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Milk Allergy vs. Lactose Intolerance or how much lactose can a person with lactose intolerance have?

People sometimes confuse lactose intolerance with a milk allergy, but these are completely different things caused by different components of dairy milk.

Dairy milk is made up of several different components, such as proteins - casein and whey, milk sugar (called lactose), fats and water among many others.

All true food allergies are caused by an immune system overreaction to the proteins. If you have a milk allergy, your immune system identifies certain milk proteins as harmful, triggering the production of antibodies to neutralize those proteins. The next time you come into contact with these proteins, antibodies recognize them and signal your immune system to release histamines and other chemicals, thereby causing a wide range of allergic symptoms from mild (rashes, hives, itching, swelling, etc.) to severe (trouble breathing, wheezing, etc.)

There are two main proteins in cow's milk that can cause an allergic reaction:

1. Casein, which is found in the solid part (curd) of milk that curdles

2. Whey, which is found in the liquid part of milk that remains after milk curdles

People can be allergic to only one type of milk protein or to both. Most people who react to cow's milk will also react to sheep, goat, and buffalo milk. Less commonly, people allergic to cow's milk are also allergic to soy milk.

Lactose, on the other hand, is a sugar found in milk and milk products. The small intestine—the organ where most food digestion and nutrient absorption take place—produces an enzyme called lactase. Lactase breaks down lactose into two simpler forms of sugar: glucose and galactose. The body then absorbs these simpler sugars into the bloodstream.

Lactose intolerance is a condition in which people have digestive symptoms—such as bloating, diarrhoea, and gas—after eating or drinking milk or milk products.

The reasons for lactose intolerance are often Lactase Deficiency and Lactose Malabsorption

With people who have a lactase deficiency, the small intestine produces low levels of lactase and cannot digest much lactose.

Lactase deficiency may cause lactose malabsorption, and undigested lactose passes to the colon. The colon, part of the large intestine, absorbs water from stool and changes it from a liquid to a solid form. In the colon, bacteria break down undigested lactose and create fluid and gas.

People have lactose intolerance when lactase deficiency and lactose malabsorption cause digestive symptoms. Most people with lactose intolerance can eat or drink some amount of lactose without having digestive symptoms. Not all people with lactase deficiency and lactose malabsorption have digestive symptoms and Individuals vary in the amount of lactose they can tolerate.

How much lactose can a person with lactose intolerance have?

Most people with lactose intolerance can tolerate some amount of lactose in their diet and do not need to avoid milk or milk products completely. Avoiding milk and milk products altogether may cause people to take in less calcium and vitamin D than they need to maintain a good and healthy physical condition.

A variety of factors—including how much lactase the small intestine produces—can affect how much lactose an individual can tolerate. For example, one person may have severe symptoms after drinking a small amount of milk, while another person can drink a large amount without issue. Other people can easily eat yogurt and hard cheeses such as cheddar and Swiss, while they are unable to eat or drink other milk products without having digestive issues.

Research suggests that adults and adolescents with lactose malabsorption could consume at least 12 grams of lactose in one sitting without symptoms, or with only minor symptoms at the most. This amount of lactose is equivalent to 1 cup of milk or 200 grams of yogurt. People with lactose malabsorption may be able to consume more lactose if they eat it or drink it with meals or in small amounts throughout the day.

Gradually introducing small amounts of milk or milk products may help some people adapt to them with fewer symptoms. Often, people can better tolerate milk or milk products by having them with meals, such as having milk with cereal or having cheese with crackers. People with lactose intolerance are generally more likely to tolerate hard cheeses, such as cheddar or Swiss, than a glass of milk. A 1.5‑ounce serving of low-fat hard cheese has less than 1 gram of lactose, while a 1-cup serving of low-fat milk has about 11 to 13 grams of lactose.

Did you know that people with lactose intolerance are also more likely to tolerate yogurt and milk kefir than non-fermented milk, even though yogurt and milk have similar amounts of lactose?

People may find it helpful to talk with a registered dietitian about a dietary plan. A dietary plan can help people manage the symptoms of lactose intolerance and make sure they get enough nutrients.


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