People often claim they’re lactose intolerant. But few people know for sure because few people have been tested for it.
I am one of those lucky, lucky few. For some reason (sadism?), a doctor subjected me to the test many decades ago. I even lived to tell about it.
And what I have to tell you is this: if you are truly lactose intolerant, the test is a cruel one. The way it works is that you fast overnight and then they take some blood and determine your fasting blood sugar. There are newer tests that don’t involve blood drawing, but they all involve the next step, which is the crucial one as far as I’m concerned: they give you a nice big drink of lactose.
Ever drink a lactose solution? It’s not all that pleasant, but the taste is not really the problem. A huge glass of it—I can’t recall whether it was 12 ounces or 16, but whatever it was it was a lot—can be swilled down even by those who hate milk, as I do. But if you really are lactose intolerant, it means you cannot digest the lactose in it, and there’s an awful lot of lactose in it, and so…well, you figure it out. Suffice to say you become very ill, and the bathroom becomes your very best friend.
Every half hour after ingesting the stuff (or was it every hour?) you return to the lab for another blood drawing. The idea is that if you are actually absorbing the lactose, which is milk sugar, your blood sugar level will rise initially and then fall over time in a certain pattern. This will determine not only whether you are in fact lactose intolerant, but to what degree.
For those of you who don’t know how lactose intolerance works, here’s the scoop:
Most mammals normally cease to produce lactase [the enzyme that digests milk], becoming lactose intolerant, after weaning, but some human populations have developed lactase persistence, in which lactase production continues into adulthood. It is estimated that 75% of adults worldwide show some decrease in lactase activity during adulthood. The frequency of decreased lactase activity ranges from 5% in northern Europe through 71% for Sicily to more than 90% in some African and Asian countries. This distribution is now thought to have been caused by recent natural selection favoring lactase-persistent individuals in cultures in which dairy products are available as a food source.
When my results became available I was told by the doctor that, unlike most people who are lactose intolerant, I had absolutely no rise in blood sugar level, which indicated I am completely lactose intolerant. That is, I don’t seem to be able to squeeze even a smidgeon of lactase out of my gastric spigots. And yet in fact I can ingest a certain amount of ice cream without too much difficulty. Where there’s a will there’s a way, I guess.
The whole thing reminds me of the fact that those who suggest that everyone would do well to eat a certain diet—such as, for example, the so-called “paleo” diet—because humans evolved on that diet are ignoring the many thousands of years of human adaptation and evolution since then. Lactose intolerance is almost unheard-of in northern Europeans, for example, and very common in people of Mediterranean origin. It rises to a high of 80% to 90% of Asians, African-Americans, and Jews.
I always hated milk, anyway, even as a toddler. It tasted so, so…milky. So being lactose intolerant is no biggee for me.