So a big medical study hit the news recently. Apparently milk might not only not be good for you, it might be actively bad for you, at least if you drink a lot of it. (Though not that much. The articles all say the higher mortality rates are found among women who drank more than three glasses a day, but by “glass,” they mean 200 mL, which is less than a cup. So imagine three smallish Styrofoam coffee cups of milk, not three big glasses like you’d see in a milk ad.)
The TV news shows all covered it in the scientifically and statistically rigorous fashion that is their usual wont, hitting the following high points:
- “This is really only a problem for people who drink large amounts — really, enormous amounts of milk. Psht, who drinks three entire glasses of milk a day unless they own a cow?” (Hint: people following the current government-recommended guidelines.)
- “Let’s be balanced and discuss both sides. On one side, we have a doctor with a scientific study. On the other, we have the National Dairy Council, i.e., an organization funded by a tax on dairy producers to promote dairy products. Voila, balance!”
- “As a TV journalist who is obviously an expert in everything, I’m going to respond to the science reporter explaining this study by saying that I for one am confident that milk is the best thing out there to drink, nutritionally, and I know it’s good for me.”
- “As a doctor, I’m going to ignore the actual mechanism the scientists who did the study proposed, and suggest instead that the problem is that people are getting too much calcium. You don’t need more the one tablet per day, and there’s no need to use complex terms like ‘milligrams’ because obviously all tablets contain the same amount.”
- “Let’s run the current recommendations and past claims, context-free, in print at the bottom of the screen, even though they are directly contradicted by the study we’re reporting on.” (“3-4 glasses of milk a day cut osteoporosis chances by 20%” except this study is noteworthy because it found 3-4 glasses of milk a day significantly increase your chance of a hip fracture, at least if you’re a Swedish woman over 40.)
Fortunately, the study itself is available online and you can, if you want, read the whole thing.
The study was done in Sweden: in the late 1980s, all the women in two Swedish counties between the ages of 39 and 74 were recruited to come get a mammogram and fill out a questionnaire about diet and lifestyle. They followed as many of these women as possible, and the final study included over 61,000 women. The men were recruited later and followed for less time; the study also included fewer men (about 45,000). A whole lot of data was collected, and this study was done by reviewing that data — the information volunteered about their diets and lifestyles, and information gathered later on health problems and causes of death.
They found that the milk-drinking women were 15% more likely to die of heart disease, 60% more likely to get a hip fracture, and (this was the really shocking bit) almost twice as likely to die of any cause during the time covered by the study than the non-milk-drinking women were. The results among the men were less dramatic: they were 10% more likely to die, mostly due to increased heart disease.
The researchers think this may be due to the fact that D-galactose (one of the sugars that lactose breaks down into) causes inflammation and accelerated aging. They did consider the possibility of reverse causation, and checked to see whether women with a family history of fractures drank more milk (nope) and they ruled out some other possibilities as well, though “given the observational study designs with the inherent possibility of residual confounding and reverse causation phenomena, a cautious interpretation of the results is recommended.”
Helpful scientific study-to-English translation guide: “Residual confounding” is the technical term for “stuff we forgot to account for that screwed up our data.” “Reverse causation phenomena” means “we were thinking that A causes B, but it turns out that B causes A.” “A cautious interpretation of the results” means “don’t stop drinking milk on our account.”
Let me just note again — since if you heard about this on TV you doubtless heard someone reassure you that they’re talking about people who drink enormous amounts of milk — that the heavy milk-drinkers in this study might still have been drinking a half-cup less than the USDA daily recommendation.
Frustratingly, some of my most pressing questions were left un-answered even after I looked at the study.
1. This study was done in Sweden. If you’re a non-milk-drinking Swedish person, what would be your typical beverage at dinner? The study did find that as milk consumption increased, alcohol consumption tended to decrease, so maybe aquavit is really good for you? I’m going to hazard a guess that Americans who don’t drink milk are often drinking soda or diet soda. Galactose may be bad for you but high-sucrose corn syrup is not exactly health food. Nor aspartame, sucralose, or saccharin.
2. What sort of milk do Swedes drink? The study made no distinction between skim, two percent, and whole milk.
3. They said they found benefits to consuming “fermented dairy products” such as yogurt and “fermented milk.” My burning question here is, what are these Swedes actually eating? Because I’m guessing it’s not Yoplait or Activia or any of the ultra-processed sugar-laden yogurts most American yogurt-eaters consume. Also, by “fermented milk” are we talking buttermilk, or something else? A little bit of research turned up a Scandinavian dairy dish called filmjölk, which is apparently a kefir-like cultured dairy product popular in Sweden. Apparently you can buy it at the store and you probably sweeten it with sugar, jam, or fruit. You might also eat it with granola. Wikipedia seems to think that non-fat filmjölk is not a thing. And can I just say that they are right on about that? Low-fat yogurt is fine. Non-fat yogurt is nasty. Non-fat Greek yogurt should be grounds for a lawsuit from the entire nation of Greece.
4. Most importantly, what the hell are they feeding the cows in that part of Sweden? Radioactive waste? Because there have been approximately ten kajillion studies on milk in the past that have found either modest benefits or no significant harm. These milk-drinking Swedish women were almost twice as likely to die over the course of the study as the non-milk-drinking Swedish women. These are the sorts of hazards I’d expect to see associated with cigarettes, large quantities of whiskey, and doing asbestos removal without protective gear, not drinking milk. If milk is really that bad, how have we not noticed this before?
Maybe it’s been covered up by some sort of global dairy farmer’s conspiracy? A lot more Googling of past research turned up a lot of stuff about how maybe calcium doesn’t actually do much to prevent hip fractures, and even if you look at the health benefits claimed for milk by the American Dairy Council, if you follow up on the sources, you’ll find a lot of shrugs and statements about how it doesn’t seem to harm you and maybe there’s a marginal benefit. But that’s still a far cry from (almost) doubling your risk of death.
One of the things I noticed as I waded through this slightly surreal mix of propaganda and science was that pretty much everyone agrees that Vitamin D is really good for you. Calcium supplements probably don’t prevent hip fractures, but Vitamin D supplements definitely do, and a number of the benefits people will attribute to milk are actually from the Vitamin D, which is not in there naturally. American milk is routinely fortified with Vitamin D, and has been since the 1930s. Which got me wondering: do the Swedes fortify their milk?
As it turns out, not until the 1990s — well into the study.
So. What is the take-home lesson here?
First of all, if you don’t like milk, definitely don’t feel like you should be drinking it. The health claims for milk are mostly pretty tenuous.
Second, you should probably be taking a Vitamin D supplement.
Third, if you’re a Swedish woman, maybe you should switch to aquavit.