Clipping of news on Brazilian Culture, Law and Citizenship
01/18/2013
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HDL even at high doses may have the effect reduced as a result of oxidation
Not as good cholesterol. A molecule of HDL Latinstock
Berlin-New studies put down the theory that high rates of so-called good cholesterol (HDL, high density lipoprotein) are sufficient to protect the heart from excess bad cholesterol (LDL, low-density lipoprotein). Two surveys, conducted in centers of heart disease at the universities of Zurich, Switzerland, and Leipzig, Germany, shows that HDL can lose its protective effect as a result of oxidation.
The researcher Volker Adams, head of the Laboratory of Cardiac Heart Center, University of Leipzig, Germany, found that the protective effect of HDL is impaired by oxidation. HDL removes cholesterol from arteries and carries it back to the liver for excretion or re-utilization. When it is oxidized, however, fails to fulfill this function. According to the expert, vitamin B3 improves the protective function of HDL, but the most effective is the practice of daily exercise.
- After 30 minutes of walking daily laboratory tests indicate an improvement in the performance of good cholesterol - explains Adams.
Tests with a group of 24 people (eight healthy, eight with mild heart problems and eight in serious condition) showed that after three months of regular exercise (at least 30 minutes of walking per day), there was a reduction of 30 % oxidation of the HDL.
- Up to eight patients with severe heart failure showed improvement - says Adams, who currently pursues the study to find out if regular exercise improves the performance of HDL in their ability to transport cholesterol from the arteries to the liver.
Protective effect in the body
According to him, HDL increases the production of nitric oxide (NO), the transport of cholesterol from arteries to the liver where it is decomposed and moved into the intestine. NO reduces the pressure in the blood vessels, and thus have a protective effect.
Ten years ago an American study had shown a suspicion that a higher rate of HDL (over 50 mg / dl) in the blood does not always mean more protection against cardiovascular disease. Five years later, the team of expert Ulf Landmesser, University of Zurich, Switzerland, began to decipher the riddle of the disorder function of HDL and, in 2011, the initial findings were published in the journal "The Journal of Clinical Investigation" .
- Our first conclusion was that people suffering from arterial disease had a functional disorder, although the rates of good HDL. Apo A-1, most important protein of HDL, showed error function as a result of increased apo-3 - says Landmesser, who coordinates a survey of 500 people with cardiovascular problems about blocking the protective function of HDL.
The innovation shown by the new studies is that HDL can not always protect the heart. Therefore, attempts to improve drug cholesterol based on increasing HDL failed. For nearly six years, Pfizer discontinued a study with a substance (torcetrapib), capable of increasing HDL, which would have caused an increase in cases of death instead of the desired effect of reducing fatalities. Eighty-two of the fifteen thousand patients in the study died. Another attempt was made by the Swiss laboratory Hoffmann-La-Roche with a like substance, dalcetrapib, which did not show the desired effect. The study ended in May last year.
General imbalance in metabolism
For Landmesser, the loss process positive function of HDL is complicated because it involves several factors. Besides the composition of proteins, which would cause the imbalance free radicals attack HDL, he found that the oxidation process, which takes its HDL protective capacity, also occurs as a result of a disorder of an enzyme lipoprotein associated, called paraoxonase. The expert found that people suffering from type 2 diabetes had a higher rate of imbalance of paraoxonase, which he explains as the result of a general imbalance of metabolism. But healthy people could also have the same disorder.
For years the theory of the good cholesterol HDL suggests that a rate above 50 mg / dl would be able gradually to reduce the effect of bad LDL, it should be up to 160 mg / dl, and the overall rate recommended for a healthy life something around 200 mg / dl.
- Even today it is the rule that the LDL too high and too low HDL have the effect time bomb that can explode as heart attack or stroke - Landmesser says.
According to the Austrian physician Hans Holdhaus sports, cardiovascular diseases attack more today than in the past because of the high degree of sedentary lifestyle of modern life.
- In the Stone Age, a person walking on average 19 kilometers per day. Today the average is 800 meters and this is reflected in health statistics - concludes Holdhaus, which advocates a return to the origins of man, at least as regards the movements.
Source: The Globe - Online
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This article was translated by an automatic translation system, and was therefore not reviewed by people.