Why Are So Many People Lactose Intolerant?

Humans are the only mammals who eat dairy into adulthood.

Dr. Linda Dahl
5 min readSep 10, 2022
Photo by Mae Mu on Unsplash

When I was a junior in college, I thought I’d developed an ulcer. I would get gnawing gut pains, sometimes accompanied by burping or bloating. I looked up the symptoms in a textbook (there was no internet in those days), and all signs pointed to acid reflux. It made sense, what with all the stress I was dealing with in my pre-med classes and work-study. I could almost feel the acid burning a hole through my stomach.

The remedy, I had read, was to eat a lot of dairy. It was thought to “neutralize” acid. That sounded great to me. My favorite meal was ice cream. On really bad nights, I would scarf down an oversized chocolate peanut butter cone in place of dinner and try to convince myself I felt better. To my surprise, my symptoms got worse. I even started getting diarrhea. And the gas–so noxious it would have knocked out Arnold Schwarzenegger. (Terminator 2 was super popular back then.)

One day, I asked the medical student in my research lab what she thought.

“Lactose intolerance,” she diagnosed, confidently.

“What’s the treatment?” I asked.

In the days before Lactaid, her answer was funereal. “Stop eating dairy.”

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Dr. Linda Dahl
Dr. Linda Dahl

Written by Dr. Linda Dahl

Physician. Author of Tooth and Nail:The Making of a Female Fight Doctor & Better Breastfeeding, http://www.drlindadahl.com @doctorlindadahl

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