For decades we've been encouraged to stay away from full-cream milk and other full-fat dairy in order to minimise our risk of heart disease. But research over the past few years has shown that whole milk is likely not that bad for you after all.
The Dietary Guidelines for Americans say you should substitute whole milk for low-fat and fat-free options. But now, according to The Washington Post reporter Peter Whoriskey, these US government indications on what to eat are receiving an update, and that will involve tackling a vital question - do saturated fats, such as those found in dairy, actually contribute to heart disease?
The reason we worry about saturated fats is cholesterol: the waxy substance that circulates in our blood, attached to lipoproteins. You've probably heard of 'good' and 'bad' cholesterol - this refers to high-density lipoprotein (HDL), and low-density lipoprotein (LDL) cholesterol, respectively.
The 'bad' stuff is what clogs our arteries, causing cardiovascular problems. The 'good' cholesterol, on the other hand, prevents cholesterol build-up and the associated troubles. And, according to guidelines, eating too much saturated fat causes 'bad' cholesterol to build up in the bloodstream.
However, a slew of recent studies have shown the situation with saturated fat isn't actually that clear. In 2014, a large review of studies that involved more than half a million people showed that saturated fat doesn't cause heart disease. In 2013, a report in the British Medical Journal stated there's no link between the two.
"Indeed, recent prospective cohort studies have not supported any significant association between saturated fat intake and cardiovascular risk," wrote cardiologist Aseem Malhotra. "Instead, saturated fat has been found to be protective."
Still, not all health experts agreed with this assessment. And it appears that the situation with saturated fat is more complex than we've been led to believe.
"Saturated fat is not just one fat, we know that different types of saturated fat vary from the harmless to those that are most definitely dangerous to heart health," Deakin University nutrition expert David Cameron-Smith from Australia said back in 2010. "The real question is identifying what saturated fats are dangerous by following different types of fat from food into our blood and then into the fat storage deposits of our body."
So, where does that leave us with milk? Fat found in dairy seems to be of the good kind. As Whoriskey writes:
"In 2013, New Zealand researchers led by Jocelyne R. Benatar collected the results of nine randomised controlled trials on dairy products. In tallying the tests on 702 subjects, researchers could detect no significant connection between consuming more dairy fat and levels of 'bad' cholesterol."
"There is no scientific basis for current dietary advice regarding dairy," Benatar told Whoriskey. "Fears [about whole milk] are not supported by evidence. The message that it is okay to have whole fat food, including whole fat milk, is slowly seeping into consciousness. But there is always a lag between evidence and changes in attitude."
Since whole milk isn't even that fatty, perhaps it's time to switch back to the good stuff.
But even if full-fat dairy goes back on your menu, the general advice is still to replace saturated fats in your diet with polyunsaturated as much as possible. "Countless studies show that if you replace saturated fat with polyunsaturated fat, you do get a reduction in heart disease risk," nutrition expert Alice Lichtenstein told Amy Paturel at WebMD.