Insulin resistance is thought to lead to the development of the metabolic syndrome, a condition characterised by serious metabolic dysfunction. One such associated abnormality is dyslipidaemia, which usually manifests itself as raised plasma levels of very low density lipoprotein (VLDL) and low density lipoprotein (LDL), in addition to lowered levels of high density lipoprotein (HDL). The development of metabolic syndrome is a risk factor for type 2 diabetes and cardiovascular disease, both of which are characterised by the same dyslipidaemia. While mainstream medical establishment has attempted to force down this dyslipidaemia as if it was the cause of cardiovascular disease, nutritional research has shown that control of the raised plasma lipids is possible using food, which address the underlying cause of the problem. In particular, fish oils have been shown to be particularly effective at lowering VLDL, which represent the fasting level of triglycerides in the plasma.
Fish oils are most effective at treating dyslipidaemia in those with elevated levels, as might occur in subjects with type 2 diabetes. In a meta-analysis of relevant studies1, researchers attempted to quantify the effectiveness of fish oil supplements on the plasma lipoprotein concentrations in type 2 diabetics. Analysis of 18 trails with 823 subjects were included that had a mean length of 12 weeks and administered doses from 3 to 18 grams per day. Fish oil supplements were able to significantly lower plasma VLDL (triglycerides) by an average of 0.56 mmol/L, and also modestly but significantly raise LDL by 0.21 mmol/L. However, fish oil supplements had no effect on total cholesterol and did not significantly affect HDL. The authors noted that the triglyceride lowering effects were most significant in those studies using subjects with the most elevated levels and with the highest concentrations.
Fish oils appear therefore to be an effective supplement for lowering plasma concentrations of VLDL. Fish oils can lower plasma VLDL because they decrease secretion of triglycerides from the liver. The increase in LDL is interesting but has been previously reported in the literature following fish oil supplements2. It is thought that fish oil supplements decrease the uptake and catabolism of intermediate density lipoproteins (IDL) instead causing production of LDL through cholesterol uptake. As the length of time the LDL particles stay in the plasma does not change, the result is an increase in LDL particle number in the plasma. However, LDL is made up of both small dense particles and large buoyant particles, with only the former type increasing risk of cardiovascular disease. Fish oils may increase only the large buoyant particles of LDL and the increase in concentration may not signify a detrimental change.
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