Symptoms of lactose intolerance (belly pain, bloating, gas, and diarrhea) are very common, but not everyone who has symptoms can be diagnosed with the condition. Lactose intolerance is diagnosed by a breath hydrogen test ordered by your doctor.
Lactose intolerance occurs more often in First Nations peoples and people
of Asian, African, and South American descent than among people of European
descent. Experts believe that lactose intolerance is directly related to how
long ago a person's ancestors were introduced to dairy products.