Associate Professor Louise Brough: Milk is a great food source. It’s very nutritious and contains lots of things that we need, like the macronutrients, which provide energy, fat, carbohydrates, protein.
But it also contains lots of what I’m interested in, which is micronutrients, so that’s your vitamins and your minerals.
We need to consume milk obviously when we’re babies, and so do infant animals. We don’t need to consume it when we’re older, but it is such a good source of nutrients – why not?
In milk, vitamin D is really important because it helps us to absorb calcium, helping our bones to develop and to maintain bone health.
It’s also got Vitamin A, which is really important for eye health, immunity and a whole load of reasons.
Of course, not everyone can drink milk – why is that?
Associate Professor Louise Brough: Lactose intolerance means you can’t break down the lactose in milk – you don’t make the enzymes that you need to break it down in your gut.
Instead of those smaller sugars being absorbed into the small intestine, they get into the lower intestine, into the bowel, and then they’re basically consumed by the bacteria.
They’re fermented, which produces gas and bloating, and that’s what gives you the stomach pain and problems.
There’s actually more people in the world who can’t consume milk than can consume milk because it’s actually a genetic defect.
If you think about it biologically, we probably shouldn’t be consuming milk post-weaning, but because we’ve had these populations that have been consuming milk for millennia, the genetic defect, if you like, was allowed to keep growing, and so parts of the population evolved so that they could have milk.
That’s why you have quite distinct areas like parts of China, parts of Africa, where a huge amount of people can’t consume milk because they have this lactose intolerance.
But a lot of Western and Middle Eastern people, parts of India, we do produce the enzyme lactase, which we need to help us break down the milk sugar.
Massey nutrition expert Louise Brough says cow’s milk is a nutrient-rich option, though not everyone can tolerate it. Photo / Christine Cornege
Are all milks equal?
Associate Professor Louise Brough: All milks are different and each milk for each specific mammalian species is very different because it’s based on what that infant needs.
Cow’s milk is very different to human milk, and when we want to make infant formula from cow’s milk, we have to change it an awful lot. It’s the same with, you know, goat’s milk or sheep’s milk.
I wouldn’t say that one’s actually better than another.
I think what we do see in some animal-based milks is that some people, perhaps for unknown reasons, are able to tolerate certain milks better.
So I guess it’s just up to the individual. If an individual finds that they get gastric symptoms with cow’s milk but don’t with sheep’s milk, well then, why not have the sheep’s milk?
What’s A2 milk?
Alex Irvine of Canterbury’s Choice says, “The way I describe it – we break it down a lot slower in our digestive system. So with A1 protein – imagine a bunch of little dots – your enzymes have to immediately try to break those down in your digestive system. Whereas A2 protein is more like a solid bar, and we sort of slowly chip away at breaking it down. So it’s a lot easier on our stomachs.”
Associate Professor Louise Brough: A2 milk has actually more to do with the beta-casein and it’s not really to do with the lactose.
It seems to be there’s something about the casein molecules in the A2 milk, which have less adverse gastric effects. The reasons why, I think we’re not quite sure about, but definitely, there have been clinical trials that have shown that you get [fewer] gastric symptoms.
How does sheep’s milk compare?
Cameron Ravenwood of Fernglen Farm in Wairarapa says: “Sheep’s milk is really good from a digestibility perspective. So basically it’s all A2-type protein, which research suggests that it’s easier to digest compared to milk that contains A1 and A2 beta-casein. It’s also [got] medium to short fatty chain acids as opposed to long fatty chain acids, which is in cow’s milk, so it’s just quicker and easier to digest. Nutritionally, it’s got around 60% more protein and calcium compared to cow’s milk. It’s high in like magnesium, phosphorus, zinc – basically all your micronutrients.”
Consumers have more choice than ever, from cow’s milk to goat-, sheep- and plant-based options.
Associate Professor Louise Brough says: There was some research which found the differences in the chain length of the fatty acids might be a reason why it’s easier to digest. It does have lower lactose.
It does also have more micronutrients and higher protein than cow’s milk, which means you can get more energy.
I guess the slight issue with it is it is quite high in fat, so you are going to get more calories, so people who are watching their calorie intake need to be aware that it is higher in fat than the other milks.
That’s what makes it so creamy and so delicious, though. It makes nice cheeses because of this, too.
Is it similar for goats’ milk?
Frans Steenkamp of the now-closed Brooklyn Creamery in Wellington says: “People come back and they say it’s gentle on the tummy. They can actually handle using the milk in their coffee and their cereal and they don’t get upset tummies. It’s naturally A2 and it’s lower in lactose, naturally lower in fat. So when you drink the goat milk, it’s got a very delicate texture to it.”
Associate Professor Louise Brough: It’s a lot like sheep’s milk. It is lower in fat and lactose. Like I say, it can be gentler on the stomach for some people – there is anecdotal evidence that people do tolerate it better.
What about plant-based alternatives?
Dr Gert-Jan Moggré, the man behind the Bioeconomy Science Institute’s (formerly Plant & Food Research) barley dairy project, says: “Beta-glucan is a beneficial fibre that is high in this product, so it’s more than just general fibre, it’s that beta-glucan, which can bring a health benefit.”
Associate Professor Louise Brough: Betaglucan is what we call a prebiotic. So we don’t digest it ourselves, it gets into the lower bowel, and then it’s fermented or consumed by bacteria there, and it produces things which help to improve our health.
It’s also in oats and rye by the looks of it.
Plant milks are very different to animal milks and there is some discussion as to whether we should really be allowed to call them milk because they are so very different.
They definitely don’t have the lactose in them, so if you have lactose intolerance, then they’re a good alternative.
Typically, they don’t have as much energy or protein in them and they are lacking in a lot of those micronutrients.
Here in New Zealand, most of the plant milks are now fortified with calcium, so you’ll get the same amount of calcium in a plant milk as you would in an animal milk. If they’re fortified, that’s not a problem.
One thing is that plant milks can contain what we call anti-nutrients – things that can stop you absorbing minerals like iron or zinc because of compounds called phytates.
Of the plant-based milks, soy is the most nutritionally complete – though there are also people allergic to soy.
Rice milk has the lowest energy, while almond milk has the highest fats so it possibly has slightly more energy than some of the others.
That’s from a nutritional perspective – there are also environmental factors.
We’ve also seen that people use milks differently – so there are maybe milks people wanted to put in their coffee, or their breakfast cereal or in a smoothie.
I think mixing plant milks with animal milks is a good way to get the milks that you like the flavour of and also still get all the nutrients that you need.
*Responses edited slightly for brevity and clarity
– RNZ