DRHOOK- Cowed: Lactase lack means GI trouble

the handsome doctor John Hong of Charlottesville

"Got Milk?" is probably one of the best ads ever. The milk mustache, though, is kind of weird to see on supermodels and athletes. But then again, as I get older I see that I'm starting to spill food and miss my mouth more often when I eat and drink. (Why does this happen to us as we age?)

 I grew up drinking milk. We even had a milkman come to the door twice a week. It was my chore to take the milk out of the milk box on the front porch. Sounds simple enough, but I seemed to forget quite often. At suppertime, my mom would ask me, "Did you get the milk?" Oops!

So I'd go to the porch to collect frozen milk (winter time) or sour milk (summer time). Needless to say, we had good milk only in the spring and fall. But you know what? Milk was really like Milk of Magnesia for me because it gave me diarrhea.

 Should lactose intolerance be considered the norm instead of a disease?

 USA Today on August 31 printed that 60 percent of people are lactose intolerant. So really shouldn't we spin it that 40 percent of the world is lactose persistent? 

 First of all, what is lactose? It's milk sugar. The small intestines have cells that produce an enzyme, lactase, to digest the lactose into two smaller sugars: glucose and galactose. (I bet Carl Sagan's favorite sugar was Galactose.)

 However, if the small intestines stop producing lactase, up to 75 percent of the lactose will zoom to the colon where bacteria will then be like fraternity brothers who just bought a keg of beer: they'll gobble up all the lactose to produce hydrogen gas and short-chain fatty acids. The literally "end" results: gas, flatulence, bloating, diarrhea, and even nausea and vomiting (the last symptoms particularly prevalent in adolescents). 

 Almost every infant and very young child has small intestinal production of the enzyme lactase. But by the ages two to five, it goes away for most people– like in 100 percent of Native Americans, 95 percent of Asians, 75 percent of Africans Americans and Caribbeans, and 50 percent of Hispanics.

 On the other hand, only 10 percent of northern Europeans lack lactase. PLoS Computational Biology published a study that showed that about 7,500 years ago there was a genetic adaptation to help some ethnicities continue their lactase production past the age of five. Perhaps this genetic change was in response to the lack of sunlight in northern Europe, where they don't get enough vitamin D. And what foods do you think of when you hear Scandinavia, Denmark, etc? Dairy! 

 Not everyone who lacks lactase enzymes has watery, frothy, bulky stools after eating lactose. The amount of lactose consumed and the transit time in the small intestines can make the difference between a skirmish and WWII in the colon. 

 The typical Western diet for an adult is about 300g carbohydrates a day, 5 percent of which consists of lactose (unlike infants, who get 50 percent of their calories from lactose). Milk and ice cream contain the most lactose, and cheese has less. Less than 8 ounces of dairy a day can reduce/prevent the uncomfortable GI symptoms. Lactase enzyme pills are over-the-counter and can be helpful to some. Eating a fatty meal can slow down the GI tract to reduce symptoms as well. Personally, I know I cannot drink a glass of skim milk (yes, I drink non-fat) without having food at the same time.

 I don't know if milkmen exist anymore, but I now buy organic milk and immediately put it in my fridge when I get home.


Dr. Hook cracks a joke or two, but he's a renowned physician with a local practice and an interesting website, drjohnhong.com. Email him with your questions.