Lactose intolerance is an impaired ability to digest lactose, a naturally occurring sugar in milk and other dairy foods. Lactose intolerance is uncomfortable but it's not dangerous and it's not an allergy. Don't confuse lactose intolerance with a cow milk allergy, which can cause a life-threatening allergic reaction when a tiny amount of milk is consumed. Most people with lactose intolerance can eat small amounts of dairy products if they're careful.
Causes
Normally lactose is digested by the enzyme lactase, which is produced in the lining of the small intestine. Lactose intolerance is caused by a deficiency of lactase, which allows undigested lactose to pass into the large intestine, where it causes digestive complaints. Not everyone with a lactase deficiency develops the symptoms of lactose intolerance. Some people develop lactose intolerance in adolescence or adulthood because their body produces less of the enzyme as they age. Others develop lactose intolerance because of an injury to the small intestine from severe diarrhea, celiac disease, Crohn's disease or cancer treatment. This can happen at any age but is most common in babies. In rare cases, a baby can be born with a complete absence of lactase due to a genetic condition and is lactose intolerant from birth. These babies cannot tolerate their mother's milk and require special lactose-free formula.
Symptoms
People with lactose intolerance usually develop symptoms 30 minutes to two hours after consuming a dairy product. The severity of the symptoms varies depending on how much of the dairy food was eaten and how much the person can tolerate. Symptoms include stomach pain and bloating, gas, diarrhea and nausea.
Risk Factors
The risk of lactose intolerance increases as you age. Lactose intolerance is more common in some populations, including people of African, Hispanic, Native American and Asian descent. People of northern European descent are least likely to develop lactose intolerance. Premature infants are also more likely to develop lactose intolerance because the baby's lactase levels are not built up until late in the pregnancy.
Treatment
Lactose intolerance cannot be cured but it can be managed with dietary changes. How much lactose a person can tolerate varies from patient to patient, so you will have to experiment to see what works for you. Some people with lactose intolerance can drink a glass of milk without symptoms, while others cannot tolerate milk at all. Others can eat yogurt and hard cheeses like cheddar, which have lower levels of lactose. You may find that you can reduce your symptoms by eating dairy products with meals or by slowly introducing small amounts of dairy to build up your tolerance. There are also lactose-free milk and dairy products available. You may also want to try taking lactase enzyme drops or tablets when you eat dairy products. Lactase is available over the counter.
