Several obese people walk down a street in Sydney (Australia) .ASSOCIATED PRESS
All that glitters is never gold. Neither the lives of influencers on Instagram nor the bonanzas of high-density lipoproteins that flow through the tissues of the human body. These particles, known as HDL, are the transporters of cholesterol, a fatty substance necessary for life , although dangerous if it accumulates excessively in the arteries. HDL, however, has a very good reputation and, in fact, is also called good cholesterol because, unlike low-density lipoproteins (LDL or bad cholesterol ), they capture this fatty substance deposited in the arteries and transfer it to the liver, where it is eliminated. Thus, having high HDL was a cardioprotective sign, while elevated LDL levels implied an increased risk of heart problems – these lipoproteins carry cholesterol to cells, but are unable to transport the excess to the liver for elimination. However, an investigation by the Hospital del Mar in Barcelona has shaken the benefits of HDL and has concluded that good cholesterol is not so good . Or at least, not all: only a subset, small HDL particles, are associated with a decrease in cardiovascular risk. Large HDL particles, no.
Raising levels of good cholesterol does not reduce the risk of heart attack Does "good cholesterol" really deserve this label?
“We had many studies that showed us the risk of coronary heart disease: high levels of HDL decrease the risk and high levels of LDL increase it. With regard to prevention, in fact, we have several families of drugs to lower LDL and, by lowering these levels, the risk of cardiovascular disease is reduced ”, explains the researcher at the Hospital del Mar-IMIM, Roberto Elosua. The key is that LDL does not reach the liver. "It is not capable of attaching itself to liver receptors, it does not fit in and it cannot release cholesterol in the liver to eliminate it," the expert specifies. Cholesterol is deposited on the walls of the arteries and can cause atherosclerosis: it accumulates in the blood vessel and forms a kind of plaques that narrow the arteries and restrict the passage of blood.
For researchers, the "Holy Grail", as Elosua calls it, it was to find a drug that increased the levels of good cholesterol. “In the 2000s, drugs were made that almost doubled HDL levels, but they were found not to reduce the risk of cardiovascular disease, but to actually increase it . So their use was not authorized and they did not reach pharmacies, ”says Elosua. But the failure of these drugs was the starting point for the Hospital del Mar researchers: they began to question whether there really was a causal relationship between HDL levels and coronary heart disease.
“And we went to genetics to analyze whether this relationship it was causal or not. We know some genetic characteristics, changes in the position of some letter in the genome sequence, which makes some people have more HDL. And we think: if I have genetic characteristics that make me have more HDL than you, I should also have more cardiovascular protection, "he explains. But this premise was not fulfilled: "HDL did not cause a decrease in the risk of heart attack."
What they did discover, however, is that the key was in the subgroups of HDL, that there are smaller particles or more particles big. The experts found that those genetic characteristics linked to the creation of large particles of good cholesterol were not so favorable. In fact, they were directly related to a higher risk of heart attack. However, the genetic characteristics associated with small particles of good cholesterol were associated with a lower risk of heart attack. "The small HDL particles are more functional in the reverse transport of cholesterol, which is the transfer of cholesterol to the liver to be eliminated through the feces", summarizes Elosua.
This finding does not yet have a visible impact on clinical practice, but it does open a window of opportunity. To begin with, to research new drugs. " If we could use drugs to modulate the activity of these genes associated with the creation of small HDL particles , we could increase their levels in the body," says Elosua, and increase cardiovascular protection. The researcher, who has published his study in the journal Metabolism Clinical and Experimental , also does not rule out that, in traditional blood tests, the evaluation of HDL broken down according to the subgroup of particles is routinely implemented to better refine the real cardiovascular risk.
For now, and in the absence of drugs and a more exhaustive control of true good cholesterol, Elosua reveals two elements that play in favor of increasing levels of good and good cholesterol : "the Mediterranean diet and physical exercise ". That does not fail.
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newsletter Source: Elpais