Question

pernicious anemia
in the 1920s, george minot was searching for a cure for pernicious anemia, a then - fatal disease characterized by the bodys inability to produce enough red blood cells. minot began experimenting with feeding large amounts of beef liver to his patients—up to half a pound per day. incredibly, the diet produced marked improvements. why the medical miracle? as revealed by later research, liver contains high levels of vitamin b₁₂, which is essential for the production of red blood cells. people with pernicious anemia lack a glycoprotein called intrinsic factor, which helps the body absorb vitamin b₁₂ in the small intestine. as a result, their red blood cell numbers drop. because minots patients could absorb only a tiny percentage of the vitamin b₁₂ in their food, they had to ingest large amounts of liver in order to survive. today, people with pernicious anemia are prescribed b₁₂ injections so that they no longer have to rely on the \liver cure.\
what is the main, or central, idea of the passage?
minots pernicious anemia patients had to eat significant quantities of liver in order to see improvements, since b₁₂ was difficult for them to absorb.
the lack of intrinsic factor leads to an inability to absorb vitamin b₁₂.
minots liver cure experiment led to the discovery that a condition called pernicious anemia involves the inability to absorb vitamin b₁₂.

Explanation:

The passage details Minot's experiment with liver - feeding for pernicious anemia patients, the role of vitamin B₁₂ and intrinsic factor, and modern treatment. The main focus is on Minot's experiment and the related discovery about pernicious anemia and vitamin B₁₂ absorption.

Answer:

Minot's liver cure experiment led to the discovery that a condition called pernicious anemia involves the inability to absorb vitamin B₁₂.