The proportion of people with high 'bad' cholesterol levels has dropped in the last decade, a national survey has found
By Joan Chew, The Straits Times, 2 May 2013
Singaporeans appear to be taking better care of their heart health, recent national figures suggest.
For instance, cholesterol levels have improved, particularly levels of so-called "bad" cholesterol, or low-density lipoprotein (LDL).
The National Health Survey 2010 showed 15.2 per cent of Singapore residents aged 18 to 69 years had high levels of LDL in 2010, down from 20.3 per cent in 2004 and 29.1per cent in 1998, after adjusting for an older population as an ageing population would see higher rates of cholesterol.
It may be one of the reasons that the rate of heart attacks per 100,000 people has fallen, from 230 in 2008 to 217 in 2011, after adjusting for an older population, according to the Ministry of Health.
High cholesterol is one of several risk factors for cardiovascular disease, a leading cause of death worldwide. In Singapore, it accounted for one in three deaths in 2010.
There are other reasons as to why heart attack rates may have dropped, noted Dr Raymond Wong, a consultant at the cardiac department at the National University Heart Centre, Singapore.
The National Health Survey 2010 showed the prevalence of hypertension dropped from 32.5 per cent in 1998 to 23.5 per cent in 2010, after adjusting for an older population.
However, other risk factors for cardiovascular disease - obesity, diabetes, smoking and lack of regular exercise - have all gone up between 2004 and 2010.
These figures show that it is very likely the drop in cholesterol and hypertension rates are the main contributors to the fall in heart attack rates, said Dr Wong.
DANGERS OF HIGH CHOLESTEROL
Cholesterol is necessary for the formation of healthy cells but it also contributes to atherosclerosis, the underlying cause of many cardiovascular diseases.
In atherosclerosis, excess cholesterol in circulation is deposited into cells in the artery walls and gradually forms a fatty deposit called plaque.
Atherosclerosis restricts blood flow through the narrowed artery, leading to symptoms of chest pain called angina.
When the plaque ruptures, a blood clot will form which may completely block blood flow in the artery.
LDL cholesterol transports cholesterol from the liver to tissues of the body. High-density lipoprotein (HDL) cholesterol - "good" cholesterol - removes excess cholesterol from the tissues and brings it back to the liver for removal from the body.
What the national survey does not show is how many people with hyperlipidemia, or high cholesterol levels, have lowered their LDL levels through taking cholesterol-lowering drugs, said Dr Wong.
So it could well be that those already diagnosed with the condition are keeping it under control with medication.
Still, doctors are encouraged by the trend, which they feel is a sign of a population becoming more health conscious and aware of how to achieve good health.
While obesity, diabetes and high cholesterol all require a person to adopt healthier lifestyles, some lifestyle changes are easier to achieve than others.
Dr Wong pointed out that obesity is probably the hardest risk factor to manage, since there is no "magic bullet or drug" for one to lose weight.
Dr Tong Khim Leng, the chief of cardiology at Changi General Hospital (CGH), has observed more people being aware of the importance of regular exercise and a diet low in saturated fat.
And more people are finding out their cholesterol levels because of regular health screenings offered by company health insurance policies, said Dr Tan Chong Hiok, a senior consultant at Parkway Heart and Vascular Centre.
He said: "We are able to treat these patients earlier and data has shown that treating them with statin results in a relative risk reduction of up to 50 per cent in preventing cardiovascular disease."
TARGET CHOLESTEROL LEVELS
Doctors say routine screening for cholesterol should start from 40 years of age, and even earlier for people with heart disease or multiple risk factors.
A person's target cholesterol level is dependent on his risk of cardiovascular disease, based on well-known risk factors such as age, ethnic group, smoking status, cholesterol and blood pressure. This can be calculated with a local version of the Framingham risk score.
The higher a person's risk, the lower will be the goal level for LDL cholesterol.
For instance, a high-risk patient, such as one who has heart disease, will need to keep his LDL cholesterol under 2.6 millimoles of cholesterol per litre of blood (mmol/L), compared with a low-risk patient whose target LDL cholesterol is under 4.1mmol/L.
Adjunct Assistant Professor David Foo, the head of the department of cardiology at Tan Tock Seng Hospital, said diabetes and smoking, coupled with high cholesterol, raise a person's cardiovascular risk because they damage blood vessel walls and make it more likely for blood clots to form.
Patients will always be advised to make lifestyle changes - lose weight, exercise regularly, stop smoking and drink alcohol in moderation.
If these do not improve their cholesterol levels enough, medication is prescribed, said doctors here.
Statins is the most common class of cholesterol-lowering medication, said doctors, with seven or eight out of 10 patients being put on statins.
In April 2009, businessman Chua Tiat Beng, 55, was behind the wheel of his car when he broke out in cold sweat and felt a tightness in his chest.
The father of two went straight to a general practitioner, who recognised the signs of an impending heart attack. At Tan Tock Seng Hospital, Mr Chua underwent an emergency angioplasty to unclog a blocked artery. While in hospital, he learned that the first health screening he had been to just a week before had picked up high cholesterol levels.
As he was also a smoker and above 45 years old, he was at high risk of developing cardiovascular disease.
He said: "When people are not sick, they never heed good advice."
He now smokes less, watches his diet, jogs twice a week and takes cholesterol-lowering medication and aspirin to prevent clots from forming around the stent. A blood test last December gave him a clean bill of health.
Lifting the lid off statins
The most commonly prescribed class of cholesterol-lowering drugs is statins, which reduce the level of low-density lipoprotein cholesterol (LDL), commonly called "bad" cholesterol, by blocking an enzyme that produces cholesterol in the liver.
Now, a study by the Singapore Heart Foundation sheds light on the most common misconceptions about statin use.
Published in the Singapore Medical Journal in January, the study was funded by Swedish drug-maker AstraZeneca, which makes statins.
A total of 365 people, aged 30 to 69, were interviewed in 2009. Of these, 104 had dyslipidemia (for example, high total cholesterol levels or high levels of triglycerides) diagnosed within the last five years.
The authors reported that only 11per cent of the total respondents knew their actual cholesterol levels. Among those with dyslipidemia, it was slightly higher at 17.3 per cent.
Mind Your Body gets one of the study authors, Associate Professor Terrance Chua, chairman of the Singapore Heart Foundation and the deputy medical director of National Heart Centre Singapore, to clear up the misconceptions.
1. People with high cholesterol levels usually have symptoms such as breathlessness or chest pain.
Survey finding: 64.9 per cent of respondents agreed.
The reality: High cholesterol levels usually cause no symptoms, unless they lead to a blocked artery that affects the flow of oxygen-rich blood to the heart muscle and causes chest pain (angina). Chest pain is also a key warning symptom of a heart attack.
Breathlessness can also be caused by asthma or heart failure, which is a weakening of the pumping action of the heart. Therefore, it is important to check one's cholesterol levels even when there are no symptoms.
2. Once cholesterol is under control, the person can stop taking medication and it will continue to be under control.
Survey finding: 42.8 per cent of respondents agreed.
The reality: If medication is required, it has to be taken consistently.
An individual's cholesterol levels will be the net effect of medication plus lifestyle changes.
If nothing else - such as diet, exercise habits and smoking - changes and medication is stopped, the cholesterol levels will gradually return to pre-medication levels. Even if lifestyle changes are adopted, cholesterol levels may not drop as much without medication.
3. Once a person is started on the cholesterol medication, it is not safe to stop.
Survey finding: 58.9 per cent of respondents agreed.
The reality: There is no immediate danger to stopping cholesterol medication and may be necessary if a person cannot tolerate its side effects. The most common side effect of statins is muscle ache.
More aggressive lifestyle changes or a different class of drugs may then be needed to bring down cholesterol to the desired levels.
Apart from the problem of cholesterol levels returning to pre-medication levels, there is no additional risk to stopping medication.
A doctor will make the judgement call as to the need for medication and its required dosage.
4. It is healthier and safer to take herbal medicines or supplements than prescribed Western medication.
Survey finding: 33.2 per cent of respondents agreed.
The reality: Some herbal supplements, such as red yeast rice preparations, can lower cholesterol levels because they contain naturally occurring statins which are similar to those in mainstream medicine.
However, many herbal preparations are not subject to the rigorous testing that Western drugs must undergo. It is therefore not correct to assume that herbal medicine or supplements are safer or more effective than prescribed Western medication.
5. Diet and exercise are equally effective at lowering cholesterol as medication.
Survey finding: 87.8 per cent of respondents agreed.
The reality: Medication is often considered only after lifestyle changes have been made.
For many patients, especially those with heart disease, achieving optimal target cholesterol levels is difficult without the use of medication.
6. One of the side effects of the long-term use of medication such as statins is damage to the kidney.
Survey finding: 54.5 per cent of respondents agreed.
The reality: Studies overall do not report long-term adverse effects of statins on kidney function. But at high doses, there is a rare risk of severe muscle inflammation which can lead to kidney injury. In one study, the risk is estimated at less than one per 10,000 patients.
7. One of the side effects of the long-term use of medication such as statins is damage to the liver.
Survey finding: 53.8 per cent of respondents agreed.
The reality: Minor elevations in liver enzymes have been reported with cholesterol-lowering medication.
But last year, the United States Food and Drug Administration allowed labels of statins to be revised to remove the need for routine monitoring of liver enzymes in patients taking statins.
This followed randomised, controlled trials of statins which showed no higher incidence of significant liver disease in patients taking statins compared with a placebo group.
Eat wisely
Singaporeans could do a little better when it comes to making good food choices.
The National Nutrition Survey 2010 showed the mean cholesterol intake for adult Singapore residents was 341mg per day.
More than half, or 54.9 per cent, of respondents met or surpassed their recommended daily intake.
A plate of oyster omelette chalks up 350mg of cholesterol, while a teaspoon of butter contributes to 40mg.
Cholesterol in the body comes from two sources: 80 per cent of it is made in the liver and the rest comes from a person's diet. So people should watch their dietary cholesterol, which is contained in food such as eggs and shellfish.
In addition, two to three out of five to seven servings of carbohydrates eaten daily should come from wholegrain products.
These are good sources of soluble fibre which have the ability to bind cholesterol in the gut, reducing its absorption and increasing its excretion.
Also, not all fats are equal or equally bad. Eat saturated fats, found in dairy products and meat, sparingly as it increases low-density lipoprotein (LDL) cholesterol levels and the corresponding total cholesterol levels.
Avoid trans fats, made from the hydrogenation of vegetable oil, which lowers high-density lipoprotein (HDL) cholesterol levels and increases LDL cholesterol levels.
The best fats to consume are unsaturated fats as well as Omega-3 fatty acids.
What are the top five things one can do to have a cholesterol-lowering diet?
KNOW YOUR MEATS
Choose leaner cuts of meat, such as loin or breast meat. Avoid sausages, Chinese sausages and luncheon meat.
Limit intake of red meat, such as beef, lamb, duck and goose, as they are higher in fat than white meat such as chicken and pork.
Remove skin and visible fat from poultry.
CHOOSE HEALTHIER OILS
Choose healthier oils for cooking, such as canola, olive and sunflower oils. Avoid tropical oils such as palm oil and coconut milk. Replace coconut milk or coconut cream used in cooking with skimmed milk or low-fat milk.
When eating out, ask for no or less oil to be added to food.
BE AWARE OF COOKING METHODS
Adopt healthier cooking methods such as steaming, boiling, grilling, roasting, baking and stewing, instead of deep frying. For example, it is healthier to eat grilled fish and baked potatoes instead of fish and chips.
Use a non-stick pan when cooking to reduce the use of cooking oil.
Scoop out the layer of solidified fat on top of chilled stews, casseroles and soups before heating up and serving.
When eating out, choose soupy dishes instead of fried dishes. For example, opt for beehoon soup instead of fried beehoon. Also, choose boiled wantons (dumplings) instead of fried ones.
LIMIT CHOLESTEROL-RICH FOOD
Eat animal organs, such as pig liver or kidneys, no more than once a month and even then, in small portions.
Consume egg yolks no more than thrice a week. Have seafood, such as shellfish, prawns and crabs, not more than twice a week.
BE A WISE SHOPPER
Choose products with the Healthier Choice Symbol as they are lower in total fats and saturated fats compared with other products in similar categories.
These products also have no trans fat or negligible amounts of it per serving.
Read the ingredient list to identify products that contain vegetable shortening and hydrogenated or partially hydrogenated oils, as they are high in saturated and trans fats. Choose these products less often.
Sources: Mr Gary Chiah Tung Lin, a dietitian in the department of dietetics at Singapore General Hospital; Ms Agnes Lim, a pharmacist at Changi General Hospital; Ms Lim Su Lin, chief dietitian at National University Hospital; Health Promotion Board
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