We have been drinking it for thousands of years, and for longer than any of us can remember it has been promoted as one of the healthiest foodstuffs around. But increasingly, milk is in the firing line.
Could insidious, cancer-causing substances really lurk within something we know as being packed with vitamins and minerals and all-round goodness?
The latest item for the prosecution case came this week with news that a study of more than 60,000 women has found those drinking more than two glasses of milk a day were at significantly greater risk than the rest of the most serious form of ovarian cancer. The research, carried out in Sweden and published in the American Journal of Clinical Nutrition, found the risk was the same whether the women were drinking full-fat, semi-skimmed or skimmed milk. Around 4,690 women die in the UK every year from ovarian cancer, a notoriously difficult disease to treat: what's more, this isn't the only study to suggest a dairy link.
And there's more. Papers have already been published on a possible link between dairy products and the development of breast and prostate cancers; high-fat milk products are known to raise levels of cholesterol, a contributory factor in heart disease.
There are snorts of derision at this over at the UK's Dairy Council, where everyone remains convinced of milk's health-giving qualities.
But not everyone is so confident: at Bristol Royal Infirmary in south-west England, Jeff Holly, professor of clinical science, believes the tide is turning, and that the newest research is just one block in what will eventually become a large wall of evidence that, pure and spotless though it might look, milk has its bad side too.
"There's a convergence today that's questioning how healthy milk really is. I'm cautious because we don't want these studies to be exaggerated, but a lot of researchers are looking at a lot of questions," Holly said.
"What we've seen in recent years is that it's been implicated in more and more studies -- and while people might say, `Surely it can't be bad, we've been drinking it for centuries,' the fact is that, in evolutionary terms, it hasn't been part of our diet for that long," he said.
The proportion of our diet made up of dairy products has increased over the years, and the way milk is produced in recent years has changed a lot, and that could all be part of the problem.
The problem with humans drinking cow's milk, Holly said, is that it is biologically designed for a very different function: to boost the growth of small cows at a time in their lives when they need to grow quickly to become big cows. And this is significant, because while there are lots of questions to be answered over possible links between milk and cancer, the finger of suspicion points most persistently at growth factors and at proteins within milk that stimulate the development of growth factors in human bodies. What some scientists believe is that the growth factors that were intended to make baby cows grow could have a role in providing the right environment for human cancer cells to grow, too.