scientific theory can be thought of as a chain of evidence. Each piece of evidence links to the next in order to provide the required observational premise for the construction of a coherent and continuous path to the truth. The stronger the evidence provided, the stronger the chain becomes. However, as with a real chain, a theory is only as strong as its weakest link. Therefore contradictory evidence breaks the chain and provides sufficient doubt to suggest that the theoretical concept is flawed. If we continue along this line of reasoning, and apply it to the cholesterol theory of cardiovascular disease, we find that the chain of evidence is actually no such thing. The pretence that observational data shows a continual chain of evidence from dietary cholesterol to cardiovascular disease is evidently false to anyone who inspects the chain in detail. Picking up the chain shows it to be weak, discontinuous and tarnished, with some links being illusory.
One of the main problems with the cholesterol theory of cardiovascular disease is the absence of a link between dietary cholesterol intake and plasma cholesterol concentration. In fact the nutritional literature is replete with evidence refuting such an association. Admittedly, some studies do show an association between dietary cholesterol and plasma lipoprotein changes, but many of these studies have methodological flaws. For example, diets high in cholesterol and saturated fat are generally low in dietary fibre. Because dietary fibre is known to cause changes in plasma cholesterol levels, data from studies investigating cholesterol intakes that do not control for dietary fibre are flawed and their findings of questionable benefit. However, that some diets are high in cholesterol and saturated fat, contain very little fibre and yet still cause no cardiovascular disease is even more problematic for the cholesterol theory of cardiovascular disease.
The Maasai are a tribe of nomadic goat and sheep herders located in East Africa. They roam the scrub lands between Kenya and Tanzania and survive on a diet derived almost exclusively from their herds. This provides them with a diet of raw milk, raw meat and raw blood, which contains high concentrations of saturated fat and cholesterol. In addition, some of the villages within the tribe eat no plant foods and this provides them with virtually no dietary fibre or phytonutrients. Western diseases are absent from the historical medical records of such people, and this includes a complete absence of cardiovascular disease. While the unscientific practice of the ad hoc hypotheses have been the main defence against these findings, the Maasai remain to cholesterol theory of cardiovascular disease proponents what punctuated equilibrium is to Neo-Darwinists. In fact, the Maasai data is enough to burry the cholesterol theory of cardiovascular disease alone.
A more likely explanation for the reason that the Maasai do not develop cardiovascular disease is the fact that they do not eat refined carbohydrates or sugar. These foods are increasingly being linked to Western lifestyle disease, because they cause the development of insulin resistance in skeletal muscle and hepatic tissues. This results in the accumulation of lipids in the abdomen and this abdominal obesity causes the metabolic abnormalities associated with the metabolic syndrome. The metabolic syndrome is the likely cause of the modifications to plasma lipids associated with cardiovascular disease. Metabolic syndrome also causes an increase in free radical production and oxidative stress because macrophage influx to abdominal adipose tissue is present. This inhibits nitric oxide synthase, reduces nitric oxide synthesis and causes endothelial dysfunction. Therefore the chain of evidence linking sugar consumption to cardiovascular disease is far stronger than for dietary cholesterol.
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