Lactase is an enzyme located in the mammalian small intestine that breaks down lactose into sugars, glucose and galactose. It is a necessary enzyme in order to digest lactose, a milk sugar, which cannot be absorbed directly.
Lactose is a sugar found only in mammalian milk
According to the article, there is high production at birth and then lactase production starts decreasing in adulthood. However, through recent studies, it is shown that there is a high variation in lactase production among individuals and population which could be divided into a group with continuous high lactase production and a group with declining lactase production.
The authors are point out that the most commonly used term, lactose tolerance/intolerance are reflecting the gastrointestinal symptoms after taking lactose. However, people with high lactase production can show the symptoms of intolerance and people with low lactase production show no symptoms at all. Therefore, it is preferred to use the term lactase persistence/non-persistence, lactase restriction and etc. Also the authors argues that the term lactose persistence/non-persistence doesn’t necessarily imply too high or low lactase activity.
After learning that the gastrointestinal symptoms and lactose intolerance doesn’t necessarily correlate, I think it would be more accurate to classify with lactase persistence/non-persistence. For example, I can tolerate lactose but I can show those symptoms. So does that make me lactose intolerant? 1. What populations exhibit adult lactase persistence?
According to the article, there are four most common types of lactase haplotype: A, B, C, and U. Type A is mostly associated with lactase persistence and it can be found in northern Europeans mostly. The article lists groups of population with high rates of lactase persistence: northern Europeans; South Asians; herding populations of the Middle East, Arabian Peninsula, and sub-Saharan Africa; and descendants of these populations.
The author mentions that the population that lives at high latitude which lacks UV light had lactase persistence. Vitamin D becomes synthesized in skin when there is UV light and of course lack UV lights reduces Vitamin D being synthesized; presence of lactose in small intestine increase the absorption of calcium and for this reason, that population would have selected lactase persistence.
Dairy-dependent population would have been healthier and well-nutritioned because milk contains numerous important nutrition. So having long histories of dairying possibly could have increased lactase persistence among population.
. Another hypotheses suggests that lactase impesistence is selected as a defense mechanism against Malaria which is one of the deadly disease. The author explains that milk contains high level of the riboflavin, and malarial parasites needs riboflavin to multiply in blood. Therefore the lack of riboflavin would prohibit the malarial parasites from multiplying in blood.
Everyone knows the advertisement “got milk?” and this advertisement definitely had positive impact on the consumption of milk. USDA is an organization that provide guidelines to the U.S. citizens and people are sensitive to the information that USDA provides because people have high trust in them. Therefore, USDA promoting dairy consumption through food pyramids, or any form of recommendation had significant impact on the dairy consumption of the U.S. citizens. Also, having NDC members as part of a project definitely led to a biased decision or recommendation for the U,S, citizen.
I personally did not know that high percentage of minority groups are lactase impersistent and it was pretty shocking. Considering the minority groups are dramatically increasing in the U.S. population, USDA continuing with the current recommendation which involves dairy(or milk) consumption shows the ignorance towards the minority groups which are part of the U.S. citizens as well and therefore, it is conflicting with its purpose.