Our intestines produce lactase, an enzyme required for the proper digestion of lactose. Some people, especially of African-American or Latino heritage, develop lactose intolerance because they don't produce adequate amounts of lactase.
Symptoms of lactose intolerance can include abdominal cramping, gas and/or diarrhea. With mild intolerance, the concentration of lactase may be insufficient, but still present, so dairy products that are lowest in fat are easier to digest.
Calcium and vitamin D-enriched soy milk, almond milk, hemp milk and rice milk can be good alternatives when all dairy products need to be avoided. They contain much of the nutrients in regular milk but none of the lactose. H-E-B MooTopia® milk is also a great choice because it also has reduced lactose. Other lactose-free milk options have the lactase enzyme added to aid in the digestion process.