Does milk prevent colon cancer?

Although laboratory studies on animals and humans have shown that milk reduces the number of carcinogens in the faeces, in a recent survey of more than 100,000 people in the Netherlands, consumption of dairy products was associated with only a minor reduction of cancer risk (Cancer Res, 1994; 54: 3186-90). In an attempt to single out the factors in milk responsible for this small protective effect, a Harvard study of nearly 90,000 American nurses found little or no effect of dietary calcium, whereas vitamin D halved the incidence of colorectal cancer (J Natl Cancer Inst, 1996; 88: 1375-82). However, higher levels of calcium in the water supply (more than 42 mg/l) appeared to reduce colon cancer incidence by nearly 50 per cent (Jpn J Cancer Res, 1997; 88: 928-33).

Because dairy products have been linked with other cancers, notably breast cancer, it may be prudent to look to non dairy sources of calcium and vitamin D as protection against colon cancer.