The evidence for this comes from three sources.

The graph shows the death rate per year based on blood (serum) levels of cholesterol. As the subjects become older the death rate inevitably increases, but more so in those with the lowest cholesterol levels.
The evangelists of the diet-cholesterol-heart hypothesis would not like this evidence, and it effectively has been suppressed - no-one seems to know about it. They might argue that the reason for the high death rate in those women with low
serum cholesterol is that they were dying of cancer, but this possibility was eliminated at the start of the study and during
the five-year follow-up during which 53 of the 92 women died, autopsy revealed
cancer to be the cause of death in only one.
Another interesting result was that at the onset of the study the average serum
cholesterol of women known to have coronary heart disease was 5.9mmol/L. The
corresponding cholesterol was higher at 6.3mmol/L in those who were not known
to have coronary heart disease. Again we see an advantage of a high cholesterol.

A second study of the elderly was undertaken in New Haven, Connecticut, a community-based study of 997 persons aged more than 70 years with follow-up for four years. The coronary heart disease mortality was once again that a higher level of serum cholesterol was associated with a lower death rate from coronary heart disease.
This graph shows the death rate but at a single point after four years. For men and women the lowest death was highest in those with the lowest cholesterol, less than 5.2, and lowest in those with the highest cholesterol, greater than 6.2.

In this graph we see the percentage surviving. It was clearly lowest in the quartile with the lowest cholesterol.
“A generally held belief is that
cholesterol concentrations should be kept low to lessen the risk of
cardiovascular disease. However, studies of the relation between serum
cholesterol and all-cause mortality in elderly people have shown contrasting
results….Only the group with a low cholesterol concentration had a significant
association with mortality…. We have been unable explain our results. These
data cast doubt on the scientific justification for lowering the cholesterol to
very low concentrations in elderly people.”
The conclusion appears to have been suppressed in the interest of those who benefit from the diet-heart-cholesterol hypothesis - pharmaceutical companies, food manufacturers and the academic departments which derive their funding from them.
There have been no studies published that show anything other than this detrimental effect of a low cholesterol level above the age of 60. To see the truth in younger age-groups you will need to wait for another post shortly.
The conclusion appears to have been suppressed in the interest of those who benefit from the diet-heart-cholesterol hypothesis - pharmaceutical companies, food manufacturers and the academic departments which derive their funding from them.
There have been no studies published that show anything other than this detrimental effect of a low cholesterol level above the age of 60. To see the truth in younger age-groups you will need to wait for another post shortly.