There are lots of myths and misunderstandings out there about dairy. I went to a vegan-oriented event recently and though most of the information imparted was interesting and valid, there were a few "facts" confidently espoused about dairy which had me scribbling big question marks in my notebook.

Some you may have heard, or read online, where you can find lots of this kind of thing. There are also some "documentaries" on Netflix which offer a pretty slanted – and less than scientific - view on this topic.

"Humans are not supposed to drink cow's milk" is one example. The explanation? We are not "designed" for it. How can we consume milk that's meant for the babies of another species?

This seems to be partly an emotional argument – it's gross to drink what's meant for baby cows – and also related to the issue of lactose intolerance.

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It's true that lactose intolerance – an inability to digest lactose, the sugar in milk – is an issue for over half of the world's adults. In some populations, such as in people of East Asian descent, up to 90 per cent of people are lactose intolerant. On the other hand, in people of Northern European descent, only around 5 per cent of people are intolerant. That's because European populations have developed the ability to digest lactose after infancy, most likely because they've been eating milk products for thousands of years. They've adapted to be able to eat milk, yoghurt and cheese because those foods have been staple foods for a long time. So while you could say some of us are not "designed" to eat dairy, some of us have adapted our design to do just that.

Whether or not you think drinking milk is gross is a personal thing, really. It's true we don't need milk; we can survive without it. But it is still a pretty good and useful food.

There are lots of myths and misunderstandings out there about dairy. Photo / Getty Images
There are lots of myths and misunderstandings out there about dairy. Photo / Getty Images

Milk and dairy products contain nutrients that are beneficial not just for cows. It's full of protein and calcium; the latter in particular is an important mineral for bones, and dairy is the main way we get it here in New Zealand. We establish our bone density when we're young, so it's really important for young people, especially girls, to get enough calcium when they're growing. Though it's possible to get the calcium we need from other foods – it's in some vegetables, chickpeas and seeds, for example – it's much harder to do, and you're going to have to be very careful and well-planned with your diet. So if your teenager has developed a taste for almond milk, at the very least make sure you're buying one that's calcium-fortified.

A new dairy theory – at least to me – is that cheese is addictive.

I'll admit as a cheese lover I can sometimes feel unable to step away from the cheese platter, but until recently I had not heard of the existence of casomorphins – apparently addictive compounds in dairy. The theory goes that the casein in milk contains casomorphin fragments, which are morphine-like compounds, and these fragments attach to the same brain receptors that heroin and other narcotic drugs attach to. Therefore: cheese is addictive.

Though that sounds alarming, having a love for cheese is really not the same thing as being addicted to hard drugs. Neuroscientists have described this line of thinking as a huge oversimplification; yes, casein does affect the opioid system; we're designed this way. It's pretty useful when we're infants that we have a liking for our sole diet of breast milk.

But in studies measuring the addictive-like properties of foods, cheese on its own does not figure highly. A 2015 study looking at which foods were most associated with addictive-like eating behaviours found pizza, chocolate, chips, cookies and ice cream were the top five problematic foods; the researchers say this is because they're all highly processed foods, or foods with added amounts of fat and/or refined carbohydrates.

Cheese on its own was at number 10 on the list – but there was no mention of casomorphins. It's probably fair to say that cheese addiction is not really a serious thing.
You may also have heard things about dairy being a cause of inflammation, and possibly diseases such as cancer and arthritis. It's impossible to go into all of that here, but it does seem as if it would be pretty easy to cherry-pick studies that support one side of any of these arguments or the other; there seems to be evidence on both sides.

I am reassured by the Cancer Society's position on dairy, though, which is that while dairy foods seem to give protection for some cancers but increase the risk of getting some others, overall, the proven health benefits of dairy foods outweigh the unproven harms.

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So: bottom line? We don't have to have dairy foods to be healthy, and if you choose not to eat these, that's fine. But if you like dairy, you can enjoy your milk, cheese and yoghurt happily and in moderation as part of a varied diet.

Niki Bezzant is editor-at-large for Healthy Food Guide www.healthyfood.co.nz