Translation: This person doesn’t make enough of the enzyme needed to digest lactose, the sugar in milk. Consuming dairy causes gastrointestinal discomfort (e.g., bloating, diarrhea) within 30 minutes to two hours. Odds: 1 in 6 people. According to the National Institutes of Health (NIH), up to 50 million Americans are lactose-intolerant. Also consider: Using lactose-free milk. People with lactose intolerance can safely digest the proteins in milk, just not the sugars. Some can tolerate aged cheeses and yogurts with live active cultures. Learn more: digestive.niddk.nih.gov/ddiseases/pubs/lactoseintolerance/.