How Many People Cannot Digest Milk? Global Statistics & Causes Explained

December 19, 2025 •

4 min read

Approximately 68% of the world's population has lactose malabsorption, a reduced ability to digest milk sugar after infancy, which is the underlying cause of lactose intolerance. However, not everyone with lactose malabsorption experiences the gastrointestinal symptoms associated with lactose intolerance.

Quick Summary

A majority of the global population has some form of lactose malabsorption, with the percentage varying widely by ethnic origin and geography. The condition stems from a lactase enzyme deficiency, which can be managed with dietary adjustments, enzyme supplements, and exploring lactose-free alternatives.

Key Points

Prevalence Varies Widely: Around 68% of the world's population has lactose malabsorption, but prevalence is much higher in populations of East Asian and African descent compared to Northern Europeans.
Not Everyone Has Symptoms: Not all individuals with lactose malabsorption will experience the digestive symptoms of lactose intolerance.
Key Difference from Milk Allergy: Lactose intolerance is a digestive issue caused by a lack of the lactase enzyme, whereas a milk allergy is a potentially severe immune system reaction to milk proteins.
Common Symptoms: Indigestive symptoms like bloating, gas, diarrhea, and cramps are common after consuming lactose.
Management is Possible: Symptoms can often be managed by reducing lactose intake, choosing lower-lactose products like hard cheeses, and using lactase enzyme supplements.
Diagnosis is Simple: A healthcare provider can confirm lactose intolerance using tests like the hydrogen breath test or lactose tolerance test.

Global Prevalence of Lactose Intolerance

Globally, the inability to digest milk is more common than not among adults. While many infants produce enough of the lactase enzyme to break down lactose, this ability often wanes after childhood. The geographic and ethnic variations are significant, reflecting different historical dietary patterns and genetic adaptations to milk consumption.

Regional and Ethnic Differences

East Asian Descent: In many East Asian populations, the prevalence of lactase nonpersistence can be as high as 70 to 100 percent.
African and Hispanic/Latino Populations: High rates are also observed in people of African, Hispanic/Latino, and American Indian descent, often ranging from 60% to over 80%.
Northern European Descent: This population group has the lowest rates of lactose intolerance, with some estimates as low as 5%. This is due to a genetic mutation for lactase persistence that evolved over time in cultures with a history of dairy farming.
Mediterranean and Middle Eastern: Countries in these regions, like Greece and Saudi Arabia, also report high prevalence rates, often exceeding 70%.

Symptoms of Lactose Intolerance

When undigested lactose reaches the large intestine, it is fermented by bacteria, which produces gases and fluids that cause a range of uncomfortable digestive symptoms. These symptoms can appear between 30 minutes and two hours after consuming milk products.

Common symptoms include:

Bloating
Abdominal cramps and pain
Diarrhea
Gas (flatulence)
Nausea and sometimes vomiting

The severity of symptoms depends on the amount of lactose consumed and an individual's level of lactase deficiency.

Understanding the Different Types and Causes

Lactose intolerance is not a single condition but rather a result of lactase deficiency, which can have different underlying causes:

Primary Lactase Deficiency (Lactase Nonpersistence): This is the most common type and is genetically determined. After infancy, lactase production gradually decreases, and symptoms typically emerge during the teenage or adult years.
Secondary Lactase Deficiency: This occurs when the small intestine's lining is damaged by an illness, injury, or surgery, temporarily reducing lactase production. Conditions like gastroenteritis, celiac disease, or Crohn's disease can cause this type.
Congenital Lactase Deficiency: An extremely rare genetic disorder where infants are born with little to no lactase, making it impossible for them to digest breast milk or formula from birth.
Developmental Lactase Deficiency: Seen in premature infants, where the small intestine has not yet developed enough lactase-producing cells. This condition often resolves on its own as the baby matures.

How to Manage a Lactose Intolerant Diet

For most people, complete avoidance of all dairy is not necessary. The amount of lactose one can tolerate varies, and dietary management is often effective.

Reduce Intake: Many individuals can comfortably tolerate small amounts of lactose, like a small amount of milk with a meal.
Choose Lower-Lactose Dairy: Fermented dairy products like hard cheeses (e.g., cheddar, Swiss) and yogurt with live active cultures are often easier to digest because the fermentation process breaks down much of the lactose.
Use Lactase Supplements: Over-the-counter lactase enzyme pills or drops can be taken with dairy products to aid digestion.
Try Alternatives: Lactose-free milk, almond milk, soy milk, and other plant-based beverages are widely available.
Ensure Proper Nutrition: When reducing dairy, it is important to ensure adequate intake of calcium and Vitamin D from fortified foods or supplements to prevent complications like osteoporosis.

Lactose Intolerance vs. Milk Allergy

It is crucial to differentiate between lactose intolerance and a milk allergy, as they involve different bodily systems and have very different risks. The following table compares the key aspects of each condition:


Feature	Lactose Intolerance	Milk Allergy
Bodily System Involved	Digestive system	Immune system
Cause	Lack of the lactase enzyme	Immune reaction to milk proteins (casein or whey)
Symptoms	Bloating, gas, diarrhea, cramps	Hives, wheezing, swelling, vomiting, anaphylaxis
Severity	Uncomfortable but not life-threatening	Can be life-threatening in severe cases
Onset	Usually develops later in childhood or adulthood	Most common in infancy
Diagnosis	Hydrogen breath test, lactose tolerance test, elimination diet	Skin-prick test, blood test for IgE antibodies

Diagnosis: How to Confirm Lactose Intolerance

If you suspect you cannot digest milk, it's best to consult a healthcare professional for a proper diagnosis. Common diagnostic tests include:

Hydrogen Breath Test: After fasting, you drink a lactose-containing liquid. Your breath is then tested for hydrogen gas, which is produced when undigested lactose ferments in the colon. High levels indicate malabsorption.
Lactose Tolerance Test: Your blood glucose levels are measured before and after consuming a lactose-rich drink. A minimal rise in glucose suggests poor lactose digestion.
Elimination Diet: Your doctor may recommend a trial period of avoiding dairy to see if symptoms improve. If they do, reintroducing dairy can help confirm the sensitivity.

Conclusion

The number of people who cannot digest milk is substantial on a global scale, with significant variations influenced by genetics and ancestry. Lactose intolerance, caused by a lactase enzyme deficiency, is a manageable condition that is distinctly different from a potentially serious milk allergy. By understanding the causes, recognizing the symptoms, and exploring dietary strategies and enzyme supplements, individuals can effectively manage their symptoms and maintain a healthy, balanced diet. For a definitive diagnosis and personalized management plan, consulting with a healthcare professional is always the best course of action.

Authoritative Source

National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)

Frequently Asked Questions

Lactose intolerance is a digestive problem caused by the inability to break down the sugar (lactose) in milk due to a lack of the lactase enzyme. A milk allergy is a serious immune system response to the proteins (casein or whey) in milk, which can cause severe, life-threatening symptoms.

Primary lactose intolerance, the most common type, cannot be cured. However, secondary lactose intolerance, caused by another illness or injury, may resolve if the underlying condition is treated. Congenital and developmental types are also typically not reversible.

You should consider reducing or avoiding dairy products like cow's milk, ice cream, cream, and soft cheeses. Many people can tolerate small amounts, while others may need to explore lactose-free alternatives or supplements.

You can get calcium from many non-dairy sources. Good options include leafy green vegetables, fortified orange juice and cereals, canned salmon with bones, and almonds. Your doctor may also recommend a calcium supplement.

Congenital lactose intolerance, where a baby is born with an inability to produce lactase, is extremely rare. However, premature infants may experience developmental lactase deficiency, which usually improves over time.

Yes, many people with lactose intolerance can tolerate fermented products like yogurt with live, active cultures and hard cheeses. The fermentation process breaks down much of the lactose, making it easier to digest.

Lactose intolerance is typically diagnosed with a hydrogen breath test, a lactose tolerance test, or by observing symptom improvement during an elimination diet.