I’ve wanted to address this one for a while.
I consider lactose intolerance to be one of the most universally mischaracterized and misunderstood concepts in all of nutrition and health. The most astounding thing is how deeply misunderstood it is by health experts, like doctors and nutritionists. It’s quite shocking how pervasive it is. So my aim is to take the basic principles of gut microbiome physiology that we regularly discuss on this blog, and use them to cut through what I consider to be a sort of mass delusion.
There’s a reason I put lactose intolerance in scare quotes in the title of this post. To me, there are really two concepts of lactose intolerance. I’ll start with the first one, which I call technical lactose intolerance.
Technical lactose intolerance is genetic. It means that your body, once it is past infancy, ceases to produce the lactase enzyme, which is required for breaking down and digesting the sugar carbohydrates in dairy (lactose) in the small intestine. But here’s the funny thing: what this really means is that you are a standard, run-of-the-mill human being. You see, technical lactose intolerance is actually the norm. It’s estimated that nearly 70 percent of the world’s population does not produce the lactase enzyme, making them technically lactose intolerant. Which makes the term lactose intolerance very strange. We usually reserve the word “intolerance” for something that should be tolerated but isn’t, like an allergy. It’s the lactose tolerant people — those who have the genetic mutation that allows them to produce lactase into adulthood and therefore digest lactose — who are the real oddities. Lucky duckies, they are.
Technically lactose intolerant populations, historically, tend not to consume much fresh milk. That we know. But notice I said “fresh milk” and not “dairy.” That’s because dairy consumption, in the form of cheese, yogurt and other fermented dairy products, is insanely prevalent throughout the world among technically lactose intolerant populations. It has been for ages. In fact, these dairy products were invented by ancestral populations who were assuredly lactose intolerant themselves.
Now hold that thought for a moment.
Let’s move on to the second type of lactose intolerance, what I like to call “lactose intolerance.” This is the kind of lactose intolerance that we most often hear about and discuss socially — at a dinner party, PTA meeting, with your doctor, in the news, etc. It’s the mainstream understanding of lactose intolerance: that your digestive system just isn’t equipped to handle dairy. Eat some cheese or yogurt (don’t even think about milk), and GI discomfort is bound to strike. You just aren’t built to handle it because of those crappy genes of yours. Nowadays, whenever you come across people who declare themselves to be lactose intolerant, they are almost undoubtedly referring to this type of lactose intolerance. And most doctors seem to accept and even propagate this understanding of lactose intolerance.
So what explains this dichotomy? Simple: the second type isn’t lactose intolerance at all. It’s dysbiosis.
If you remember, we have a pretty simple definition of what fiber is. It’s any carbohydrate that isn’t absorbed by your small intestine, and instead passes into your large intestine to be broken down and fermented by bacteria. Gee, isn’t that exactly what lactose is in a person who doesn’t digest lactose? Why yes, yes it is! Lactose, in people who don’t produce the lactase enzyme, is treated as prebiotic, fermentable fiber. You don’t digest it, so your gut bacteria do. Simple as that. In fact, lactose is known to be the preferential fiber for a pretty important class of gut bacteria.
And that’s what explains why lactose intolerant populations don’t generally consume much fresh milk, but plenty of fermented dairy products. That’s because a glass of fresh milk is quite a large bolus of lactose. A tall glass of milk might contain around 20 grams. For someone who produces lactase, that’s fine — it’s just sugar that will be digested. But for a non lactase-persistent person, that’s a lot of fermentable fiber. Which means it’s a limiting factor for how much milk you can consume in a sitting. But that’s the case with any kind of fiber intake, right? At a certain point, it will get uncomfortable, no matter how bulletproof your gut situation is. But yogurt, on the other hand, might contain around 7 grams of lactose per serving. Cheese? Even less. That’s because lactose is exactly what lactic acid-producing probiotic bacteria (ie, lactobacillus) consume in order to ferment these products. They drastically reduce the amount of lactose in them, which means you can comfortably consume much more of it without any discomfort. And that was probably pretty handy in the days when calories were a little harder to come by than they are today.
7 grams of lactose or less? Easy peasy. That’s a pretty decent prebiotic gut snack. Provided your gut isn’t a barren wasteland, that is! And yours truly is living proof: I am a technically lactose intolerant person. My body does not produce the lactase enzyme, confirmed by genetic testing (23andme). But guess what? I consume the hell out of dairy. Cheese and yogurt are daily staples. But that’s not all. Sometimes, I go ahead and do something crazy: I drink a glass of milk. If it’s a small one, not much happens at all. If it’s a tall one? Maybe I shouldn’t be too social that evening. And that’s exactly what technical lactose intolerance is: it’s just a limitation on how much lactose you can consume before things get less than comfy. Like anything else with a lot of fermentable fiber.
Which brings us to our modern “lactose intolerant” epidemic. You see, these people aren’t really lactose intolerant. They are fermentable fiber intolerant. Dairy gives them problems not because they lack a digestive enzyme, but because they lack their other 90 percent. Their gut bacteria just don’t seem to be able to handle even a small dose of lactose fiber.
Without doing too much research on this, I very strongly suspect that the entire concept of “lactose intolerance” is quite new and modern, relatively speaking. A hundred years ago, I don’t think anyone identified as “lactose intolerant.” Most people consumed dairy just fine. A subset of them — lactase producers — regularly drank fresh milk. But most people didn’t because they just weren’t culturally accustomed to doing so, and they probably knew it would make them kind of gassy and bloated if they drank a lot. And that’s that.
But probably right around the time we figured out how to royally screw up our guts and invite all manner of chronic ailments into our lives, a lot of people started to notice that dairy gave them problems in their tum-tum. But instead of figuring out why, we decided to just give it a name, blame genetics, and pretend like it existed since the beginning of time. Gee, does that sound like anything else?
Which leads me to believe that, just maybe, a gut rehab protocol could potentially cure this modern “lactose intolerance” epidemic sweeping the globe. If I had a problem digesting any amount of dairy, I would definitely try out a fiber adaptation regimen. It may be just the ticket to joining the ranks of us lactose intolerant, milk-drinking hermits.