Something I didn't know until adulthood, having inherited the northern European lactase-persistent mutation, is that it's not "normal" for most humans past weaning age to retain the ability to produce the enzyme lactase which is required to split the milk sugar lactose apart for digestion (in its absence lactose arrives intact to where your gut bacteria can and do digest it, giving off gassy waste products that make susceptible humans bloated and ill). So for me lactose per se isn't a concern but rather the total carbohydrate load of any given form of dairy, plus I wonder about the potential human effects of naturally present dairy hormones the mother animal produces intended for the growth of the young animal. Also some people struggle with various dairy proteins such as caseins. I've experimented with A1 vs A2 casein dairy with no definite personal results. Getting back to lactose intolerance, Lactaid milk has the lactose pre-split for those who don't produce lactase and want milk. Lactase supplements can also work.