By nutritiontogo, Nov 10 2015 10:30AM
What is cholesterol?
You've probably heard of cholesterol because it's got a bit of a bad reputation when it comes to heart health and excess weight. However, you may not be entirely sure what it is, or know that it is actually an essential element in the body - despite its negative connotations.
Produced by the liver, it is a fat-like waxy substance that is present in all cell membranes. Your body needs it for a number of processes, including for the manufacture of hormones and vitamin D, as well as other substances that assist digestion. It is also important for brain function and the proper working of neurotransmitters - after all, the brain is at least 60% fat - and cholesterol may even play a role in helping you to resist infection!
Your body makes all the cholesterol it needs. However, it is also found in some of the foods we eat (such as fast foods, animal fats and oils, eggs, liver, fish, shellfish, red meat, dairy and pastries etc). As a result, when our diet includes too many cholesterol-rich foods, it can lead to blood levels that are too high. It is this imbalance which is thought to promote ill-health and disease, such as atherosclerosis.
You might be surprised to see what most of us would consider to be "healthy" foods included in the list above. It is important to note that you do not need to avoid foods that are naturally rich in cholesterol (such as eggs, liver and seafood). This is because, while we would get some cholesterol from these foods, they usually don't need to be limited because they are also naturally low in saturated fat - the key.
It is best to avoid too much saturated fat, which increases cholesterol levels. Instead, opt for foods that contain unsaturated fat (healthy fat), which can actively support healthy cholesterol levels.
Cholesterol healthy foods
In shaping your diet to include more cholesterol healthy foods, it is worth noting that plants do not contain cholesterol. What's more, they are usually low in saturated fat and high in dietary fibre, Omega oils (the good fats) and other valuable nutrients that support heart health, a healthy weight, brain function and immunity.
So, if you are looking to improve your cholesterol levels, fruit, vegetables and other plant-based foods (particularly those rich in plant sterols) should feature heavily in your daily diet. In particular, go for whole grain cereals, soya, beans, pulses, nuts and seeds like:
porridge oats (rich in beta glucans)
adzuki beans, black beans, black-eyed peas, butter beans, cannellini beans, chickpeas, edamame beans, kidney beans, lima beans, mung beans, navy beans, pinto beans, split peas, white beans
vegetables rich in soluble fibre, such as okra, aubergine, turnip, carrots, cabbage and sweet potato
dark leafy greens, rich in magnesium
antioxidant-rich fruits, such as citrus fruits, blueberries, avocados, grapes and tomatoes
soya nuts (also called edamame beans) and other soya foods (such as tofu) rich in isoflavones
and unsalted almonds, pistachios, walnuts, pecans, cashews and peanuts (rich in magnesium and niacin, vitamin B3).
Good examples of heart healthy Omega rich foods include: flaxseeds, walnuts, sardines, mackerel, soybeans, tofu, Brussels sprouts and cauliflower.
The difference between 'good' and 'bad' cholesterol
In understanding how cholesterol can be bad for your health, it can also be helpful to understand how it is transported around the body.
Cholesterol is transported in the bloodstream, packaged with protein in the form of lipoproteins. These come in 2 main types:
1. Low density lipoprotein-cholesterol (or LDL cholesterol): It is this form that has traditionally been viewed as the one chiefly responsible for depositing cholesterol on the inside of the arteries and therefore associated with heart disease and stroke. This is why it is often referred to as "bad" cholesterol.
2. High density lipoprotein-cholesterol (or HDL cholesterol): In contrast, HDL is usually referred to as "good" cholesterol because it is associated with actually clearing cholesterol from clogged arteries.
While this is a nice clear distinction, it is not the whole picture. In recent years, our understanding of the connection between diet, LDL cholesterol and heart health has come a long way as a result of in-depth scientific research. We now know that there are a number of factors at play. For instance, different types of saturated fats and carbohydrates can affect the amount and size of LDLs.
As such, heart disease is not always necessarily associated with total cholesterol levels alone. LDL particle number and size is now considered one of the strongest markers of heart disease risk. Other markers include Lp(a) - a lipoprotein subclass - and homocysteine levels. If you have increased levels of inflammation in your body, this could (at least in part) contribute to increased cholesterol levels.
Staying healthy and the role of your liver
So while cholesterol levels may not be a deciding factor in heart and other aspects of health, it is certainly an important one. The government currently recommends that total cholesterol intake for healthy adults should be around 300mg of cholesterol per day. People with heart disease or diabetes are advised to limit themselves to 200mg, with less than 7% of calories from saturated fat.
Cholesterol is naturally present in your body to do a job; to help your body repair and health. But, as with anything, if it is abused or its balance is disturbed, it can have unintended consequences for our health.
As we have already mentioned above, our diet can have a significant effect on our cholesterol levels (as well as our triglycerides, another type of fat found in the blood). So too can our lifestyle, including factors such as smoking, drinking and levels of stress and physical activity.
However, it is worth noting that the liver is responsible for producing a massive 75% of your cholesterol. So cutting down on cholesterol-rich and fatty foods alone is unlikely to be enough.
Your liver's production of cholesterol is actually influenced by your insulin levels - this is a vital piece of information if you are looking to lower your levels. Why? Well, by optimising your insulin levels and keeping your blood sugar stable, you can help to regulate your cholesterol levels in a proactive way.
Foods that cause your insulin levels to rise (high glycaemic index foods), include refined carbohydrates, grains, sugars, alcohol etc). They contribute to high cholesterol by forcing your liver to make more of it.
So, once again, this largely comes back to dietary choices, staying active and managing your weight. Subject to any advice to the contrary from your doctor or health practitioner, try switching to a low-carbohydrate diet (avoiding refined carbohydrates as much as possible), reduce alcohol and caffeine consumption, stop smoking, avoid sugars and processed fats.
Instead, pack your diet with natural whole foods, such as fruit, vegetables and leafy greens, as well as lean protein (particularly oily fish). These will be naturally high in Omega oils, vitamins and minerals, as well as dietary fibre, flavonoids (such as resveratrol and quercetin) and antioxidants.