This might seem surprising, but lactose intolerance is actually a normal condition which affects all mammals. Lactase is the enzyme that is produced by humans, (and other mammals) which is used to break down lactose, so that we can drink fresh milk and other dairy products. However, it is normally the case with all mammals that lactase production falls drastically after the 'weaning period'. In humans, this is equivalent to a drop in lactase production of roughly 90% after about four years. This results in the lactase stores in the human body being used up by adulthood, which means that most adults can only safely drink about 250ml of milk per day.

However, as always, there is an exception to the rule. A recent genetic mutation in humans has resulted in the gene that shuts down lactase production being suppressed, which means that lactose intolerance does not occur. The gene responsible for the continued production of lactose is a dominant gene, which means that it should continue to spread throughout the human population - good news for the rest of us. The mutation is most commonly attributed to either Sweden or the Arabian peninsula, although recently an argument has sprung up claiming that the mutation originated in Eastern Africa.

Since lactose intolerance is the normal state for most adults, a diagnosis is not really needed. However, there are ways to test for lactose intolerance if so desired. The most simple test involves preparing the night before, and then sitting for a breath test that lasts about two hours.

The preparation simply consists of not eating the night before the test - and no breakfast either. One then will have to drink a solution of water and 50 grams of lactose. If the lactose is not broken down, hydrogen will be produced and detected on your breath. A stool test for lactose intolerance also exists.

If you don't feel like visiting a doctor, one can always conduct an informal test - which has, obviously, a lower accuracy rate. It simply consists of having a couple of glasses of milk on an empty stomach, and then waiting to see whether you have stomach problems over the next couple of hours.

This finishes up the article on the diagnosis of lactose intolerance, hopefully it was informative.