What causes Lactose Intolerance?


Lactose intolerance occurs when the small intestine does not produce enough of an enzyme called lactase. Your body needs lactase to break down, or digest, lactose (the sugar found in dairy products).

Lactose intolerance generally develops in individuals as they age. People tend to become lactose intolerant around their teenage years, or during adulthood (ages 30 to 40). Generally, lactose intolerance most commonly runs in families and is related to one’s family’s genes. Lactose intolerance can also be brought on by infections, chemotherapy, penicillin reactions, surgery, pregnancy, or from the avoidance of dairy products for a prolonged period of time. Additionally, specific ethnicities are more likely to suffer from lactose intolerance than others.

On rare occasions, newborns are lactose-intolerant. Usually newborns outgrow the condition as they get older.


One’s genes can play a key role in being able to consume dairy product without symptoms. One’s genetic make-up dictates if his or her body can produce enough lactase enzyme, an enzyme the body needs to break down dairy products. Many ethnic cultures are in fact more likely to be lactose intolerant because their diets call for low lactose intake. Over generations, these ethnic groups don’t pass on the enzyme to break down dairy because they aren’t consuming dairy.

Lactose Intolerance by Ethnic Groups:

African Blacks 95%
American Indians 90%
Asian Americans 90%
North American Blacks 75%
Mexican Americans 75%
Mediterraneans 60%
North American Whites 15%

Medications & surgery incidence of lactase deficiency

Disclaimer: No medical doctor has reviewed the contents of this website/ blog. This website/blog was development for the purpose of providing a central place for lactose intolerant individuals to come to share basic information and personal insight. It is advised that you check with your physician or medical advisor before acting upon anything learned from this site.