Blood Cholesterol is Derived from the Liver

Our diets are made up of a number of different components – carbohydrates, proteins and fats, to name a few. Within the body, a part of what we consume is converted into body fat which is essential for normal body function.

The liver produces a component that is released into the blood stream called cholesterol, and this is what is considered to be a reflection of what the fat content in the body. Around 75% of the blood cholesterol is derived from the liver; the remaining 25% from food.

It is common knowledge that high cholesterol is a risk factor for developing heart disease and strokes. Heart disease is the commonest cause of death in the United States, and the American Heart Association estimates that 2,200 people die every day of heart disease in the United States. In this article, we will cover ways to lower cholesterol and discuss in brief the treatments for high cholesterol.

However, before we go ahead, let us take a look at the different kinds of cholesterol.

Types of cholesterol

Having high cholesterol can be a good and bad thing. Broadly classified, there are within the blood ‘good’ and ‘bad’ cholesterol. The good cholesterol is called High Density Lipoprotein cholesterol (HDL) while the bad cholesterol is called Low Density Lipoprotein cholesterol (LDL). There also exists another form called Very Low Density
Lipoprotein cholesterol (VLDL) and triglycerides, both of which are bad cholesterols.

The aim when treating high cholesterol levels is to have a high HDL and low LDL levels in the blood. The table below details the normal cholesterol levels –

Type of Cholesterol

Normal Value
(milligrams/ decilitre)

Total

< 200 mg/dL

LDL

< 130 mg/dL

HDL

> 60 mg/dL

Triglyceride

< 150 mg/dL

 

Now that we have taken a look at the different types of cholesterol and their normal levels, let us discuss how high cholesterol can be reduced.

Why high cholesterol should be treated

Cholesterol forms an essential component of cell walls and is required in the synthesis of a lot of natural products in the body. However, when present in excess, it can deposit on the surface of the arteries and lead to them getting narrowed. This phenomenon is called atherosclerosis and can result in a heart attack or a stroke. The image below
demonstrates atherosclerosis.

Atherosclerosis

Lowering high blood cholesterol levels

There are a number of ways blood cholesterol can be reduced. The aim of reduction in cholesterol levels however should be clear – to lower the bad cholesterol levels i.e. lower LDL and to maintain a high good cholesterol level i.e. increase HDL. Levels in the blood can be determined by a simple blood test, which is ideally performed first thing in
the morning after an overnight fast (fasting cholesterol levels). Lifestyle modifications and pharmacological therapies are the best way to achieve the required targets.

1. Lifestyle modification

This is probably the most important step in lowering high cholesterol levels. A lot of the fat content in the blood comes from consumption of foods that are high in saturated fats such as fried foods, crisps, cakes, cookies etc. Cutting down on these can reduce cholesterol levels significantly, and should be the first step taken towards reducing cholesterol levels.

More recently a lot of emphasis is being placed on trans-fats. It is essential that there be no trans-fats in the diet if one is looking to reduce their cholesterol levels.

Below is a list of foods that will help reduce cholesterol levels –

List of Foods that will help reduce cholesterol levels

  • Fresh fruit
  • Fresh vegetables
  • Whole grain foods like wheat and oats
  • High fibre diet – Bran, oatmeal
  • Lean meat
  • Oil fish – Salmon, Mackerel, Trout, Sardines, Tuna, Halibut
  • Poultry
  • Nuts – Walnut, Almonds
  • Olive oil
  • Plant sterols – These are now a part of many ‘low fat’ spreads

The next step to be carried out with dietary modifications is weight loss. Starting a structured exercise plan (consult with your doctor first) can enable patients to lose weight healthily and efficiently, if practised along with a strict diet. It is recommended that one gets at least 30 minutes of exercise every day.

Another important step to reduce blood cholesterol levels is to stop smoking.

2. Pharmacological treatment

If lifestyle modifications fail to reduce serum cholesterol levels, pharmacological treatments are available that will help. Amongst all the drugs that are used, statins are probably the most popular. They are safe and effective, and have been shown in numerous trials to reduce serum LDL levels, which have a big impact on cardiovascular disease prevalence.

Reduction seen in LDL levels with different statins

The commonly used statins in clinical practice include Simvastatin, Pravastatin, Atorvastatin and Rosuvastatin.

Statins act by inhibiting a key enzyme that is involved in cholesterol synthesis called HMG CoA reductase. They are usually taken at night as this is when cholesterol synthesis is at its maximum. They effectively reduce LDL levels up to 60% and elevate HDL levels as well.

In addition, statins also have certain pleiotropic effects, which include its anti-inflammatory properties and its capability in improving endothelial progenitor cell function. All these have a positive effect on reducing future incidence of cardiovascular disease.

Unfortunately, statins do have a few side effects which can include abnormal liver function tests and muscle inflammation. These are closely monitored anyway and if occur may require stopping of treatment.

There are other treatments that can help reduce cholesterol and triglyceride levels. These include fibrates, nicotinic acid and orlistat, which helps prevent absorption of fats from the intestine.

Conclusion

Cholesterol is an essential component of the blood stream, and is required for a variety of normal functions. However, high cholesterol levels, particularly LDL cholesterol can have detrimental effects and increase a person’s risk of developing heart disease or stroke.

Lowering cholesterol levels can be easily achieved through dietary and lifestyle modifications, and if necessary, drug therapy.