Milk is a richly nutritious mixture of water, proteins, minerals, vitamins, sugars, saturated fat and cholesterol. All mammals make it, but humans are the only ones to drink it beyond their early years. Should we?
Breast milk – or synthetic versions of it – provides the “perfect balance of nutrients” for babies in their first year, says Andy Bernstein, a paediatrician at Northwestern University in Evanston, Illinois. After that, full-fat cow’s milk is recommended as a good source of fat for brain development, dropping to 1 or 2 per cent fat milk from age 2.
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Read more: Good hydrations: From water to wine, how drinks affect health
We swallow 1.7 litres of fluids on average a day – and with them a lot of myths about what is, and isn’t good for us
But although programmes in the US and UK that gave milk to children in schools were associated with huge health benefits, it is not clear why. “We don’t know if there is something specific or special about milk, or if it is just the fact that these children are getting more calories, protein, nutrients in general,” says of the University of Indiana at Bloomington. A recent study of children in Kenya found that supplemental milk helped those with stunted growth catch up in height, but provided no benefits over a non-milk nutritional supplement for children developing normally.
For adults, the benefits seem even more dubious. There is no conclusive evidence, for example, that getting extra calcium from milk is or . Other foods besides milk – “beans and greens”, largely – are also rich in calcium, and most researchers now argue that a generally healthy diet and plenty of weight-bearing physical activity is what keeps bones healthy.
“All mammals make milk, but only humans drink it as adults”
And we should perhaps be careful not to overdo the white stuff. A Swedish study published in 2014 found that drinking three glasses of milk a day over an average of 20 years compared with drinking just one – while showing that consuming fermented milk products such as yogurt and cheese reduced both fracture risk and overall mortality.
The authors of that study recommend caution in interpreting the results, though, as there were a number of potentially confounding factors they couldn’t control for. The fermentation finding is not fully understood either, says Amy Lanou of the University of North Carolina at Asheville, although it might have something to do with a reduction in the milk sugar lactose during fermentation. “If some of these effects are mediated by milk sugar, that may be a reason,” says Lanou.
Soya milk
If cow’s milk isn’t necessarily all that healthy, what about its most common substitute? Soya milk has a bit less fat than cow’s milk, but often comes pre-sweetened, counting towards your intake of free sugar. Its reputation for is overblown, too – even if you drank about eight glasses per day that would only equate to a 3 per cent drop in LDL.
Other supposed health benefits – preventing breast and prostate cancer, reducing risk of osteoporosis and hot flushes associated with the menopause – are ascribed to soya milk’s high levels of compounds known as phytoestrogens. These can mimic the effect of the hormone oestrogen or, in some instances, block it. But none of these effects has been convincingly demonstrated in trials, while a may actually increase breast cancer risk.
Organic or non-organic?
Organic milk contains higher levels of omega-3 fatty acids than non-organic milk: it comes from cows that eat more grass, which is high in these acids. But even with this boost, total levels of omega-3s are still low in organic milk. And neither kind is allowed to have any traces of antibiotics.
Another common reason to go organic is fear about hormone levels in non-organic milk. All milk naturally contains hormones, but in areas where cows are treated with growth hormones – as happens in some US states but not in the European Union, Canada, Australia and New Zealand – non-organic milk may have higher levels of insulin-like growth factor, a hormone linked to increased risk of some health problems. But the US Food and Drug Administration concluded that it poses no health risk at the levels present in mass-produced milk.
This article appeared in print under the headline “Milk”
