Sugar in diet depletes good cholesterol
8 September 2014
Scientists at the University of Warwick have discovered that the
‘good’ form of cholesterol, HDL, is degraded by a sugar-derived
substance in the body.
The substance, methylglyoxal (MG), is formed from glucose
in the body. Supported by funding from the British Heart Foundation
(BHF) and published in the journal Nutrition and Diabetes,
the researchers discovered that MG causes HDL to lose the properties
which protect against heart disease.
MG damages the arginine (an amino acid) component in HDL at
a functionally important site on the molecule, causing it to become
unstable. HDL damaged by MG is rapidly cleared from the blood,
reducing its HDL content, or remains in plasma having lost its
beneficial function. Increased levels of MG are common in the
elderly and those with diabetes or kidney problems.
HDL cholesterol is called good because it removes excess
levels of LDL, the bad cholesterol, from the body. Low levels of HDL
are closely linked to heart disease. There are currently no drugs
that can reverse low levels of HDL, but the Warwick researchers
argue that discovering how MG damages HDL has provided new potential
strategies for reducing MG levels.
Lead researcher Dr Naila Rabbani, of the Warwick Medical School,
said, “MG damage to HDL is a new and likely important cause of low
and dysfunctional HDL, and could count for up to a 9% risk of heart
disease. By understanding how MG damages HDL we can now focus on
developing drugs that reduce the concentration of MG in the blood,
but it not only be drugs that can help. We call abnormally high
levels of MG ‘dicarbonyl stress’. This occurs in some diseases,
particularly diabetes, kidney dialysis, heart disease and obesity.
We need sufficient Glo1 to keep MG low and keep us in good health.
“We could now develop new food supplements that decrease MG by
increasing the amount of a protein called glyoxalase 1, or Glo 1,
which converts MG to harmless substances. This means that in future
we have both new drugs and new foods that can help prevent and
correct low HDL, all through the control of MG.”