You make a good point, of course, about digestion, but this would then apply those individuals, and not the general population.
I disagree, When the scope is not America alone. It would apply to the general population. And as I said before many people do not know they can not properly digest milk. I believe the actual number in America alone who can not properly digest milk to be much higher then it is thought to be.
Here are a few exerts to back up my claim...
according to Harvard,
90 percent of Asians, 70 percent of blacks and Native Americans, and 50 percent of Hispanics are lactose-intolerant.
Overall, about 75 percent of the world's population, including 25 percent of those in the U.S., lose their lactase enzymes after weaning.
Hertzler SR, Huynh BCL, Savaiano DA. How much lactose is low lactose? J Am Dietetic Asso 1996;96:243-6.
.
Approximately 70 percent of African Americans, 90 percent of Asian Americans, 53 percent of Mexican Americans, and 74 percent of Native Americans were lactose intolerant.
1. Cuatrecasas P, Lockwood DH, Caldwell JR. Lactase deficiency in the adult: a common occurrence. Lancet 1965;1:14-8.
2. Huang SS, Bayless TM. Milk and lactose intolerance in healthy Orientals. Science 1968;160:83-4.
3. Woteki CE, Weser E, Young EA. Lactose malabsorption in Mexican-American adults. Am J Clin Nutr 1977;30:470-5.
4. Newcomer AD, Gordon H, Thomas PJ, McGill DG. Family studies of lactase deficiency in the American Indian. Gastroenterology 1977;73:985-8.
Studies showed that a substantial reduction in lactase activity is also common among those whose ancestry is African, Asian, Native American, Arab, Jewish, Hispanic, Italian, or Greek.
Mishkin S. Dairy sensitivity, lactose malabsorption, and elimination diets in inflammatory bowel disease. Am J Clin Nutr 1997;65:564-7.