Some claim that drinking the milk of other animals—or drinking milk beyond infancy—is both unnatural and unhealthy. How do the arguments for and against consuming milk stack up?
I recently got a note from Diane, who was upset with me for supporting the consumption of dairy products.
“No human should be consuming milk after they've been weaned from their mother's breast,” she wrote. “It is completely unnatural. Cow’s milk is intended only for baby cows—and it’s cruel to take the milk away from the calves for whom it is clearly intended. Need calcium? Milk, which may contribute to osteoporosis and numerous other health issues, is the last place you should be getting it.”
Before I respond to Diane’s remarks, I just want to repeat something I’ve said many times before: Drinking milk is not necessary for good nutrition (or strong bones) and I completely support anyone who decides for whatever reason that they don’t want to consume it. If you’ve decided you don’t want to drink milk, I am not going to try to talk you into it.
If, on the other hand, you ask me about the benefits or risks of dairy (or any other food), I will try to give you a balanced and evidence-based answer, so that you can base your decision on good information.
I’ve certainly heard these arguments against drinking milk before. Maybe you’ve heard them too. Maybe you’ve made them! Often there is a lot of emotion involved, which can make it hard to have a productive conversation about this issue. But I’d like to try.
Although they are often all jumbled together, there are actually three completely different arguments being presented here.
- Drinking milk is unnatural
- Drinking milk is unhealthy
- Drinking milk is cruel
It’s possible to accept or reject one of these arguments without accepting or rejecting them all. So, let’s consider them one by one.
1. Is Drinking Milk Unnatural?
I would submit that the natural world does not operate with intention, nor is it all that attached to a plan. In fact, some of Nature’s greatest hits are the result of random errors and unintended consequences. Nature also doesn’t care about right or wrong, or whether something is fair or ethical or cruel. All nature "cares" about is what works.
If a bird lays an egg that hatches into a baby bird, which matures and lays another egg, that works for Nature. But if that egg is stolen out of the nest by a hungry raccoon who goes on to reproduce, that works too. Nature isn’t rooting for the bird more than it is rooting for the racoon. In fact, if Nature were actually capable of rooting for anything, it would probably hope that just enough eggs would be stolen to ensure plenty of baby racoons AND plenty of baby birds.
To the extent that consuming dairy enhanced the survival and reproduction of prehistoric humans, who then committed resources to enhancing the survival and reproduction of dairy animals, the fact that humans learned to use the milk of other species has worked out pretty well for Nature. So much so that some branches of the human family evolved to continue to produce milk-digesting enzymes throughout adulthood.
The objection to things that are not natural also seems to be somewhat selective. If you are willing to switch on a light after the sun goes down, use an alarm clock to wake you up, get in a jet plane and catapult yourself across three or four time zones in a few hours, run long distances without anything chasing you, or take a vitamin pill, then you’re doing quite a few things that are arguably a lot less natural than drinking milk.
The fact is that mother's milk contains nutrients that benefit animals other than that mother's babies—and it would be unnatural for those other animals to ignore that discovery.
2. Is Drinking Milk Unhealthy?
Just about anything can be consumed in quantities (or contexts) that make it harmful. But are dairy products bad for you when they are consumed in the context of a balanced and nutritious diet? Do they cause heart disease, cancer, or other diseases?
Diane specifically mentioned a correlation between dairy consumption and osteoporosis. But just because two things occur simultaneously does not mean that one thing causes the other. In this case, there are several more likely explanations for why these populations might have higher rates of osteoporosis, including genetics, activity levels, and other aspects of diet and lifestyle.
When we compare people within these populations (instead of across them), milk and dairy consumption are associated with better bone health—which makes sense, because milk is an excellent source of absorbable calcium, vitamin D, and other nutrients that help to build strong bones.
Others have claimed that drinking milk causes breast cancer, an argument based mostly on animal or test tube studies and observations gleaned from a single highly unrepresentative population.