Gas, bloating, stomach pains...that’s what some people experience after drinking milk. And we’re not talking about an occasional problem; some seventy percent of the world’s population can’t handle lactose, the naturally occurring sugar responsible for the sweet taste of cow’s milk. The reason is a deficiency in the enzyme, beta-galactosidase (better known as lactase), which is essential for breaking lactose down into its components of glucose and galactose. If this isn’t done, the undigested lactose moves into the large intestine where bacteria use it as food. Such fermentation results in the formation of gases which cause bloating and cramps. One of these gases is hydrogen, which forms the basis of the standard test for lactose intolerance. A patient is asked to drink a standard amount of lactose solution and the amount of hydrogen produced is then measured via a breath test. This is the only way to determine if someone is truly lactose intolerant.
Lactose intolerance is most prevalent among people of Asian, African and to a lesser extent, Mediterranean origin. Many parts of the Asian and African continents were once afflicted by sleeping sickness, a disease transmitted by the tsetse fly, and responsible for the destruction of most cattle populations. Geneticists believe that the resulting unavailability of milk in these areas led to lactose intolerance. In terms of evolution, such a response would be appropriate, since disruption of the synthesis of a non-required enzyme would be energetically advantageous to the human body. Although lactose intolerance is rare among infants, the ability to produce the enzyme drastically decreases during the years after weaning in predisposed individuals. Even lactose intolerants, however, can usually consume a single glass of milk (about 15 grams of lactose) without the serious ill effects normally associated with the condition.
Since milk is the most common dietary source of calcium, people suffering from lactose intolerance are often calcium deficient. In this case, cheese and yogurt should be included in the daily diet as substitutes for milk. One ounce of cheddar cheese provides as much calcium as one cup of milk, but less than one tenth as much lactose. A preparation containing the missing enzyme is also now commercially available under the name of Lact- Aid. A few drops of this solution can be added to milk, leading to the destruction of most of the lactose within 24 hours.
The above strategy will still restrict a person's diet outside the home or when it comes to satisfying that "sweet tooth" for ice cream, chocolate pudding or a creamy custard cake. However, a preparation of the enzyme, in a tablet form, can be ingested with the meal to prevent the feared side effects. This Lact-Aid pill supplies the enzyme needed to break down lactose in the small intestine. Who said you can't have your cake and eat it too?