Lactose Intolerance vs. A1 protein intolerance

Lactose Intolerance vs. A1 protein intolerance

Many people, even trained healthcare professionals, assume if they have discomfort after drinking milk that they are lactose intolerant without being tested to get a confirmed diagnosis. Nonetheless, restricting or eliminating milk from the diet results in relief from symptoms. However, survey data shows that dietary patterns low-in or free-from milk and dairy foods make it difficult for people to meet their daily recommendations of key nutrients like vitamin D, calcium and potassium. Moreover, some clients can’t or won’t give up milk and other dairy foods, even if they cause digestive distress.
Before asking clients to restrict or eliminate dairy, consider the following about Lactose Intolerance:

The Basics

Lactose Intolerance is a condition in which people have digestive symptoms like gas, bloating and diarrhea after eating or drinking foods that contain lactose (a sugar naturally found in milk and milk products). The digestive symptoms are caused by lactose malabsorption which happens when the small intestine can’t digest all the lactose in food or drinks, so the component nutrients are not absorbed into the bloodstream.
Research has shown that not everyone with lactose malabsorption has digestive symptoms after they consume lactose; these people are not considered Lactose Intolerant, instead they are “lactose malabsorbers”. Only when a person has lactose malabsorption AND shows GI symptoms are they diagnosed with Lactose Intolerance. Studies have shown that most people with lactose intolerance can consume some amount of lactose without having symptoms (Savaiano, 2006).

Lactose Malabsorption

While most infants can digest lactose, many people begin to develop lactose malabsorption after their first birthday. Survey data estimates that about 68% of the world’s population has lactose malabsorption. However, that does NOT mean all those people have lactose intolerance. In fact, while lactose malabsorption causes lactose intolerance, not all people with lactose malabsorption have lactose intolerance. In the United States, it is estimated that about 36% of people have lactose malabsorption. (Storhaug, 2017)

What Causes Lactose Malabsorption?

The symptoms of Lactose Intolerance are caused by lactose malabsorption. In lactose malabsorption, the small intestine makes low levels of lactase (the enzyme that breaks down lactose) which means that the lactose from food and drink is not digested completely.

Undigested lactose passes into the colon where friendly bacteria break it down into water and gas. In some people, this water and gas causes lactose intolerance symptoms like bloating, gas and diarrhea.

Anything that reduces the amount of lactase produced in the small intestine can cause lactose malabsorption which may result in lactose intolerance symptoms.

Causes of Lactose Intolerance

• Injury to the small intestine: Infections, diseases and other inflammatory conditions may reduce the ability of the intestine to produce lactase. Treatments like medications, surgery or radiation therapy may also injure the small intestine. Lactose intolerance caused by injury to the small intestine is called secondary lactose intolerance. If the cause of the injury is treated, people may be able to tolerate lactose again.
• Genetics: Some people carry a gene that helps them produce lactase, thus digest lactose. People who do not have this genetic predisposition have “lactase nonpersistance”, which means that their bodies’ ability to make lactase decreases with age. In this case, symptoms of lactose intolerance may not begin until later childhood, the teen years or early adulthood. Lactase nonpersistence, also called primary lactase deficiency, is the most common cause of low lactase levels.
• Premature birth: In premature babies, the small intestine may not make enough lactase for a short time after birth. Babies usually recover the ability to produce lactase in time.
• Congenital lactase deficiency: Is a rare genetic condition in which the small intestine makes little or no lactase, starting at birth.

Milk Allergies are NOT due to Lactose

Milk allergies are caused by the immune system’s response to one or more proteins in milk and milk products. Milk allergies usually appear within the first year of life, while lactose intolerance typically appears later. Allergic reactions to milk proteins can be life threatening.

Diagnosing Lactose Intolerance

Diagnosing lactose intolerance can be tricky. In most cases, it is self-diagnosed by eliminating milk and dairy foods, then watching for GI symptoms. If uncomfortable GI symptoms disappear, people usually blame it on lactose.

When a healthcare professional is involved, lactose intolerance should be diagnosed by assessing symptoms and triggers and by ruling out the presence of other health problems like IBS, celiac disease, Crohn’s, Ulcerative Colitis or SIBO (small intestine bacterial overgrowth). In addition, a physician can order a hydrogen breath test to determine if lactose is being malabsorbed.

Hydrogen Breath Test

To diagnose lactose malabsorption, doctors can use the Hydrogen Breath Test (although it is not often covered by insurance). It’s based on the fact that if lactose is not absorbed normally, there is a higher amount of hydrogen exhaled than normal.

For this test, patients drink a liquid with a known amount of lactose. Every 30 minutes, the patient breaths into a balloon-type container that measures the amount of hydrogen in the breath. During this time, the doctor or other healthcare professional should be asking questions about symptoms. If both breath hydrogen levels are elevated AND symptoms are present and get worse throughout the test, then the diagnosis is Lactose Intolerance.


Bayless TM, Brown E, Paige DM. Lactase non-persistence and lactose intolerance. Current Gastroenterology Reports. 2017;19(5):23.
Luyt D, Ball H, Makwana N, et al; Standards of Care Committee (SOCC) of the British Society for Allergy and Clinical Immunology (BSACI). BSACI guideline for the diagnosis and management of cow’s milk allergy. Clinical and Experimental Allergy. 2014;44(5):642–672.
Misselwitz B, Fox M. What is normal and abnormal in lactose digestion? The Lancet. Gastroenterology & Hepatology. 2017;2(10):696–697.
Savaiano, et al., Lactose intolerance symptoms assessed by meta-analysis: a grain of truth that leads to exaggeration. J Nutr. 2006;136(4):1107-13.
Storhaug CL, Fosse SK, Fadnes LT. Country, regional, and global estimates for lactose malabsorption in adults: a systematic review and meta-analysis. The Lancet. Gastroenterology & Hepatology. 2017;2(10):738–746.

A1 protein intolerance
You likely have clients who experience digestive issues after drinking milk. In fact, millions of Americans say they experience post-dairy digestive discomfort. And while they may think their symptoms are a result of undigested lactose, a growing body of evidence points to another culprit—the A1 beta casein protein. However, there’s no diagnostic test for A1 protein intolerance, so how do you know if it is affecting your clients?

To determine if a patient is reacting to lactose or to A1 protein, the following protocol may be useful:

1. Eliminate all milk and milk products for 2 weeks.
2. Introduce an A1 protein free milk (either commercially available A1 protein free cows milk like a2 Milk® or goat or sheeps’ milk) in small amounts with other foods (like 2T in a cup of coffee or tea or on top of granola). Observe symptoms.

• If symptoms are not present, the amount of A1 protein free milk can be increased gradually. Most people can drink up to 1 cup of A1 protein free milk without experiencing post-dairy digestive discomfort symptoms. At this point, it can be assumed that the person is intolerant to the A1 protein and not to lactose.

• If symptoms are present, it can be assumed that the intolerance is caused by lactose and lactose-free milk should be tried next.

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