Kids digest the darnedest things. While young children can usually digest dairy ’til the cows come home, many adults are lactose intolerant. Research suggests adults lose the ability to digest lactose when they stop eating as much dairy, and gradual reintroduction to dairy can help solve the problem.

I Scream, You Scream — Why It Matters

We all scream… if we’re lactose intolerant. Those with the condition (yeah, lactard sounds catchier, but it isn’t the nicest nickname) don’t have enough lactase enzyme, which is needed to digest lactose, or milk sugarLactose intolerance and lactase deficiency in children. Rings, E.H, Grand, R.J, Büller, H.A. Academic Medical Center, University of Amsterdam, The Netherlands. Current Opinion in Pediatrics, 1994 Oct;6(5):562-7.. Lactose intolerance can develop after infancy or as the result of a disease like gastroenteritis. In rare cases, people are born without the lactase enzyme and are lactose intolerant for life. And lactose intolerant folks can be a real party to sit next to at the pizza place, with symptoms like diarrhea, nausea, stomach cramping, gas, and bloating. Some people can consume more dairy than others before their stomach stages a mutiny. Eight to 12 ounces of milk won’t cause a problem for most kids and teens with primary lactose intolerance.

No wonder we think kids’ stuff is too cheesy. Lactose intolerance is more common among adults, and studies suggest people are more likely to have lactose troubles as they ageDevelopmental changes of lactose malabsorption in normal Chinese children: a study using breath hydrogen test with a physiological dose of lactose. Ting, C.W, Hwang, B., Wu, T.C. Division of Pediatric Gastroenterology, National Yang-Ming Medical College, Taipei, Taiwan. Journal of Pediatric Gastroenterology and Nutrition, 1988 Nov-Dec;7(6):848-51.. Most infants have the enzymes necessary to break down lactose into digestible lactase. (Lucky for them, since this diet isn’t exactly the way to grow up strong.) But research suggests kids start producing less lactase when they’re as young as two years old. Studies have found more than 25 percent of children over age five are lactose intolerantDetermination of lactose intolerance frequency in children with food allergy. Hutyra, T., Iwańczak, B. Akademia Medyczna we Wrocławiu, II Katedra i Klinikia Pediatrii, Gastroenterologii i Zywienia. Pol Merkur Lekarski, 2008 Oct;25(148):340-4.. Some researchers think people have more dairy troubles as they age because their diets include less lactose— but some scientists look to history for an explanation.

Milk the System — The Answer/Debate

Humans weren’t always wired to rely on nutrition from dairy products— lactose tolerance may be a function of evolution. (Thought Darwin grew his Santa beard without dairy?) The lactase gene usually switches off once a baby’s weaned off dairy. But people living in certain regions evolved to keep the gene switched on, since dairy was an important part of their dietAge dependency of the lactase persistence and lactase restriction phenotypes among children in Sri Lanka and Britain. Thomas, S., Walker-Smith, J.A., Senewiratne, B. et al. Department of Clinical Biochemistry, Institute of Child Health/Hospitals for Sick Children, London, UK. Journal of Tropical Pediatrics, 1990 Apr;36(2):80-5.. Scientists suggest some ethnic groups are more likely to be lactose intolerant, possibly because their ancestors had dairy-deficient diets. (No milkshakes in the ancient world, it turns out.) According to People for the Ethical Treatment of Animals (PETA) estimates, 90 percent of Asian Americans and 75 percent of Native Americans and African Americans are lactose intolerant.

For anyone with dairy troubles, it might just take some (milk) to break some! Some scientists believe avoiding lactose products isn’t the only solution. Researchers suggest a diet with small portions of lactose products can help the body adapt and train it to break down lactose. Start with small amounts of milk on a full stomach, natural cheeses, or yogurt. If that doesn’t work, might as well just wear it.

Did you have problems with lactose when you were a kid? How about now? Tell us in the comments below!