Health

Lactose Intolerance

Lactose intolerance is the inability to fully digest lactose, the sugar found in milk and dairy products. It's incredibly common—about 68% of the world's population has some degree of lactose malabsorption.

What's Happening

Your small intestine produces an enzyme called lactase to break down lactose into simpler sugars (glucose and galactose) that can be absorbed into your bloodstream. When you don't produce enough lactase, the undigested lactose moves into your large intestine, where bacteria ferment it—causing gas, bloating, cramps, and other symptoms.

Quick Facts

• Prevalence — 68% of world population has reduced lactase after infancy
• Genetics — Lactase persistence (being able to digest milk as an adult) is actually the mutation
• Geography — Most common in East Asian, West African, Arab, Jewish, Greek, and Italian descent
• Not an Allergy — Lactose intolerance is digestive, not an immune response like a milk allergy

Common Symptoms

• Bloating — That uncomfortable full feeling
• Gas — From bacterial fermentation of undigested lactose
• Stomach Cramps — Often 30 minutes to 2 hours after eating dairy
• Nausea — Sometimes accompanies other symptoms
• Diarrhea — In more severe cases

Managing It

• Lactase Supplements — Lactaid pills taken before eating dairy can help
• Lactose-Free Products — Same taste, lactase already added (Lactaid milk, Fairlife)
• Hard Cheeses — Aged cheeses like cheddar, parmesan, and swiss have very little lactose
• Yogurt — Live cultures help break down lactose, making it easier to digest
• Start Small — Many people can tolerate small amounts of dairy
• Dairy Alternatives — Oat milk, almond milk, coconut milk

Foods to Watch

• High Lactose — Milk, ice cream, soft cheeses, cream, cottage cheese
• Hidden Lactose — Bread, cereals, salad dressings, protein bars, medications
• Usually Safe — Butter (very low lactose), hard aged cheeses, lactose-free products

The Evolution Story

Humans weren't originally able to digest milk as adults. The ability to produce lactase into adulthood (lactase persistence) evolved independently in several populations that domesticated cattle—primarily in Northern Europe, parts of Africa, and the Middle East.

This mutation became advantageous because milk provided a reliable source of nutrition, hydration, and calories. In populations without a history of dairy farming, the gene that keeps lactase production active simply never developed.