Dairy products... are they good or bad for you? This is a question that has been one of the most debated things amongst the health and food sphere. Most interesting is that people seem to be extreme in their opinions on dairy products; its a hate or love kind of thing. There are few people who are neutral, or atleast they are not heard or seen in the forums discussing the issue.
Historically dairy products have been a major contributor to peoples survival. This is a fact that cant be denied. It becomes obvious when looking at the evolution of the european population. In northern Europe milk and dairy products have been an important food for centuries, and through centuries of consuming milk, a big part of the population have gained a mutation that let them break down lactose in a grown age. This is a typical example of selective selection.
Lactase is the enzyme that breaks down lactose. This is an enzyme that all new born can produce (less than 50 known cases of children that were born without ability to produce lactase) and it is needed to break down the lactose in the mothers milk. The ability to produce lactase usually stops in humans at age 6-8. But populations that have consumed milk for centuries got a mutation on the lactase gene, that makes them produce lactase through the entire life. This is only seen in areas where the consumption of dairy product been going on for a long time. The inheritance of the mutation on the lactase gene is not dominant, so it is no question about it; the ability to consume dairy products was a major survival advantage. In Scandinavian countries about 90% of the population has this mutation, and therefor has the ability to consume dairy products (with lactose).
How about now? The market for lactose free or dairy free products has exploded. Do we still need dairy products? Do they still have a place in our diet?
The fat in diary products are mostly saturated fat, generally this is bad for your health. Some new studies regarding that some of the saturated fatty acids in dairy products are not as bad as other saturated fat, but information is still lacking on the matter. And there are studies that claim that casein (a protein found in dairy products) could have negative effects on humans. It is also known that dairy products could alter the uptake of certain minerals and vitamins (like iron for example) in a negative way.
However, there are also studies on whey protein (a group of proteins also found in dairy products) have great health effects on humans. It is also known that both whey protein and casein has a high protein value and especially whey protein have a muscle anabolic and/or anti-catabolic effect. In other words dairy products are often a great source of protein, it is also very useful in cooking because of its organoleptic effects on the food.
So, what do I think of dairy products? I am one of the few that are neutral in the matter, even if Im often considered to be a pro-milk guy by the milk haters and a milk hater by the milk lovers :D
I think you should use it if you want and if you like it. I don't think you should be afraid of using it, or not use it because you heard that "casein are like glue" or "it is not meant for us to drink the milk of another species" (is it meant that we should eat the menstruation of other species (eggs)?) These are argument that lacks scientific evidence.
However, I don't think you should drink milk to your meals, especially not when you are eating something with iron (like blood pudding, meat etc). Iron deficiency is common and milk reduces uptake.
Here is a review article on the matter (yes I know it is sponsored, many studies are, it is however a good and well performed study):