Lactose Intolerance – Symptoms and Causes
What Happens When You Can’t Digest Milk Sugar
The human digestive system relies on specific organs to process different foods properly. When someone has lactose intolerance, their body lacks enough lactase enzyme to break down milk sugar.
This shortage typically occurs in the small intestine. The small intestine and colon work together as key parts of your digestive tract.
When food passes through your system, the small intestine absorbs nutrients from what you eat. Any undigested material moves into the colon and eventually passes as stool during bowel movements.
For people with lactose intolerance, undigested lactose enters the colon, where bacteria ferment it, causing uncomfortable symptoms like gas, bloating, and diarrhea. This reaction happens because the body couldn’t properly break down the milk sugar earlier in the digestive process.
Despite these challenges, most people with lactose intolerance don’t need to completely eliminate dairy from their diet. Many can enjoy small amounts of dairy products or use lactase supplements to help their bodies process lactose more effectively.
Symptoms
Symptoms of lactose intolerance typically appear 30 minutes to two hours after consuming lactose-containing foods or drinks. Common symptoms include:
- Diarrhea
- Nausea (sometimes with vomiting)
- Stomach cramps
- Bloating
- Gas
These symptoms occur because the body cannot properly digest lactose, the sugar found in milk products.
When to See a Doctor
If you often feel unwell after consuming dairy products, it’s time to talk to a healthcare provider. This is especially important if you’re concerned about getting enough calcium in your diet.
Your doctor can help determine if your symptoms are due to lactose intolerance and suggest appropriate treatments or dietary changes.
Why Lactose Intolerance Happens
Lactose intolerance happens when the body doesn’t make enough lactase enzyme to break down lactose (milk sugar). Most people with this condition have primary lactose intolerance.
These individuals start life with plenty of lactase, which helps babies digest milk. As they grow and add other foods to their diet, their lactase levels naturally decrease. By adulthood, the amount drops significantly, making dairy products hard to digest.
Some people develop lactose intolerance after an illness or injury affects their small intestine. This is called secondary lactose intolerance. Several health problems can cause this type:
- Intestinal infections
- Celiac disease
- Bacterial overgrowth in the gut
- Crohn’s disease
When doctors treat the main health problem, lactase levels might return to normal. However, this recovery can take time.
Lactose Intolerance from Birth
Some babies are born without the ability to make enough lactase. This rare condition is called congenital lactose intolerance. It passes from parents to children through genes.
For a baby to have this condition, both parents must pass on the same gene variant. Premature babies may also have temporary lactose intolerance because their bodies haven’t yet developed enough lactase.
When lactase is missing, undigested lactose moves to the colon instead of being absorbed by the body. In the colon, bacteria interact with this undigested lactose, causing uncomfortable symptoms.
Risk Factors
Several factors can increase the chance of developing lactose intolerance:
Age
- Lactose intolerance rarely affects babies and young children
- It more commonly develops during adulthood
Ethnic Background
People with these backgrounds have higher rates of lactose intolerance:
- African
- Asian
- Hispanic
- American Indian
Birth Circumstances
- Premature babies may have lower lactase levels
- Lactase-producing cells typically develop late in the third trimester
Intestinal Conditions
Certain digestive issues can lead to lactose intolerance:
- Bacterial overgrowth in the small intestine
- Celiac disease
- Crohn’s disease
Cancer Treatment Effects
- Radiation therapy to the stomach region
- Intestinal complications from chemotherapy
