Lactose intolerance is a digestive disorder caused by the inability to digest lactose. Those with lactose intolerance don’t make enough of the enzyme lactase, which is needed to digest lactose. Lactose is the main carbohydrate in dairy products.
The disorder is relatively very common, affecting millions of people in the U.S. alone.
Lactose intolerance can start at birth or can develop suddenly later in life, even if the individual has never had a problem with dairy before. Lactose intolerance in infants is caused by a mutation of the LCT gene, resulting in life-long intolerance. In adults, the disorder is caused by decreasing activity of the LCT gene, resulting in an increasing inability to digest lactose as an individual ages. About 65% of the adult human population has this type of lactose intolerance.
Lactose intolerance is generally harmless but its symptoms can cause extreme discomfort. Symptoms of lactose intolerance appear after consuming lactose or dairy and include:
- Abdominal cramps
Lactose malabsorption causes the digestive symptoms of lactose intolerance. Not everyone with lactose malabsorption has digestive symptoms after consuming lactose. Only those who have symptoms have lactose intolerance.
Treatment for the disorder includes avoiding dairy, the use of lactase supplements (such as Lactaid), and the use of lactose-free products. While treatment can help prevent symptoms, there is no cure for this condition.
Those who have lactose intolerance and need to avoid consuming dairy products run the risk of not receiving enough nutrients, specifically calcium and vitamin D. A lack of calcium can lead to osteoporosis, a condition in which one’s bones become brittle and more likely to break. The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) has guidelines on how to eat with lactose intolerance without sacrificing your nutritional needs.
Lactose Intolerance Around the World
In the United States, individuals who are from or whose families are from parts of the world where lactose malabsorption is more common are more likely to have lactose intolerance. According to the NIDDK, those who are American American, American Indian, Asian American, or Hispanic/Latino are more likely to have lactose malabsorption.
The ten countries with the highest prevalence of lactose intolerance are:
- Ghana - 100%
- Malawi - 100%
- South Korea - 100%
- Yemen - 100%
- Solomon Islands - 99%
- Armenia - 98%
- Vietnam - 98%
- Zambia - 98%
- Azerbaijan - 96%
- Oman - 96%
Lactose intolerance is generally most common in Asian countries, especially in East Asian, where about 70-100% of people show lactose intolerance.
The ten countries with the lowest prevalence of lactose intolerance are:
- Denmark - 4%
- Ireland - 4%
- Sweden - 7%
- United Kingdom - 8%
- New Zealand - 10%
- Netherlands - 12%
- Norway - 12%
- Niger - 13%
- Belgium - 15%
- Cyprus - 16%
Lactose intolerance is least prevent in Northern and Central Europe, where only about 5% of the population has lactose intolerance.