Lactose digestion and maldigestion: implications for dietary habits in developing countries

Milk is an important source of high quality protein, energy, calcium, potassium, phosphorus and riboflavin. It also has good functional properties and a highly acceptable taste, making milk a good alternative for the nutrition of children and for food programmes in developing countries. However, in some instances it has been advocated that milk or milk based products might not be appropriate for nutritional support, given the high prevalence of lactose intolerance among populations in those countries. After reviewing studies in different regions of the world it is concluded that: 1. Prevalence of lactose maldigestion in children and adults is significantly reduced, to less than half in most studies, when assessed with a dose of milk similar to that normally taken in the diet, as distinct from a large dose of lactose used in the lactose tolerance test. 2. Lactose intolerance as a result of consuming a glass of milk occurs only in a small proportion (about 30% in most studies) of lactose maldigesters. Even this small group can ingest smaller amounts of milk without adverse symptoms and there is good evidence that colonic metabolism in these people adapts to the presence of lactose to reduce or eliminate adverse symptoms. 3. Lactose maldigestion and intolerance in children in developing countries is more likely to exist in association with gastrointestinal damage associated with diarrhoea, malnutrition and/or infection. 4. There is no evidence to support a reduction or elimination of milk intake for people in developing countries because of lactose maldigestion or intolerance.