Chances are that you’ve come across the word Cholesterol. It’s a word that almost always comes up in discussions to do with fats in our diets, and rightly so given the role it plays in our health and especially the heart.
But what do you really know about it other than what is randomly mentioned out there? Not much I presume and for that reason we’re going to try and demystify it for you today.
Cholesterol is a type of lipid (fatty substance) which is mainly produced by the liver but can also be found in some foods. Cholesterol plays a very important role in the normal functioning of the body.
Some of its functions include:
- Contributes to the synthesis of cell membranes
- Makes up the bile acids that are vital for digestion
- Helps the body to make vitamin D
- Is a component of many vital hormones
What is the difference between Dietary and Blood Cholesterol?
When talking about cholesterol, most people tend to confuse between dietary cholesterol that is found in some foods and the cholesterol that is circulating in the blood.
Actually, most people don’t have an idea which is which, and so the common assumption is that they’re one and the same thing. That’s quite erroneous. Here’s why.
Often when talking about cholesterol, the one in question is the one found in blood. Blood Cholesterol as its commonly referred to is produced by the liver and circulates around the body in our blood.
It makes about 85% of the cholesterol in our bodies while the rest, about 15%, comes from our diet. This is the dietary cholesterol, and it primarily comes from animal sources such as meat, poultry, seafood, dairy and eggs.
So the next time your doctor oders a blood test to measure your cholesterol levels just know it’s the blood cholesterol that is being measured.
Good and Bad Cholesterol
The cholesterol in our blood is transported by proteins. When these two combine, they form what is referred to as a lipo-protein (“lipo” is for lipid). The two main types of lipoproteins used for this transport are:
- LDL – Low density lipoproteins
- HDL – High density lipoproteins
Good cholesterol is used to refer to HDL. HDL transports cholesterol away from the cells and back to the liver so that it can be broken down or removed from the body as a waste product.
It’s for this reason that HDL is called “good cholesterol” and the higher it is the better.
Bad cholesterol as you might have figured out is the LDL. LDL does the opposite of HDL in that it transports cholesterol to the cells that need it. However, if there’s too much of it for the cells to use, it can build up in the walls of the arteries, increasing one’s risk of developing cardiovascular diseases.
It’s for this reason that LDL is called “bad cholesterol” and the lower it is the better.
From this we can clearly see one is healthier when they have a low LDL and a high HDL. This is because high LDL and low HDL cholesterol levels are both associated with the risk of developing cardiovascular diseases.
A high HDL level is, however, not necessarily more beneficial than when it’s in an adequate amount.
Why high bad cholesterol is not good for you?
Having high levels of the bad cholesterol increases your risk of cardiovascular diseases (diseases that are associated with your heart and blood vessels). These include:
- Atherosclerosis – this is the narrowing of arteries caused by the build-up of fat deposits in the walls of the arteries.
- Coronary Heart Disease – this is a condition where there’s reduced blood flow to the heart muscles due to atherosclerosis of the coronary arteries (vessels that transport blood to the heart muscles).
- Heart Attack – this is a condition where the heart suffers from insufficient blood supply due to the blocking of one of the arteries that transport blood to it.
- Stroke – this is the sudden loss of brain function that occurs when an artery to the brain gets blocked or raptures.
- Transient Ischaemic Attack (“mini-stroke”) – this is a brief disruption of blood supply to a part of the brain caused by a blood clot.
- Peripheral Arterial Disease – this is a condition where there’s reduced blood supply to the leg muscles due to build-up of fatty deposits in the arteries that transport blood to the legs.
Having high cholesterol does not produce signs or symptoms on its own and therefore you should have your blood cholesterol tested routinely so as to ensure the above conditions are prevented.
What causes high levels of bad cholesterol?
The bad blood cholesterol can be increased by a variety of risk factors. The common ones include:
- An unhealthy diet that comprises:
- high intake of foods containing saturated fats like fatty meat, sausages, bacon, butter, cheese, ghee, cream, cakes, biscuits etc.
- foods containing trans fats (explained below) which are found in foods prepared/cooked with partially hydrogenated oils like fried foods, baked goods (cakes, biscuits, cookies, crackers, pie, crusts, frozen pizza etc.), stick margarines, creamer etc.
- low intake of heart-healthy foods (vegetables, fruits, whole grains, fish, healthy fats)
- Lack of regular exercise
- Drinking excessive alcohol
Others risk factors include:
- Having Diabetes, Hypertension, Kidney disease, Liver disease or an underactive thyroid gland – this cause elevated levels of cholesterol.
- Family history of coronary heart disease or stroke.
- Family history of a cholesterol-related condition like hypercholesterolemia (presence of excess cholesterol in the blood).
- Age – cholesterol levels tends to rise as one gets older, and therefore one’s risk of high cholesterol increases with age.
- Gender – men tend to be more prone to high cholesterol than women.
- Race – some ethnicities like South Asians, African and Mexican are more susceptible to higher cholesterol levels.
What are Trans fats?
Trans fats are usually found in partially hydrogenated oils where they are formed artificially. They’re also found naturally in some animal products like milk and meat but in small quantities.
Trans fats raise your bad cholesterol (LDL) levels and lower your good (HDL) cholesterol levels. They’re are considered the worst type of fat you can eat so it’s best to avoid them.
- Why the FDA is phasing out artificial trans fats from the American Food Industry
- Does Blue Band Margarine have trans fats?
Does dietary Cholesterol increase Cholesterol levels?
You’ve probably come across food products claiming to be ‘cholesterol-free’ or ‘heart-friendly’. If it’s an animal-based product then that usually makes sense because as we saw earlier, some of them like meat, dairy and eggs do indeed contain small amounts of naturally occurring cholesterol.
However, if it’s a plant-based product like palm oil, then that’s merely a sale gimmick because other vegetable oils do not contain cholesterol too. This is because dietary cholesterol primarily comes from animal sources.
To answer the question, dietary cholesterol does indeed increase cholesterol levels, but the overall effect is small when compared to the effect by saturated or trans fats.
So, while a product may be cholesterol-free, it may not necessarily be free of these other fats whose effects on raising cholesterol levels are in fact much worse.
Therefore, it’s important to read the food labels and check for these fats regardless of whether the product is cholesterol-free or not. Minimize your intake of saturated fats and generally keep away from foods that contain trans fats.
If you take foods that contain cholesterol like eggs it’s recommended your keep your total cholesterol intake to not more than 300mg daily and 200mg daily if you have high cholesterol, diabetes, or heart disease.
What can I do to lower bad cholesterol and boost the good cholesterol?
Some tips recommended to lower bad cholesterol and increase the good one include:
- Keep a healthy and balanced diet that is rich in vegetables, fruits and whole grains
- Exercise regularly
- Achieve and maintain a healthy weight
- Reduce your intake of foods high in saturated fats
- Avoid foods with trans-fats
- Use unsaturated (poly-unsaturated and mono-unsaturated) vegetable oils like canola, corn, olive, peanut, safflower, sesame, soybean, and sunflower oils
- Avoid Smoking
- Drink alcohol with moderation
- Cut back on refined carbohydrates, e.g. prefer wholegrain varieties of foods such as wholewheat or brown bread over white bread