Fats and cholesterol

As we know cholesterol has two main components, low-density lipoprotein (LDL) and high-density lipoprotein (HDL). Too much LDL can cause the sticky cholesterol to become lodged on the walls of the arteries, restricting the diameter of the artery itself. This clogging of blood vessels with fatty deposits and the build-up of plaque is known as atherosclerosis. In the western world, atherosclerosis contributes to 1 in 4 deaths.

The amount of cholesterol produced by the body varies from individual to individual. It can also vary as a result of the dietary intake of cholesterol, but this is generally very little. Instead, one of the biggest factors associated with high cholesterol is fat. The consumption of high levels of saturated fats are known to increase blood cholesterol levels.

Saturated fat

Saturated fat has been shown to increase LDL cholesterol more than any other component found in the diet. However, its role in increasing cardiovascular disease risks is widely controversial. Fresh studies haven't shown any real association between the intake of saturated fat and cardiovascular disease.

Instead, high levels of saturated fat increase the levels of LDL cholesterol travelling in the bloodstream, which is a risk factor for cardiovascular disease.

However, what is widely accepted by the medical profession to be bad for health is a subsection of saturated fat known as trans fats.

Trans fat

Trans fats are found in foods such as cakes, biscuits, and deep fat fried foods. They are produced from the partial hydrogenation of liquid plant oils in the presence of heat, a vacuum or a metal catalyst.

Alternatively, they can also be found in meat and dairy products naturally. Particularly in sources from ruminants, animals such as cows who are able to ferment plant-based foods to gain the nutrients they require before digestion.

Fat in diets

A diet high in saturated and trans fats can interrupt the balance of good and bad cholesterol. For example, HDL cholesterol is required to remove excess cholesterol from the tissues and transport it to the liver where it can be excreted in the faeces as bile. When there is a continuous consumption of trans fats however, there is an increase in LDL cholesterol and a reduction in the good cholesterol needed to take away the excess.

Another type of fat that is responsible for increasing LDL cholesterol are refined carbohydrates. These are found in foods like cakes and biscuits as well as fizzy and sugar intense drinks.

Fats such as these should be swapped for unsaturated fats such as:

  • Polyunsaturated fat
  • Sunflower oil
  • Nuts
  • Seeds
  • Oily fish
  • Monounsaturated fats
  • Rapeseed oil
  • Nuts
  • Avocado
  • Sunflower oil

Unsaturated fats

Unsaturated fats can lower the levels of bad cholesterol circulating in the blood, protecting against heart disease. Wholegrains are another good example of foods that can help to reduce saturated fat intake. Grains such as whole-wheat bread, brown rice, cereals, and oats are all good examples and also key ingredients of the Mediterranean diet.

What should we believe?

It is clear more research is needed to back up the current UK guidelines with reference to the amount of fat we should eat as part of our diet. However, it is always a good idea to ensure a healthy, balanced diet.

Eating a diet similar to the one consumed in the Mediterranean has biologically been shown to lower levels of LDL cholesterol. Yet, scientists are still not completely sure what elements of the diet contribute to its effectiveness.

In summary, although cholesterol is an essential part of our diet needed for a variety of bodily functions, too much bad cholesterol can leave us susceptible to serious health complications such as heart disease and strokes.

Fats particularly saturated fats have been shown to increase circulating levels of bad cholesterol in the blood and in some cases even reduce the good cholesterol needed to remove the excess. Lowering our intake of saturated fats can improve our health and life expectancy.

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Aisling Moran BSc (Hons)

Written by Aisling Moran BSc (Hons)

24th Jun 2021 • 4 min read