Cholesterol & Heart Disease
How did scientists come to believe that high cholesterol was the cause of heart disease. Nikolai Anichkov, a leading Russian medical researcher, fed rabbits with purified cholesterol obtained from egg yolks dissolved in sunflower oil. In 1913 Anichkov published a definitive paper reporting his findings from the rabbit experiments. The level of cholesterol circulating in the rabbits’ blood quickly rose to four or five times the normal level and not surprisingly the rabbits began to develop fatty deposits in their coronary arteries similar to those found in humans with advanced atherosclerosis. The deposits in rabbits also appeared in other places in their bodies.
To many people that might seem to have been a pointless experiment. After all, rabbits eat grass not cholesterol and all the cholesterol in their bodies is manufactured in their cells from the grass they eat, the air they breathe and the water they drink. The experiments he carried out in grass-eating rabbits could not be reproduced in other animals such as dogs or rodents. All of these species, like humans, can ingest saturated fats and cholesterol without causing a significant change in the level of cholesterol circulating in their blood. In fact, only about 20% of the circulating cholesterol in man is obtained directly from food. The remaining 80% is synthesised in the cells of the body from biochemicals obtained from the breakdown of foods which do not contain cholesterol and irrespective of the amount of fat consumed, the blood level of cholesterol remains fairly constant in a particular individual. Nevertheless, Anichkov was confident that it was the high level of cholesterol circulating in the blood which ended up in the walls of the arteries. He continued his work with rabbits and ultimately satisfied himself that there was a clear relationship between the level of cholesterol circulating in the blood and the debris in the artery wall. One cannot disagree with his conclusion except to say that the deposition of cholesterol in the arteries did not occur unless the cholesterol circulating in the rabbits’ blood was artificially increased to four or five times the normal level which could only occur in abnormal circumstances. Anichkov concluded his 1913 report with the unwarranted observation that the level of circulating cholesterol in the blood of human beings was a key factor in the development of atherosclerosis and therefore lowering the amount of circulating cholesterol would reduce the incidence of heart attacks. Without much thought, Anichkov and his followers translated an illogical experiment carried out on rabbits to the human domain in the firm belief that what happened in the grass-eating rabbits would be equally true for humans. This came to be known as the ‘lipid hypothesis’. Later it would be the basis of a ‘scientific’ belief which sent many millions of individuals to an early grave. Michael Brown and Joseph Goldstein, the two researchers who won the Nobel Prize for their work on statins claimed that the rabbit study was the basis for their belief that high cholesterol caused heart disease.