Is it possible to develop lactose intolerance, or other types of food intolerance, as you get older? I now get an upset stomach from dairy.

Lactose intolerance is the inability to digest lactose, a sugar found in milk and milk products. Lactose intolerance is caused by a deficiency of the enzyme lactase, which is produced by the cells lining our small intestine.

Although many people have adverse reactions to certain foods, most are caused by food intolerance and not a food allergy. Milk allergy is a reaction by the body's immune system to one or more milk proteins and can be life threatening when just a small amount of milk or milk product is consumed.

Milk allergy most commonly appears very early in childhood, while lactose intolerance occurs more often in adulthood. Primary lactase deficiency develops over time. Our bodies begin to produce less lactase starting in childhood. Most children who have lactase deficiency don't experience symptoms of lactose intolerance until late adolescence or adulthood.

People with lactose intolerance may feel uncomfortable 30 minutes to two hours after consuming milk and milk products. Symptoms ranging from mild to severe can include abdominal pain, abdominal bloating, gas, diarrhea and nausea.

The symptoms of lactose intolerance can be managed with dietary changes. Lactose-free and lactose-reduced milk and milk products are available at most supermarkets. Foods lower in lactose such as hard cheeses and yogurt can sometimes be consumed without side effects. Soymilk and other soy products free of lactose may be consumed as well.

People who still experience symptoms after dietary changes can take over-the-counter lactase enzyme drops or tablets that may make lactose-containing foods more tolerable for people with lactose intolerance.