Maybe it's because huge dairy intake doesn't prevent it ?
Another article in New Scientist a decade or so ago held that some US scientists had discovered a way of feeding dairy cattle that improved the fatty acid profile, and lead to greater quantities of Calcium, Magnesium, zinc, and other trace elements in the milk.
Strangely enough, this miracle diet was pasture.
All of the food "standards" regarding nutrition that were established in the middle of last century need to be revisited in line with modern agricultural techniques. Almost nothing grown these days has the same nutrative quantities as originally farmed.