will not rise as expected after consuming the drink.
  • Hydrogen breath test: This test measures the hydrogen in your breath after you have drunk a beverage that contains lactose. A high hydrogen content in your breath means that it cannot break down lactose.
  • Stool Sample – The stool test measures undigested lactose in stool and is often used for infants and young children.

Watch out

Treatment for lactose intolerance is to avoid foods that contain lactose or to replenish the enzyme lactase in the body.

You may find that you can tolerate cheese but not ice cream, or yogurt but not milk. It's perfectly fine to eat foods and drinks that don't cause you any problems, while avoiding foods that cause you physical discomfort.

Diet changes

Most dairy products contain lactose, but not all dairy products are high in lactose. For example , hard cheeses are made with only milk protein and contain little or no lactose sugar.

Fermented dairy products contain less lactose and you can tolerate them better. This is because they are produced by allowing bacteria to convert some or all of the lactose into lactic acid. Fermented dairy products include yogurt, kefir, sour cream, buttermilk, and cream.

Lactose-free milk and lactose-free ice cream are available at most grocery stores. Most people with lactose intolerance do not experience symptoms when consuming these lactose-free dairy products.

Lactase supplements

There are ways to consume foods and beverages that contain lactose, even if you are lactose intolerant.

Over-the-counter lactase enzyme supplements can be taken before consuming dairy products. Be sure to follow the directions on the package when taking them to reap the benefits at the right time.

Probiotics , beneficial bacteria that live naturally in the digestive tract , can help relieve symptoms in some people with lactose intolerance. If your healthcare provider offers you probiotics, you can take them in yogurt or capsule form, which can usually be found in the refrigerated sections of health food stores.

Get the word of drug information

Lactose intolerance affects 70% of the world's population. In general, this condition causes physical discomfort, but it is rarely dangerous to your health. If you really need to skip dairy entirely, be sure to replace the nutrients in milk with other foods that contain protein, calcium, and vitamin D.

Frequently asked questions

  • Globally, about 65% of adults are lactose intolerant. Children under 5 years old suffer from this disease infrequently.

  • Your small intestine cannot digest a sugar called lactose due to a lack of an enzyme called lactase. This lactose travels through the digestive tract to the colon, where bacteria feed on it. This produces gas that causes flatulence and bloating, diarrhea , and other symptoms.

  • Yes. Some people, especially those of African, Asian, or Latino descent, produce less lactase as they age, so they may develop lactose intolerance later in life. Similarly, anyone with a medical condition that damages the lining of the small intestine , such as celiac disease, tropical sprue, or an acute infection, can become lactose intolerant.

  • The richest non-dairy sources of calcium include:

    • Calcium-fortified foods and beverages such as orange juice, soy milk, cereals, and breads.
    • Canned fish with bones such as sardines and salmon.
    • Green leafy vegetables like broccoli, kale, mustard greens, kale, and bok choy.
    • Almonds and Brazil nuts
    • Sunflower seeds
    • Tahini
    • Molasses
    • Dried figs

  • If you are unable to eat any amount of dairy and cannot meet the RDA for calcium with alternative sources of calcium, supplementation is probably recommended. Talk to your healthcare provider or dietitian about which calcium supplement is best for you (calcium citrate or calcium carbonate) and how much to take based on your regular diet. A typical recommendation is 1,200 to 1,500 milligrams per day.

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