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Lactose Intolerance: Condition Information

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What is lactose intolerance?

People who are lactose intolerant have trouble digesting lactose, the natural sugar found in milk and milk products. They have this condition because their bodies do not make enough lactase. Lactase is an enzyme made in the small intestine. Lactase breaks down lactose into simpler forms of sugar, which are easily absorbed into the blood. Undigested lactose can lead to unpleasant digestive symptoms

People vary in their degree of lactose intolerance. Most people who are lactose intolerant are able to consume some lactose without symptoms. However, many people who think they are lactose intolerant avoid milk products and do not consume enough calcium and vitamin D,1 which are nutrients important to bone health. Getting enough calcium is especially important for children and teens, who are at the ages when bones grow the most.


  1. Suchy, F. J., Brannon, P. M., Carpenter, T. O., Fernandez, J. R., Gilsanz, V., Gould, J. B., et al. (2010). NIH consensus development conference statement: Lactose intolerance and health. NIH Consensus and State-of-the-Science Statements, 27(2), 1–27. PMID 20186234 [top]

Last Updated Date: 11/30/2012
Last Reviewed Date: 11/30/2012
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