1.3.14 Analyse and interpret data on the possible significance for health of blood cholesterol levels and levels of high-density lipoproteins (HDLs) and low-density lipoproteins (LDLs). Describe the evidence for a causal relationship between blood cholesterol levels (total cholesterol and LDL cholesterol) and CVD.

Studies show a strong correlation between high intake of saturated fats and high blood cholesterol; cholesterol helps to form plaque (this is a casual link). 

LDL is formed from saturated fats, protein, and cholesterol, it binds to cell surface receptors, which can become saturated leaving the LDLs in the blood. Therefore LDL is associated with the formation of atherosclerosis and should be maintained at a low level. 

HDL is formed from unsaturated fats, proteins, and cholesterol, it transports cholesterol from body tissue to liver where it is broken down. Therefore HDL reduces blood cholesterol level; discourages atherosclerosis and should be maintained at a high level.