Lactose intolerance is the inability to metabolize lactose, because of a lack of the required enzyme lactase in the digestive system. It is estimated that 75% of adults worldwide show some decrease in lactase activity during adulthood.[1] The frequency of decreased lactase activity ranges from as little as 5% in northern Europe, up to 71% for Sicily, to more than 90% in some African and Asian countries.
Lactose intolerance is not usually an all-or-nothing condition: the reduction in lactase production—and hence, the amount of lactose that can be tolerated—varies from person to person. Since lactose intolerance poses no further threat to a person’s health, managing the condition consists of minimizing the occurrence and severity of symptoms. Berdanier and Hargrove recognise four general principles: avoidance of dietary lactose, substitution to maintain nutrient intake, regulation of calcium intake, and use of enzyme substitute.
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