Cholesterol is often painted as the villain in the narrative of heart health, but the reality is nuanced.
Here, I will explain what cholesterol is, why it’s essential for your body, and how your diet can significantly impact your blood cholesterol levels – but perhaps not in the way you thought.
What is cholesterol?
Cholesterol is a waxy, fat-like substance found in all cells of the body.
It is crucial for producing hormones, vitamin D, bile (to help you digest foods), brain cells, and cell membranes (the outer bit of your body's cells).
Your body makes cholesterol, and you can also get it from eating animal products.
Good versus bad cholesterol
Cholesterol travels through your bloodstream in small packages called lipoproteins.
There are two main types of lipoprotein, but you also need to be aware that one has two important sub-types.
Low-density lipoprotein (LDL)
Often referred to as 'bad' cholesterol, high levels of LDL cholesterol can lead to a build up of cholesterol in your arteries, increasing the risk of heart disease and stroke.
LDL cholesterol particles can vary in size and density, and these differences can influence their impact on your health.
Small, dense LDL particles are more likely to penetrate the arterial wall and are more prone to oxidation, so they are associated with a higher risk of atherosclerosis and heart disease.
Large, buoyant LDL particles are larger and less dense, making them less likely to penetrate the arterial walls and cause damage. They are considered to be less harmful compared to small, dense LDL particles.
2. High-density lipoprotein (HDL)
Known as 'good' cholesterol, HDL cholesterol helps to remove LDL cholesterol from the arteries, transporting it back to the liver where it is broken down and removed from the body.
How diet influences blood cholesterol levels
You can influence your blood cholesterol levels with your diet. Here are some key dietary factors that impact cholesterol levels.
Trans fats
Found in fried and processed foods, trans fats not only increase LDL cholesterol but also lower HDL cholesterol. They are particularly harmful due to their chemical structure, which makes them unstable and more likely to cause oxidative damage (oxidation).
Oxidation is a process similar to how a cut apple turns brown. In the body, oxidation refers to the damage caused by free radicals – unstable molecules that can damage cells, including those in your arteries.
When LDL cholesterol particles become oxidised (by unstable trans fats), they are more likely to stick to the walls of your arteries, forming plaques that can lead to atherosclerosis (hardening and narrowing of the arteries).
This increases the risk of heart attacks and strokes.
By avoiding trans fats, you reduce the oxidative stress in your body, thereby lowering the risk of heart disease.
Sugar and refined carbohydrates
High intake of sugar and refined carbohydrates can have a major impact on blood cholesterol levels and overall heart health:
Triglycerides: Consuming too much sugar can lead to high levels of triglycerides, which can lead to an increase specifically of small, dense LDL particles that are the type of LDL cholesterol particles that are more likely to contribute to plaque build up in the arteries.
HDL cholesterol: Diets high in sugar can lower HDL cholesterol levels and reduce the body's ability to remove LDL cholesterol from the bloodstream.
Insulin resistance: Excessive sugar intake can lead to insulin resistance, a precursor to type 2 diabetes, which is linked to higher LDL cholesterol levels and lower HDL cholesterol levels.
Inflammation: High sugar intake can promote inflammation in the body, which is a key factor in the development of atherosclerosis and heart disease. Inflammation can also lead to the oxidation of LDL particles, further increasing the risk of arterial plaque formation.
Fibre
Fibre has a positive impact on your cholesterol.
Soluble fibre found in oats, beans, lentils, fruits and vegetables can help to lower LDL cholesterol.
Omega-3 fatty acids
Omega-3 fatty acids have a positive impact on your cholesterol.
Found in fatty fish (like salmon, mackerel, and sardines), flaxseeds, and walnuts, they can help to lower triglycerides and may improve overall heart health.
Wait, doesn't dietary cholesterol influence blood cholesterol?
For many years, it was believed that consuming high-cholesterol foods, such as eggs and shrimp, would directly raise blood cholesterol levels.
However, recent research has shown that, for most people, dietary cholesterol has a relatively small impact on blood cholesterol levels.
The liver regulates cholesterol levels by adjusting the amount of cholesterol it produces. When you consume more cholesterol from your diet, your liver compensates by producing less.
While some people (often referred to as 'hyper-responders') may experience a greater increase in blood cholesterol levels when consuming dietary cholesterol, the overall effect is still minor compared to the impact of trans fats and sugar.
And what about saturated fat?
Found in red meat, full-fat dairy products, and certain oils (like coconut and palm oil), saturated fats have been traditionally linked to higher LDL cholesterol levels.
However, this relationship is complex and somewhat contested in recent research.
Some researchers argue that the type of LDL particles (small, dense vs large, buoyant) and overall dietary context are more important factors.
In conclusion, saturated fats are not be as harmful as trans fats or sugar in the context of a balanced diet, but for some people lowering saturated fat intake may help LDL cholesterol levels.
Quick tips for managing blood cholesterol
Eat less fried and ultraprocessed foods (which contain trans fats).
Eat more healthy fats found in olive oil, avocados, and nuts.
Eat more fibre from fruits, vegetables, whole grains, and legumes.
Choose lean proteins such as lean meats, poultry, fish and plant-based proteins over fatty cuts of meat and processed meats.
Limit sugar and refined carbs (e.g. baked goods).
Incorporate omega-3 fats from fatty fish at least twice a week, or consider plant-based omega-3 sources such as flaxseeds.
Exercise.
Maintain a healthy weight.
Quit smoking.
Please do get in touch if you're concerned about your cholesterol and need some additional support.
Disclaimer
The information and advice I provided here is of a general nature and should never replace individual health or medical advice provided by your doctor or other healthcare professional involved in your care.
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