The latest truths about cholesterol

WITH the recent release of the latest local guidelines on cholesterol in December 2023 by the Ministry of Health and the Academy of Medicine, we need not spend endless hours peering into our mobile phones, scouring for the truths on cholesterol through the various social media platforms. Let us take a walk together through the carefully curated information on cholesterol and distil the essence that is relevant to our daily lives.

Bad cholesterol is the real villain

While almost every adult knows that cholesterol is a type of fatty substance that can accumulate in the wall of arteries and cause narrowing of the arterial channel, is there really such a thing as good cholesterol? The advent of new classes of cholesterol-lowering medication has allowed doctors to delve into the realm of ultra-low levels of low-density lipoprotein cholesterol (LDL-C or “bad” cholesterol), and has confirmed the central role of LDL-C in strokes and heart attacks.

Current evidence supports the view that greater absolute LDL-C reductions are associated with greater reductions in the risk of heart disease and stroke – that is, the lower the LDL-C, the better. In contrast to LDL-C lowering, studies on the elevation of high-density lipoprotein cholesterol (HDL-C) are not correlated with a reduction in cardiovascular events. Hence, the previously termed “good” cholesterol (HDL-C) has failed to live up to its reputation. 

No need to fast

If you have never checked your cholesterol in your entire life, you should do so by the time you hit 40. While the common practice is to fast for about 12 hours before taking a fasting blood sample the next day, recent studies have fortunately shown that the difference between fasting and non-fasting samples is not significant in the large majority of patients. Hence, when you next visit your doctor’s clinic, you do not need to endure a 12-hour fast to test your blood sample. 

How low should the cholesterol be?

While the paradigm of “the lower the LDL-C, the better” holds true, the potential benefit has to be balanced against the cost and effects of medication. Hence, to determine your personal LDL-C targets, you need to understand your risk of getting a stroke, heart attack or blockage of arteries. The higher the risk level, the greater the absolute benefit from lowering LDL-C, and the more the LDL-C reduction will outweigh any potential risks from long-term therapy.

Invariably, those with the highest risks benefit most from lowering their LDL-C. Sitting right at the top of the risk ranking are those with a history of stroke, heart attack and blocked arteries. Those at high risk also include those with inherited severely elevated cholesterol (familial hypercholesterolaemia) and those with diabetes mellitus with diabetic complications. For those in these high-risk categories, an LDL-C level of < 1.8 mmol/l ( < 70 mg/dl) can be considered. Additionally, if you have had a heart attack previously, aiming to reduce your LDL-C to < 1.4 mmol/l ( < 55 mg/dl) may further reduce your risk.

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Lower down the risk ladder are those with uncomplicated diabetes mellitus, chronic kidney disease or uncomplicated familial hypercholesterolaemia (< 40 years of age), where keeping your LDL-C < 2.6 mmol/l (< 100 mg/dl) will suffice.

As the risk profile decreases, the absolute benefit is lower, and the therapeutic LDL-C targets are adjusted correspondingly. Hence, for those who are not in any of the earlier risk categories, an LDL-C < 3.4 mmol/L (< 130 mg/dl) can be considered. However, for this lower-risk group, lifestyle modification is the mainstay of management.

Lifestyle modification

Lifestyle interventions include smoking cessation, weight reduction (for obese individuals) and regular exercise. The 2022 “Singapore Physical Activity Guidelines” published by the Health Promotion Board and Sport Singapore recommend that for substantial health benefits, adults should do at least 150 minutes (2 hours and 30 minutes) to 300 minutes (5 hours) a week of moderate-intensity, or 75 minutes (1 hour and 15 minutes) to 150 minutes (2 hours and 30 minutes) a week of vigorous-intensity aerobic physical activity, or an equivalent combination of moderate and vigorous-intensity aerobic activity, spread over 5 to 7 days in a week.

Dietary tips to reduce the risk of heart attacks and stroke include minimising the consumption of saturated fatty acids (SFAs) and trans fatty acids (TFAs) as both SFAs and TFAs are associated with LDL-C elevation. Daily dietary cholesterol should be reduced to < 300 mg per day. Daily consumption of 20 to 30 g of dietary fibre that contains the fibre B-glucan, such as barley and oats, has been shown to lower LDL-C.

The alcohol conundrum

Earlier observational studies have reported a J-shaped distribution of outcomes with the lowest rates of heart attacks in those with low to moderate alcohol consumption, and higher rates in those who did not drink or have high alcohol consumption. However, this perceived benefit has not been validated in any randomised controlled trial. Furthermore, this J-shape effect has not been seen in studies in Chinese and Indian cohorts.

A 2022 World Heart Federation (WHF) policy brief challenged the perception that low to moderate alcohol consumption is cardioprotective. There is a linear association between regular alcohol consumption of at least 100g per week and an increased risk of stroke, heart failure, fatal hypertensive disease and fatal aortic aneurysm. In patients with severe elevation of triglycerides, consumption of alcohol is associated with an increased risk of inflammation of the pancreas. The latest local guidelines recommend that individuals who do not currently drink should not start, and they do not recommend the consumption of alcohol for its purported cardioprotective effects.

When lifestyle measures fail to reduce the LDL-C levels to desirable levels in the higher-risk groups, medication should be considered. In the next article on cholesterol, we will take a look at the latest therapeutic options and understand how they can reduce our risks of stroke and heart attack substantially.

This article is part of a monthly series on health and wellbeing, produced in collaboration with Royal Healthcare