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Does Lactose Intolerance Relate to Acne?

There Is No Scientific Concensus and Too Little Evidence Thus Far, But It Is An Interesting Thing to Consider

The Essential Information

People with lactose intolerance are unable to fully digest the sugar (lactose) in dairy products, the consumption of which leads to:

  • Gas
  • Bloating
  • Diarrhea

Lactose intolerance is genetic, so if your parents are lactose intolerant, your chances of also being lactose intolerant increase. Genetic changes ultimately cause a deficiency of lactase in the small intestine, which is an enzyme that the body produces that digests the lactose in dairy foods.

What about acne? Does ingesting dairy lead to acne when you are lactose intolerant, or lactose tolerant for that matter?

If you're lactose intolerant - we don't know: There is no scientific consensus on whether eating dairy foods while lactose intolerant would impact acne, and if so, to what degree.

If you're lactose tolerant - we have an initial area of interest: If we look only at the things we do know, the only tangential connection we could draw would be when people who are lactose tolerant ingest dairy products, their body effectively turns the lactose in the dairy products into sugar. This increases blood sugar levels, which in turn, increases insulin. More insulin can lead to other hormones temporarily increasing. Since acne is a hormonal disease, anything that increases hormone levels should draw scrutiny. However, this is something of a stretch. Ingesting any type of carbohydrate would cause this type of blood sugar spike, not just dairy.

The Science

The Body Needs Lactase to Properly Digest Dairy

Almost all infants are able to digest milk and specifically lactose, the sugar in milk and other dairy products. To digest dairy, the body needs a specific enzyme in the small intestines called lactase. Lactase breaks down lactose into glucose and galactose, which then pass through the wall of the bowel into the bloodstream, where the body uses them for energy.

Lactose Digestion Vs. Lactose Intolerance

After infancy, most people gradually produce less lactase, leading to the reduced ability to digest lactose. Therefore, most people in the world - about 65%1 - eventually develop lactase non-persistence, meaning the body does not persist in producing enough lactase to digest dairy.

People who are able to digest dairy into adulthood can do so because their bodies continue to produce lactase, and they are said to have lactase persistence.

Who Maintains Lactase Persistence, and Who Does Not?

Lactase persistence is more common in populations that have been consuming dairy for many centuries. For example, northern Europeans are thought to have introduced dairy into the diet about ten thousand years ago, leading to a genetic mutation (a permanent, inheritable alteration in a gene) that underlies lactase persistence. Today, people in northern European countries still consume dairy products throughout their lives, just like their ancestors did. In contrast, in many parts of Asia, and a place where historically people did not use animal milk for food, the overwhelming majority of people have lactose non-persistance.

This table shows the percentage of people with lactase non-persistence by ethnic group:3

Lactase Non-persistance in Various Ethnic Groups

Does Everyone with Lactase Non-persistence Experience Lactose Intolerance?

Lactose intolerance is essentially the same as lactase non-persistence. The only difference is that some lactase non-persistent people do not experience symptoms, but all lactose-intolerant people do. Lactase non-persistence does not always lead to lactose intolerance. Most of the world's population is lactase-non-persistent, but not all experience the symptoms of lactose intolerance since other factors also affect tolerance, such as:4

  • The quantity of dairy consumed and how much is consumed at one time
  • The amount of lactose in the dairy product

According to the National Institute of Health, "Most people with lactase non-persistence retain some lactase activity and can include varying amounts of lactose in their diets without experiencing symptoms. Often, affected individuals have difficulty digesting fresh milk but can eat certain dairy products such as cheese or yogurt without discomfort. These foods are made using fermentation processes that break down much of the lactose in milk."2

A Closer Look at Lactose Intolerance in the Body

When the lactase enzyme is absent, lactose cannot be broken down and therefore remains in the bowel. From the small intestine, lactose is then transported into the large intestine, where bacteria change it into a form of sugar that cannot pass through the intestinal wall called monosaccharides. These monosaccharides stay in the bowel and attract more water, turning normal stool into diarrhea. Also, the process of changing lactose into monosaccharides produces gasses that cause distension (bloating), abdominal pain, borborygmi (noise-causing gas), and diarrhea.3 The following diagram shows what happens when the body no longer produces adequate lactase and the person experiences lactose intolerance.

Lactose Intolerance

Lactose Intolerance Symptoms

The symptoms of lactose intolerance typically occur between 30 minutes and 2 hours after eating or drinking dairy. The most common symptoms are:

  • Abdominal pain
  • Bloating of the belly caused by the presence of gas in the intestines, which can lead to diarrhea

People may also experience:

  • Constipation
  • Nausea and vomiting
  • Headache
  • Lightheadedness
  • Muscle pain3

Symptoms of Lactose Intolerance

Diagnosing Lactose Intolerance Reveals a Possible Link to Acne

One of the diagnostic tests for lactose intolerance measures the level of glucose in the bloodstream after taking in lactose. This test involves taking a 50-gram oral dosage of lactose in water. Afterward, several blood samples are drawn to see the level of glucose in the bloodstream. The test is positive for lactose intolerance when the patient develops symptoms and the blood glucose level does not increase significantly. In a person who is lactase persistent, blood tests show a peak in the blood glucose level in the bloodstream after consuming 50 grams of lactose.3 This occurs because lactase breaks down lactose into glucose and galactose. In a person who is lactose intolerant and/or lactase-non-persistent, blood tests would not indicate this spike in blood glucose because there is not enough lactase to break down lactose and convert it into glucose. In short, lactase persistence means that consuming dairy products increases the level of glucose in the bloodstream.

Lactose Intolerance and Blood Sugar Level

Some evidence shows that eating sugary, high-glycemic foods may contribute to acne, which raises the question of whether people who are lactose tolerant and consume dairy experience more acne symptoms. This is for debate, and we currently do not have enough evidence to know.

Lactose Tolerant or Intolerant: What Does This Entail for Me?

Not everybody with lactase non-persistence experiences lactose intolerance. If you are lactase-non-persistent and only consume a small amount of lactose-containing foods throughout the day, you may not experience any symptoms. As you can see from the table below, some dairy products have more or less lactose than others.4

Lactose Content on Dairy Products

People who are lactose intolerant should avoid foods containing lactose to reduce or eliminate symptoms. The table below shows which foods to avoid if you need to exclude lactose from your diet.4

Food Ingredients to Avoid on a Lactose Exclusion Diet

There currently is no treatment for lactose intolerance, but there are over-the-counter tablets that contain the lactase enzyme. These tablets should be taken at the beginning of a meal so that the lactase enzyme in the tablets can provide enough lactase in the bowel. Studies show that these tablets are effective in reducing the symptoms of lactose intolerance.3

If you experience no problems when consuming dairy products, yet suffer from acne, you may want to try reducing the consumption of such products to see whether that results in fewer breakouts. We know that digesting lactose causes a rise in blood sugar, and this may affect acne. Even if it does to some degree, eliminating dairy is unlikely to clear the skin, but it could be something interesting to try. For more information, see this article on diet and acne.


The lactase enzyme is necessary to digest lactose, a sugar present in dairy products. In up to 70% of the world's population, the body gradually stops producing lactase as people age. This means most people become increasingly less able to digest lactose, which is called lactase non-persistence. Those who are lactase-non-persistent and have symptoms after consuming dairy are lactose intolerant. There is no treatment for lactose intolerance. Adjusting the intake of lactose may reduce symptoms, and taking lactase replacement tablets at the beginning of a meal has been shown to be effective in reducing symptoms. People who tolerate lactose typically have spikes in blood glucose levels after consuming dairy because the amount of glucose in the bloodstream raises when lactose breaks down into glucose and galactose. Some evidence suggests that eating high-glycemic foods may contribute to acne, so reducing consumption of dairy products may lead to a reduction in acne symptoms.

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  1. Ingram, C. J. et al. Lactose digestion and the evolutionary genetics of lactase persistence. Hum Genet 124, 579 - 591 (2009).
  2. lactose intolerance, <https://ghr.nlm.nih.gov/condition/lactose-intolerance#expand-collapse-start>.
  3. Harrington, L. K. & Mayberry, J. F. A re-appraisal of lactose intolerance. Int J Clin Pract 62, 1541 - 1546 (2008).
  4. Lomer, M. C., Parkes, G. C. & Sanderson, J. D. Review article: lactose intolerance in clinical practice- myths and realities. Aliment Pharmacol Ther 27, 93 - 103 (2008).

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