A study led by Roberto Elosua, a lecturer in the Faculty of Medicine, shows that not all good cholesterol is healthy

HDL cholesterol (high-density lipoprotein cholesterol), known as "good cholesterol", is associated with a lower risk of developing cardiovascular disease as it transports cholesterol deposited in the arteries to the liver for elimination. However, LDL cholesterol (low-density lipoprotein cholesterol), known or "bad cholesterol", causes cholesterol to build up in the arteries and increases cardiovascular risk. Although drugs that lower levels of bad cholesterol reduce cardiovascular risk, those that raise good cholesterol have not been shown to be effective in reducing the risk of cardiovascular disease. This paradox has called the relationship between good cholesterol and cardiovascular risk into question, and researchers are currently studying the characteristics of these particles of HDL, or good cholesterol.

The study High-density lipoprotein characteristics and coronary artery disease: a Mendelian randomization study led by the Hospital del Mar Medical Research Institute (IMIM), in which the lead researcher is Dr Roberto Elosua, a lecturer at the Faculty of Medicine of the University of Vic - Central University of Catalonia (UVIC-UCC), has shown that not all good cholesterol is healthy. Researchers at the Cardiovascular Diseases Biomedical Research Centre (CIBERCV), the Obesity and Nutrition Biomedical Research Centre (CIBEROBN) and the Epidemiology and Public Health Biomedical Research Centre (CIBERESP) as well as the Hospital Clínic-August Pi i Sunyer Biomedical Research Institute (IDIBAPS), the Bellvitge Biomedical Research Institute (IDIBELL),  the Research Institute of the Hospital de la Santa Cruz y Sant Pau and the Hospital Clínico Universitario in Zaragoza co-authored the study, which has been published in the journal Clinical and Experimental Metabolism.

The size of good cholesterol particles is crucial

The researchers analysed genetic traits that determine the size of good cholesterol particles, and then studied their relationship to the risk of experiencing a myocardial infarction. They came to the conclusion that the genetic traits associated with the generation of large good cholesterol particles were directly related to a higher risk of heart attack, while the genetic traits associated with small good cholesterol particles were related to a lower risk of a heart attack. "There is a positive causal relationship between the size of HDL cholesterol particles and the risk of a heart attack, so we must be able to increase good cholesterol levels in the blood, but always as small particles," said the study’s lead researcher, Dr Robert Elosua, a researcher at the Hospital del Mar-IMIM, CIBERCV and UVic-UCC.

Good cholesterol particles are more effective at transferring cholesterol to the liver for elimination. "If we need to do anything with HDL, that is increasing the number of small particles, which are those that do the job of removing cholesterol properly - they are those that move it to the liver for elimination and don't allow it to build up in the arteries and cause cardiovascular disease," says Dr Álvaro Hernáez, researcher at IDIBAPS and CIBEROBN.

There are currently no drugs that increase good cholesterol levels and reduce the risk of developing cardiovascular disease. "This study highlights new and potential therapeutic targets in the field of cardiovascular disease, such as various genes related to the qualitative aspects of HDL particles, which may contribute to preventing cardiovascular problems," concludes Dr Albert Prats, a researcher in the Epidemiology and Cardiovascular Genetics Research Group at the Hospital del Mar-IMIM, and the first author of the study.