Summary of Part 1
- In this weeks article on cholesterol, we break down what exactly cholesterol is and its role in the body.
- We dive into the different types of cholesterol and the confusion that exists around them.
- We discuss the relationship that our diet and the foods we consume has on our cholesterol levels and how one size rarely fits all.
Healthy cholesterol levels with sensible food choices – Part 1
Cholesterol and its relationship with health is a hugely complicated topic that has been researched and debated for decades. To date, the exact function and optimum level of cholesterol is not comprehensively understood. What’s more, renowned researchers still debate over the specific dietary recommendations to “optimise” cholesterol levels in the body. Due to the complexity of cholesterol’s role in health and the need to provide some background on the topic, this article will be one of a two part series. This week’s article will focus on defining cholesterol and the consequences of cholesterol imbalance, whereas next week’s article will focus specifically on which foods you should eat to obtain healthy cholesterol levels and thereby may help to reduce the risk of cardiovascular disease and coronary heart disease.
What is cholesterol?
Cholesterol is a tiny organic molecule that presents as a soft, waxy substance in the body. Cholesterol can be consumed through the diet but the vast majority of cholesterol present in the body is produced mainly by the liver (approximately 75%). Cholesterol is required for numerous functions including cell protection, hormone production and the making of bile. In fact, cholesterol is so important that if you didn’t eat any cholesterol-containing foods, your body will still produce enough of it to carry out these vital functions. A huge number of factors such as genetics, nutrition, exercise and other lifestyle factors can influence the type and amount of cholesterol in the body.
As cholesterol plays such an important role in general health and disease risk, cholesterol management and reducing the risk of diseases associated with cholesterol imbalance has become a hugely important topic.
Good cholesterol and bad cholesterol
Part of the confusion surrounding cholesterol in diet and health is that there are a variety of types cholesterol with different functions and different meanings in terms of disease risk. High density lipoprotein (HDL) cholesterol is often referred to as “good” cholesterol and so having higher amounts is suggested to help protect the cardiovascular system. Low density lipoprotein (LDL) cholesterol is considered the “bad” cholesterol, and with very-low density lipoprotein (VLDL) cholesterol linked to a greater risk of arteriosclerosis and cardiovascular disease.
Due to their hydrophobic nature (resistance to water) cholesterol cannot freely travel in the blood stream by itself and must be transported in tiny packages called lipoproteins (lipid + protein). When cholesterol is measured in the blood, a measurement is usually taken of the total cholesterol being transported by HDL or LDL. However, when assessing the health risk associated with cholesterol levels in the body, it is not only the amount (number) of cholesterol present that is important but also the size (density) of the molecules. For this reason, it is important that your doctor offers comprehensive feedback on cholesterol test results and not just a “total” cholesterol measurement.People with a large number of VLDL cholesterol are suggested to have a greater potential health risk than those with a high total cholesterol or LDL cholesterol level. If you want to prevent or lower the risk of developing atherosclerosis you must aim to reduce the number of LDL cholesterol and in particular VLDL particles, circulating in the blood.
Cholesterol – What’s the problem?
As I have already stated cholesterol is vitally important for multiple functions in the body, so when or why does the problem occur? Our arteries are lined by a one cell layer called the endothelium. Blood that contains cholesterol and many other components is in constant contact with the inner lining of our arteries. The problem occurs when the LDL particles attach to the arterial wall and elicits an inflammatory immune response. Our immune system responds to this attached LDL particle by producing immune cells that go to the site and try to remove the LDL particle. If there are only a small number of particles, then the immune response can remove the LDL particles efficiently, but if there are a large number of LDL particles attached to the endothelium, then the immune cells are unable to dislodge the particle. As a result, a plaque builds up, narrowing the arterial space that blood flows through. This can lead to reduced blood flow and a myriad of health issues such as an increased risk of heart attacks, stroke and other cardiovascular issues.
HDL cholesterol on the other hand is said to offer protection to the body’s cardiovascular system by helping to remove LDL cholesterol that builds up as arterial plaque. Multiple studies have illustrated that having high levels of HDL cholesterol can reduce the risk of cardiovascular and heart disease even when LDL levels are high. It is therefore strongly recommended that not only should someone with sub-optimal cholesterol levels seek to reduce LDL cholesterol, but should also aim increase the level of HDL cholesterol. Improving the overall ratio of HDL cholesterol to LDL cholesterol is most likely the most effective strategy for those aiming to reduce the risk of cardiovascular-related diseases.
Cholesterol and diet
The type and level of cholesterol in the body is affected by a multitude of factors including genetics, dietary components such as the presence of refined carbohydrates or a lack of fibre, and a lack of physical activity. Traditionally people with high cholesterol would have been told to avoid all fats and increase their intake of dietary carbohydrates with little guidance on what type. It’s easy to see how this type of ‘blanket advice’ that was commonly given to the public, could lead to an increase in different types of carbohydrates, i.e those with added sugars, in order to compensate for the loss of energy and satiety associated with eliminating fats, including healthy fats, from the diet.
What we now know is that such an approach can worsen cholesterol imbalances by increasing LDL cholesterol levels even further, without increasing the “good” HDL cholesterol. Despite what people may tell you or what you may have read, it is simply not true that all dietary cholesterol, fat and even certain saturated fats are “bad” for your health. The commonly-held opinion that cholesterol and fats found in foods such as butter, whole milk, eggs and coconut oil are foods that should be avoided at all costs again is simply not true. For example, research published in the American Journal of Clinical Nutrition in 2010 as a large meta-analysis of prospective studies involving almost 350,000 participants found no association between saturated fat and heart disease. As the British philosopher and logician Bertrand Russell once put it: “The fact that an opinion has been widely held is no evidence whatever that it is not utterly absurd”.
A much greater understanding of how fat is metabolised coupled with extensive research has dispelled the myth that dietary fats and cholesterol-containing foods lead to a greater risk of disease. In fact, rather than increasing the body’s cholesterol levels, much of the cholesterol we eat (known as “dietary” cholesterol) is actually excreted by the body and not stored at all. That dietary cholesterol from foods such as eggs contributes very little to total cholesterol levels in the blood provides just another example of how genuinely healthy and nutrient-rich foods can mistakenly get a bad name.
Recommendations on dietary best practice to achieve healthy cholesterol balance should only be made based on relevant scientific data, and not on out-dated research or stubborn opinion. Obviously, individual responses to dietary patterns and interventions should be closely monitored as people do respond differently to foods that they consume, and one size will rarely fit all in dietary and lifestyle terms. Check back next week to discover the key dietary considerations for balancing cholesterol levels with the aim of reducing the risk of cardiovascular disease.
To get you started, here are some cholesterol-friendly recipes!
Pecan Salmon with Cranberry Quinoa Salad
No Bake Chocolate Protein Balls
References:
Siri-Tarino, P.W., Sun, Q., Hu, F.B. and Krauss, R.M., 2010. Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease. The American journal of clinical nutrition, 91(3), pp.535-546.