Cholesterol in foods: Do we really have to worry about it?

Cholesterol is one of the most debated issues in the health and fitness industry; on one hand, there are those who expound that we should not be consuming cholesterol, and on the other, there are those who assert that cholesterol in food doesn’t affect the cholesterol level in our body. It seems that the former group is winning and, as a result, we are completely avoiding whole classes of foods such as eggs which may actually be doing us more harm than good.

The reason both camps exist is due to the divided cholesterol research literature coupled with various media taking different perspectives to align with the author’s intention. Before finding out if cholesterol is good or bad, it would helpful to be given a full picture of what cholesterol is.

What is cholesterol?

Cholesterol is a waxy, fat-like substance found in the cells of humans. They are needed to synthesise our hormones and the bile for the digestion of fat and vitamin D from sunlight.

As cholesterol is a fat, it is by nature hydrophobic meaning that it is immiscible with blood. In order to be transported in the blood stream, cholesterol binds to certain proteins known as lipoproteins. This results in the formation of a few end-products commonly referred to as low-density lipoprotein (LDL) and high-density lipoprotein (HDL).

Total cholesterol

Total cholesterol comprises of LDL, HDL, and triglycerides

High-density lipoproteins (HDL)

High-density lipoproteins, commonly referred to as ‘good’ cholesterol, are compounds that remove arterial plaque. High levels are associated with a lowered risk of cardiovascular disease (CVD)

Low-density lipoproteins (LDL)

Low-density lipoproteins are also known as ‘bad’ cholesterol. They are known to deposit cholesterol on arterial walls forming plaque. The build-up of plaque over an extended period of time leads to the narrowing of these walls, causing a condition known as atherosclerosis which leads to ischaemic heart diseases such as stroke and myocardial infarction.

Triglycerides

Triglycerides are found circulating in the blood found at relatively elevated levels after a meal. Factors which cause raised triglycerides are smoking, excessive sugar consumption, low physical activity, alcohol consumption and being overweight or obese.

Unknown to some, the body actually does produce cholesterol and in quantities more than what you typically can consume. This is because cholesterol is essential for the proper functioning of the body. However cholesterol levels in the body are tightly regulated by the liver, keeping it fluctuating within a very tight band.

What does all of this information mean and what should I be looking out for?

When you consume too much cholesterol, your liver produces less of it and vice versa because excessively high levels of blood cholesterol could potentially be harmful. In other words, your body can pretty much self-regulate cholesterol levels.

Having said this, some evidence presented showed that a chronically excessive intake of dietary cholesterol from foods (such as eating 10 eggs a day) does increase total blood cholesterol in a linear fashion to some extent. Do note that this is especially bad in some individuals who are hyper responders. However the association between raised cholesterol and CVD risks have been proven inconclusive.

In many reports documenting the relationship between dietary cholesterol and CVD^, many fail to take into account confounding factors such as saturated fat intake which is almost always associated with increased blood cholesterol levels.

Apart from total cholesterol levels, we should be looking out for the increase in LDL levels and HDL to total cholesterol ratios as these are more accurate markers of CVD. The recommended LDL and HDL levels in Singapore are <2.6 mmol/L and 1.0-1.5 mmol/L respectively.

Ratio of HDL to cholesterol should ideally be lower than 1:3 which represents a lower CVD risk.

^For instance,”The Relationship Of Dietary Cholesterol To Serum Cholesterol Concentration And To Atherosclerosis In Man” and "Dietary Cholesterol And Cardiovascular Disease: A Systematic Review And Meta-Analysis" in the American Journal of Clinical Nutrition.

7 tips to lower cholesterol

With this in mind, we should be trying to optimise our diets, making small, sustainable changes in order to achieve desirable LDL levels and HDL to cholesterol ratios.

1. Increase fibre intake

Fibre has been strongly associated with a lowered risk of CVD due to the beneficial compounds found in high fibre foods and not to mention fibre itself. For example vegetables contain a compound known as sterol which has cholesterol-lowering properties. Not only this, increased fibre intake can improve bowel movement and prevent colorectal cancer.

To achieve adequate this, we should try to consume at least 2 servings of fruit* and vegetables** a day and try to replace white rice with brown/red/black rice!

*1 serving of fruit: a medium apple /pear/ banana or a slice of watermelon/ papaya/ honeydew

**1 serving of vegetable: a generous handful

2. Choose lean meats

Wherever possible, it is always prudent to choose leaner meats and low-fat cooking methods. Lean(er) meats most definitely do not have to be boring. For example if you find yourself eating out in a restaurant, a sirloin steak (fat removed) or roasted chicken breast (skin removed) would be a great alternative to the ribeye steak.

3. Replace saturated fat with unsaturated fat

Aim to reduce saturated fat consumption and replace it with either poly or monounsaturated fat because this leads helps lower LDL and increase HDL, resulting in dual benefits. Commonplace examples of unsaturated fat are vegetable oil, olive oil and fish oil. Therefore instead of using duck fat to roast vegetables, opt for a similar amount of vegetable oil and you’ll be on your way to a healthier heart!

A good guide would be to consume approximately 30% of your energy intake from fat. 10% of this can come from saturated fat and the rest, unsaturated fat sources.

4. Avoid trans-fat

Trans-fat is probably the most detrimental to LDL levels when compared to other dietary fat sources. It has been proven to have a direct association with blood cholesterol levels. Common food sources of trans-fat are pastries, doughnuts, pizza and margarine which should be consumed on occasion or avoided completely. Doing so also helps you omit saturated fat and sugar from your diet which is a bonus!

5. Watch your cholesterol

Despite the body regulating blood cholesterol, this does not mean that we should go wolfing down eggs at brunch! We should still aim to consume less than 300mg of cholesterol a day and therefore, we should steer clear of cholesterol-rich foods and choose healthier cooking fat. This is because more often than not, these foods contain a large amount of saturated fat as well (butter, ghee, cured meats etc.) which could potentiate the rise in cholesterol levels and increase CVD risks!

6. Stub it

Smoking is extremely detrimental to cholesterol levels. It not only raises LDL levels but triglyceride levels as well! Thankfully, just by quitting smoking, HDL levels can improve in just over three weeks!

7. Exercise

Exercise is just as important as diet, if not more! It not only helps us look and feel good but it also improves our health as it staves off obesity which in turn decreases triglycerides and LDL levels. Not only that, it increases HDL levels, improves insulin sensitivity and decreases blood pressure!

In order to enjoy the whole host of benefits from exercise, we should try to get at least 150 minutes of exercise a week which could be broken down into manageable, sustainable blocks of exercises - for example, 30 minutes a day for five days!