Sunday, 29 May 2011

New, Very Bad Form of Cholesterol Discovered

Scientists have known for some time that several forms of cholesterol exist – HDL cholesterol (a good kind of cholesterol), LDL cholesterol (bad) and VLDL cholesterol (bad). Now a new type has been discovered  - MGmin-LDL (very bad).

Cholesterol is named according to the type of lipoprotein molecule that carries it through the blood. Cholesterol itself isn’t a bad molecule – in fact, it has vital functions in the body. For example, it’s a necessary part of cell membranes, forms part of the insulating covering around nerve fibers, is used to make the bile acids that prepare the fat that we eat for digestion and is converted into essential steroid molecules such as cortisol, aldosterone, and the reproductive hormones. Cholesterol only becomes a problem when too much collects in the blood.

HDL cholesterol is composed of cholesterol carried by high density lipoproteins. It’s considered to be a good form of blood cholesterol, since it travels away from cells and arteries to the liver, where the cholesterol is converted into other substances or eliminated from the body. 

LDL cholesterol, which consists of cholesterol attached to low density lipoprotein, delivers cholesterol to the cells. When there’s too much LDL cholesterol in the blood the cholesterol may collect in the lining of arteries, contributing to the formation of a deposit called plaque. Plaque can cause blood clots to develop and narrows the arteries, which can lead to a heart attack or stroke. VLDL cholesterol (very low density lipoprotein cholesterol) is converted into LDL cholesterol.

MGmin-LDL is formed when sugar is joined to LDL cholesterol molecules in a process called glycation. As a result of this process, the LDL cholesterol molecule changes its shape, becomes very sticky and is more likely to attach to artery walls. MGmin-LDL was discovered by researchers at the University of Warwick in Britain, who published their research in the science journal “Diabetes”. They found that the molecule is most common in people suffering from Type 2 diabetes and in older people, who have an increased risk of heart disease.

Metformin, a medication often given to diabetics to lower blood sugar, is known to also lower the risk of heart disease. The researchers believe that metformin blocks the transformation of LDL cholesterol into MGmin-LDL. The new understanding of how cholesterol can lead to health problems may lead to better treatments for diabetes and people at risk for heart disease.

The press release from the University of Warwick can be read here.