What is Cholesterol?

Cholesterol is a type of fatty waxy substance created by the liver. The body needs some cholesterol to function correctly, as cholesterol provides the building blocks needed to make;

  • hormones (such as cortisol, testosterone and progesterone)
  • bile acids (needed to help digest and absorb fats consumed)
  • vitamin D (which is very difficult for majority of us to obtain in sufficient amounts especially during the winter months)

However, too much cholesterol circulating in the blood is harmful to healthy bodily function.

Too much cholesterol in the blood can clog the arteries – the build up of fatty deposits in the artery walls causes arteries to thicken and narrow. Narrowing of these blood vessels can lead to a heart attack or stroke.

High cholesterol is one of the main risk factors for cardiovascular disease (CVD) (the general name for all diseases of the heart and circulation).

Cholesterol often gets a bad reputation, but not all cholesterol is harmful. Cholesterol is transported around the body by ‘lipoproteins’. ‘Lipo’ comes from the Greek word for ‘fat’, so think of it as Lipo (fat aka cholesterol) + protein = lipoprotein.

There are two main types of cholesterol both with differing functions in the body:

  1. HDL (High-Density Lipoproteins) – this type of cholesterol contains a lot of protein and relatively little fat, so it is very dense (aka high-density). HDL carries excess cholesterol away from the arteries to the liver to be removed from the body. This is beneficial as it removes unnecessary cholesterol, reducing the risk of it building up and clogging the arteries. HDL therefore has a protective effect against diseases of the heart.
  2. Non-HDL (Non-high density lipoproteins) – this type of cholesterol carries cholesterol from the liver to the body cells and tissues. Unlike HDL, we do not want high levels of non-HDL in the blood because if it builds up overtime it will cause the arteries to narrow and become blocked, increasing the risk of heart attack or stroke.

HDL has three main effects:

  1. Cholesterol removal – return excess cholesterol to the liver to be recycled or removed from the body.
  2. Anti-inflammatory effect – protect artery walls from damage by LDL cholesterol.
  3. Anti-oxidant effect – protect blood cells/tissues from damage.

Healthy HDL levels = 1.3 – 1.4mmol/L (higher levels may not offer additional protection)

  • Men = >1.1mmol/L
  • Women = >1.2mmol/L

Why is high cholesterol a health risk?

A build-up of non-HDL cholesterol in the arteries causes them to harden and narrow, making it more difficult for blood to flow around the body.

Advice to lower your cholesterol:

  1. Choose healthier fats – eat less saturated fats by replacing them with unsaturated sources. Foods high in saturated fat include animal products like fatty, processed meats (sausages, bacon, burgers, pies), full-fat dairy products, biscuits, cakes and pastries, butter, ghee, lard, coconut and palm oil.

Foods high in unsaturated fat include oily fish (salmon, mackerel, sardines), sunflower and soya spreads, olive and rapeseed oil, avocado, nuts and seeds.

  • Check food labels – use the colour-coding system on the front of pack labels to help purchase lower fat options. Opt for food which are green or amber for ‘saturates’ and limit intake of those which are ‘red’.
  • Eat more high-fibre foods – switch to wholegrain carbohydrates (wholegrain rice/pasta/bread/cereals), aim for at least 5 portions of fruit and vegetables daily, increase intake of lentils, beans, oats, nuts and seeds. By eating these foods, you also displace the foods that are higher in calories and saturated fats so a double benefit.
  • Exercise more regularly – aim for at least 150mins (2.5 hours) of exercise per week.
  • Stop smoking – contact your GP, the NHS Stop smoking service or download the free NHS Quit Smoking app for useful tips to help stop. The benefits of this are really wide reaching for all aspects of health and wellbeing.
  • Reduce alcohol intake – try to avoid drinking more than 14 units a week, have several drink-free days during the week and avoid drinking a large amount in one setting.

Sharon Madigan RD, PhD, FFSEM (Hons)


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