Cholesterol, a natural body constituent in humans has attracted highest attention during the last 3 decades mainly because of its established linkage to heart related diseases. Man's knowledge about cholesterol has progressed from establishing a higher limit for total cholesterol a few years ago to the optimum levels for High Density Lipoprotein Cholesterol (HDL-C), Low Density Lipoprotein Cholesterol (LDL-C), Very Low Density Lipoprotein Cholesterol (VLDL), total Cholesterol to HDL-C ratio etc that is desirable to maintain cardiac health. HDL-C is one of the five groups of lipoproteins designed to transport cholesterol and triglycerides within the predominantly water based blood stream and is considered the most significant in protecting heart by carrying cholesterol away from atheroma within arteries and transport it back to the liver for excretion or re-utilization.
HDL-C promoted as good cholesterol amongst the layman is supposed to protect humans against cardiovascular diseases while LDL-C and VLDL-C are considered villains as far as heart health is concerned. According to the present understanding HDL-C at levels below 40 mg/dL in blood can increase the risk of coronary vascular disease (CVD) significantly amongst normal population. HDL-C has also a role in delivering cholesterol to adrenals, ovaries and testes for the synthesis of steroid hormones. HDL-C carries many lipid and protein species which even at low concentrations are biologically very active. HDL-C and its protein and lipid constituents are also believed to be helpful for inhibiting oxidation at cellular level, inflammation, activation of the endothelium, coagulation and platelet aggregation. The common perception at present is that humans should have optimum HDL-C levels about 60 mg/dL in blood or higher but not less than 40 mg/dL for reducing the risk of CVD.
Amongst the means of increasing HDL-C in the blood include aerobic exercises for 20-30 min, losing weight to desired BMI, cessation of smoking and alcohol consumption, avoiding saturated and trans fats in the diet, consumption of mono saturated fatty acids, increased intake of soluble fiber in the diet by including oats, fruits and vegetable, legumes etc and omega-3 fatty acids from fish. As a general guideline restricting the intake of calories from fat through the diet to a broad range of 25 to 35 % is considered a healthy practice. The value for the ratio of total cholesterol to HDL-C should not be more than 5:1.5 for a normal healthy adult and obviously higher the HDL-C or lower the total cholesterol better would be the ratio.
In a recent startling study it was brought out that high HDL-C need not be a heart health indicator amongst some female population, though these findings were confined to Danish women. On the contrary high HDL-C could be a cause for ischemic heart disease causing chest pain, heart attack and even death. This group displayed high levels of C-reactive proteins (CRP) which is known as an inflammation marker. Genetic changes that can result in deficiency of the vital enzyme Cholesteryl Ester transfer Protein (CETP) involved in transfer of cholesteryl ester from HDL-C to triglyceride rich lipoproteins can lead to accumulation of cholesterol in the arteries causing ischemic heart conditions. Though the study was confined to Danish women, a wider investigation across the world only can reveal what percentage of women have this genetic deficiency. The blind recommendation about HDL-C requires moderation in the light of the above findings.