From: AskDrSears.com
1. Yogurt is easier to digest than milk. Many people who cannot tolerate milk, either because of a protein allergy or lactose intolerance, can enjoy yogurt. The culturing process makes yogurt more digestible than milk. The live active cultures create lactase, the enzyme lactose-intolerant people lack, and another enzyme contained in some yogurts (beta-galactosidase) also helps improve lactose absorption in lactase-deficient persons. Bacterial enzymes created by the culturing process, partially digest the milk protein casein, making it easier to absorb and less allergenic. In our pediatric practice, we have observed that children who cannot tolerate milk can often eat yogurt without any intestinal upset. While the amount varies among brands of yogurt, in general, yogurt has less lactose than milk. The culturing process has already broken down the milk sugar lactose into glucose and galactose, two sugars that are easily absorbed by lactose-intolerant persons.
2. Yogurt contributes to colon health. There's a medical truism that states: "You're only as healthy as your colon." When eating yogurt, you care for your colon in two ways. First, yogurt contains lactobacteria, intestines-friendly bacterial cultures that foster a healthy colon, and even lower the risk of colon cancer. Lactobacteria, especially acidophilus, promotes the growth of healthy bacteria in the colon and reduces the conversion of bile into carcinogenic bile acids. The more of these intestines-friendly bacteria that are present in your colon, the lower the chance of colon diseases. Basically, the friendly bacteria in yogurt seems to deactivate harmful substances (such as nitrates and nitrites before they are converted to nitrosamines) before they can become carcinogenic.
Secondly, yogurt is a rich source of calcium - a mineral that contributes to colon health and decreases the risk of colon cancer. Calcium discourages excess growth of the cells lining the colon, which can place a person at high risk for colon cancer. Calcium also binds cancer-producing bile acids and keeps them from irritating the colon wall. People that have diets high in calcium (e.g. Scandinavian countries) have lower rates of colorectal cancer. One study showed that an average intake of 1,200 milligrams of calcium a day is associated with a 75 percent reduction of colorectal cancer. As a survivor of colon cancer, I have a critical interest in the care of my colon. My life depends on it.