Van Gool & Bridges
Appendixb
RISK FACTORS
Cholesterol
Over the last twenty years there has been a lot of research into the causes and effects
ofhigh cholesterol and its effect upon CVD. Most researchers would agree with the first
part of this research, which showed a strong correlation between cholesterol levels and
CHD. The second part of the research focuses on the causation side of the debate. The
debate has focused on what types of cholesterol cause CHD, and as yet there is no clear
agreement on this.
Cholesterol serves many essential processes in the human body. It is carried through
the body in plasma by lipoproteins and it synthesises various essential hormones to cell
membranes.
The majority of cholesterol is in the form of low-density lipoprotein (LDL) cholesterol.
A smaller proportion is in the form of high-density lipoprotein (HDL) and an even
smaller proportion by very low-density lipoprotein (VLDL). VLDL also serves a
mechanism for the transportation of triglycerides (Neil, 1996).
The Seven Coimtries Study (Keys, 1980) found a strong correlation between CHD and
mean serum cholesterol levels. This backed up by the Framingham Study’s (Kannel et
al, 1971) conclusion that there was a relationship between CHD and cholesterol.
The best evidence on the relationship between serum cholesterol levels and CHD comes
from the Multiple Risk Factor Intervention Trial (MRFIT) (Martin et al, 1986). This
study found that there was a continuous relationship between total serum cholesterol
levels and the rates of CHD across the full distribution of cholesterol levels. Thus, not
only should high cholesterol levels be of concern at a public health level, but at all
levels.
These studies, however, relate the total serum cholesterol level to CHD. More recently,
the focus has turned to the differing types of cholesterol and their differing effects upon
CHD. The point of contention is that some studies have found an inverse relationship
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Chere Project Report 11- November 1999