In fact, the inability to digest lactose into adulthood is the norm. The ability to digest lactose is the exception - resulting from a mutation on a gene on chromosome 2. The normal, non-mutated condition for human populations is the gradual loss of production of the enzyme, lactase, that splits the milk sugar, lactose, into its absorbable components: glucose and galactose. This loss is about 90% complete by age 4.1
Some populations have retained this mutation, allowing them to consume dairy products without the gas, bloating, cramping, and diarrhea typical of lactose intolerance:
"The frequency of lactose maldigestion varies widely among populations but is high in nearly all but those of European origin."Lactose intolerance worldwide:
In North American adults lactose maldigestion is found in approximately:
In Africa, Asia, and Latin America prevalence rates range from 15-100% depending on the population studied"
- 79% of Native Americans
- 75% of blacks
- 51% of Hispanics
- 21% of Caucasians
- The Acceptability Of Milk And Milk Products In Populations With A High Prevalence Of Lactose Intolerance, American Journal of Clinical Nutrition, 1988
I've read that, taken together, about 75% of the world's population, and about 25% of the US population, can't effectively digest milk sugar. Our poll seems to bear this out:
Results of our milk poll:
Do you eat or drink milk (raw, skim, powdered, fermented, cheese, butter, cream, etc.)?