MILK AND NUTRITION
If we consider how and when milk is produced by the animal, it is clear that this drink is designed for the newborn specimens. Especially when we consider the content of lactose in the milk - the sugar that only can be digested by lactase, which is an enzyme that most of the people only produce during their early weeks of life. In other words, milk can be said to be baby food, as it is rich in nutrients that optimize the growth of the new life - protein, fat, calcium, and even antibodies to fight off possible infections when the immune system has not yet fully developed. Milk really only lacks iron and vitamin C, which may be provided from other foods. In any case, being the perfect baby food, we still consume milk and the dairy products as grown up adults.
One obvious problem arises with milk consumption. As just mentioned, lactose cannot be digested by most of the people, and so it causes intestinal problems. Bacteria in the large intestine break down the lactose instead of our own digestive enzymes, but the result is different - gases like carbon dioxide, methane and hydrogen are produced and cause swelling of the intestine. On top of this, milk lactose, when not sufficiently digested, draws out water from the intestinal walls into the intestine, which causes diarrhoea. These problems are known as lactose intolerance. Nowadays though, lactose intolerance can be dealt with by simply buying lactase that can be added to the milk before it's consumed. We should also remember that not all dairy products are rich in lactose - yoghurt for example is made by lactose-digesting bacteria and can be eaten to a larger extent than the usual one cup of milk before lactose intolerance symptoms appear. Also, Swiss cheese or cottage cheese contain relatively low amounts of lactose.
A big argument for milk consumption throughout the years was that it contains a lot of calcium, which is needed for the build up of our bones, especially during the early life. Women after menopause also need extra calcium due to the lower production of estrogen, normally a bone-forming promoter. But can't we use any other calcium sources except milk and dairy products? Of course we can, and we should, because drinking too much milk while setting aside other types of foods can be health-damaging. Calcium-rich foods that also add variety and other nutrients to our food are broccoli, egg, turnip greens, soybeans and other beans, nuts, and also the calcium-fortified products (cereals, fruit juices). At the same time we should avoid eating too much salt and animal proteins that tend to excrete the calcium from our bodies.
In summary, milk has its advantages and disadvantages. On the bright side is its varied and nutritious content, but on the other hand, too much milk can create problems. The conclusion then is to simply eat a moderate amount of milk products, not forgetting about other foods - especially calcium-rich vegetables that also provide other nutrients.