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What’s Good About Cholesterol

You just had your annual physical exam, and you proudly present your laboratory results to your physician. Everything seems well; you’re sure your physician will be pleased with you. Why, all your results are normal, and one, which says HDL cholesterol in your lipid profile, is even low! But after showing your results, your physician tells you that you should do something about your HDL. Huh? But it’s low so that’s supposed to be good, right? What is HDL cholesterol anyway? Aren’t all cholesterols the same?

The answer to that is NO, not all cholesterols are the same. There are ‘bad’ cholesterols, which are the LDL and triglycerides, but there is also ‘good’ cholesterol, which is the HDL. While LDL and triglycerides act in a separate but similar manner to clog your arteries by forming and depositing plaques in the inner walls of your arteries, HDL acts to ‘undo’ these bad effects by cleaning up and moving the unhealthy fats in your bloodstream out of your body. HDL does this by a process called ‘reverse cholesterol transport’; it helps extract excess fats deposited in the blood vessel walls and transports them back to the liver for elimination out of the body. Consequently, HDL helps keep your blood vessels dilated, therefore promoting better blood flow.

It also has antioxidant and anti-inflammatory functions that help reduce blood vessel injury. Since HDL is protective against development and progression of heart disease, a higher HDL value is desired especially for people with other cardiovascular risks. Studies have shown that for every 1 mg/dL increase in HDL, the risk for developing cardiovascular disease decreases by 2-3 percent. Conversely, the lower the HDL, the higher the cardiovascular risk.

As shown in the Framingham Heart Study, this linear relationship between HDL and cardiovascular risk is apparent even in patients whose bad cholesterol is already low or normal. This means that you are still at increased risk for heart attack or stroke if your HDL is low, even if your LDL or bad cholesterol is already controlled. So how do you know if you have low HDL cho-lesterol? According to the National Cholesterol Education Program-Adult Treatment Panel III (NCEP-ATP III), a low HDL cholesterol is defined as a level less than 40 mg/dL. For women, the American Heart Association considers HDL cholesterol to be low if it is below 50 mg/dL.

HDL cholesterol and diabetes
Diabetics should be extremely vigilant about keeping their cholesterol controlled. This is so because of a condition called diabetic dyslipidemia, wherein diabetes tends to lower the good cholesterol and increase the bad cholesterol, therefore increasing the risk for premature heart disease and atherosclerosis (clogging of arteries by accumulated fat).

How does this happen? Studies show a link between insulin resistance, a precursor to type 2 diabetes, and diabetic dyslipidemia. Because of insulin resistance, the pancreas of a diabetic patient needs to secrete more insulin to handle the sugar load from food intake and enable sugar to enter the vital organs to be utilized as nutrient. High levels of insulin in the blood then tend to lower the HDL cholesterol and increase the LDL cholesterol. Sadly, the cholesterol changes are inde-pendent of blood sugar control in Type 2 diabetics. This means that the dyslipidemia tends to persist even if blood sugars are well-controlled.

Post-menopausal women also tend to have lower good cholesterol. This is because the loss of estrogen after menopause also drops the blood levels of good cholesterol.

How can we raise HDL cholesterol levels?
The cornerstone in treating low HDL cholesterol is to address its risk factors; thus weight loss via a healthy diet, smoking cessation, and exercise increase blood levels of HDL cholesterol.

The greater the weight loss and reduction in waist circumference, the greater will be the increase in the HDL cholesterol level. In general, for every 6 pounds of weight loss, HDL may increase by 1 mg/dL. Losing weight can be achieved by cutting about 500 calories from your daily food in-take, and making healthy choices that will improve cholesterol levels but not sacrifice nutrition. Increased fish and reduced carbohydrates in the diet are both associated with higher HDL levels. The Mediterranean diet, which is rich in whole grains, fruits, vegetables, legumes, and olive oil, is also associated with high HDL levels. Soluble fibers are found in oats, fruits, vegetables, and legumes, and result in both a reduction in LDL cholesterol and an increase in HDL cholesterol. At least two servings per day of soluble fibers is recommended.

While limiting total fat in the diet is good for weight reduction as well as cholesterol control, eliminating fat is not recom-mended since this can result in a deficiency in the essential fatty acids. These are fatty acids that have vital functions, but cannot be synthesized by the body itself. A sensible guide on dietary fat is limiting this to 30-35 percent of the total daily calories, and substituting mono- and polyunsaturated fats for saturated and trans fats. Monounsaturated fats such as canola oil, avocado oil, or olive oil and fats found in peanut butter can increase HDL cholesterol levels without increasing total cholesterol. Avoid foods that have trans fat, which is commonly found in processed food, since it not only reduces good cholesterol but increases bad cholesterol as well. As a guide, trans fatty acids are present if the nutrition label reads “partially hydrogenated vegetable oils”.

Diet alone may not be enough to increase HDL cholesterol. Regular aerobic exercise, which refers to any exercise that increases your heart rate for 20-30 minutes, may be the most effective way to increase HDL cholesterol levels. The duration of the exercise, rather than intensity, is the more important factor if we’re aiming for higher HDL cholesterol levels. The recommended frequency of exercise is at least 4-5 times a week. Doing this regimen for about two months can raise HDL levels of otherwise healthy, sedentary adults by about 5 percent.

Lastly, if you smoke, quitting now will result in an increase in HDL levels by up to 15-20 percent. This definitely makes it worth keeping the cigarettes away for good. On the other hand. alcohol, particularly red wine, can significantly increase HDL cholesterol levels. This benefit should however be weighed against the potential risks of alcohol consumption.

Not all patients with low HDL cholesterol levels will respond well with lifestyle modification only. Heredity may play an important role in regulating cholesterollevels, and genetic mutations may be present in some of these patients. Thus, these patients may require medication in addition to lifestyle modification.

Niacin is the most potent drug available for increasing HDL cholesterol levels. Among the several forms of niacin, only nicotinic acid has been shown to raise good cholesterol levels. Intake of this drug should be closely supervised by a physician due to its possible adverse effects of flushing, itching, and hot flashes. Also, when taking a combination of niacin and a statin (another anti-cholesterol drug) such as simvastatin, atorvastatin, rosuvastatin, etc, patients with low HDL should not take vitamin E, C, or beta-carotene supplements since these agents may impair ability of the statin and niacin to raise HDL levels.

The medications fenofibrate and gemfibrozil can also help increase HDL cholesterol levels. These are particularly effective for patients with elevated triglyceridesaside from low HDL. Fish oil supplements rich in omega-3 fatty acids can also raise HDL cholesterol levels. If you are diabetic, the anti-diabetes drug class thiazolidinedione (e.g. pioglitazone), has been shown to help increase good cholesterol.

Knowing all these, the last question is: how often should I have my cholesterol checked? The NCEP-ATP III recommends that a fasting lipid profile be obtained in all adults 20 years old and above at least every 5 years; more often if one has other cardiovascular risk factors. For diabetics, the American Diabetes Association recommends checking cholesterol levels at least once a year. The target HDL is >40mg/dL for males and >50mg/dL for females.

Cardiovascular disease has many risk factors, and HDL cholesterol level is only one of them. To address all of the risk factors and to achieve overall health, the age-old advice still holds: eat right, foster clean living, and keep on moving!

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