Answers to Questions from Readers, part 11

Q. Have you heard of a dairy allergy with no other symptoms at all, except a badly upset stomach?

Yes. There are two types of allergy. A "true" allergy is mediated by one particular antibody. All the others, or hypersensitivities, are mediated by other antibodies. Hypersensitivities to milk in children are likely to manifest themselves as gastrointestinal problems rather than as classic respiratory and skin problems. So it could be a reaction to the dairy protein rather than to the milk sugar. Your doctor should be able to test for this.

Q. When I drink beer, I have some of the same symptoms as when I drink milk. Is there some sort of dairy product in beer?

Most beer does not contains lactose. But Drew K. wrote me to say:

I have a friend who is a great brewer of beer, and he tells me that any beer with the word "Cream" in it such as "cream stout" actually has lactose in it. He knows, he adds the lactose himself to his "cream" beers! The milk sugar is added to the mix b/c it gives some sort of special twist to the flavor and fermentation. Is there any left over when you drink it? I don't know, but I suspect yes.

Drew's suspicions are correct, as I wrote in Lactose in Beer.

You won't be surprised to learn that it varies too much with the recipe for a definitive answer. I did a calculation from one recipe and found that it resulted in about half as much lactose as a glass of milk. Other sources say, however, that the lactose content is small for some milk stouts. If you drink for flavor and not a buzz the lactose shouldn't be a problem.

It most probable that it's the alcohol that's affecting you, since alcohol is definitely a known cause of all sorts of problems in all sorts of people. If it bothers you enough, stop drinking beer.

Q. I have heard that black males experience LI at a much higher rate than white males. Is this true, and if so why?

This is mostly true. In general, the only peoples in the world who are not lactose intolerance are northern Europeans (or are descended from people originally from northern Europe). All others cultures are predominantly LI.

The brief explanation is that the first farmers to arrive in northern Europe about 5,000 years ago lacked a good way of getting and processing calcium in their bodies. Those who could drink milk had a slight reproductive advantage over those who couldn't. (Women were more likely to survive childbirth, men were more likely to be healthy enough to father healthy babies.) The northern Europeans happened to be the ones who colonized America, so most people grew up thinking that the ability to drink milk was normal. Africans, as well as Asians and Native Americans, either had other sources of calcium, or could use the abundant sunlight to manufacture vitamin D in their bodies to help them process the calcium, so they didn't need to adapt to milk drinking.

The situation is far more complicated than I can describe here, of course. There are African peoples who because of local conditions had the same dilemma as the Scandinavians and solved it the same way, by natural selection favoring those who drink milk. There is nothing about skin color that inherently determines whether you are LI or not. It's a remnant of what your ancestors ate thousands of years ago. Note that lactose tolerance is a dominant trait, so that people whose parents are from mixed cultures tend to be lactose tolerant themselves. With the increasing rate of intermarriage in all areas of the world, the percentage of people who are LI is likely decreasing with each generation.

Q. Can wheezing and a stubborn dry cough be a symptom of lactose intolerance?

Not a chance. It's barely possible that the wheezing could be due to a dairy allergy (some people believe that a dairy allergy can cause any symptom), but that would really be reaching. Sometimes a cough is just a cough. If it lasts and lasts, see your doctor.