Here are the main causes of lactose intolerance:
1. Primary Lactase Deficiency (Most Common Cause)
This is the most common reason people develop lactose intolerance. As children grow older, the body naturally produces less lactase. For many adults worldwide, this decline is completely normal.
This type usually develops gradually and becomes noticeable in teenage or adult years.
2. Secondary Lactose Intolerance
Secondary lactose intolerance happens when illness, infection, or injury damages the small intestine.
Common triggers include:
- Gastroenteritis (stomach flu)
- Celiac disease
- Crohn’s disease
- Intestinal surgery
The good news? This type can sometimes be temporary if the gut heals properly.
3. Congenital Lactase Deficiency (Rare)
This is a rare genetic condition where babies are born without the ability to produce lactase at all. It requires immediate medical management and a lactose-free diet from infancy.
4. Developmental Lactose Intolerance
Premature babies may temporarily have low lactase levels because the enzyme develops later in pregnancy. This usually improves as the baby grows.
