What is cholesterol?

Cholesterol is a fatty substance found throughout the body. It is essential for synthesising vitamin D, stress hormones and sex hormones. Cholesterol is also an important part of bile, required for digestion of fats, and is essential for healthy cell membranes.

Where does cholesterol come from?

The liver manufactures most cholesterol, although a small amount is obtained from our diet. Cholesterol circulates around the body in the blood stream attached to specific proteins called lipoproteins.

There are two types of lipoproteins; HDL and LDL.

High density lipoprotein (HDL) contains high amounts of protein and a small amount of cholesterol. HDL cholesterol is considered “good” cholesterol because it helps remove LDL cholesterol from the arteries. Experts believe HDL acts as a scavenger, carrying LDL cholesterol away from the arteries and back to the liver, where it is broken down and passed from the body. One-fourth to one-third of blood cholesterol is carried by HDL. A healthy level of HDL cholesterol may also protect against heart attack and stroke, while low levels of HDL cholesterol have been shown to increase the risk of heart disease.

Low density lipoprotein (LDL) contains high amounts of cholesterol and small amount of protein. LDL cholesterol is considered the “bad” cholesterol because it contributes to plaque, a thick, hard deposit that can clog arteries and make them less flexible. This condition is known as atherosclerosis. If a clot forms and blocks a narrowed artery, a heart attack or stroke can result. Another condition called peripheral artery disease can develop when plaque buildup narrows an artery supplying blood to the legs.

HDL and LDL should be in the ration 2:1 in favour of HDL.

High Cholesterol occurs when this balance is upset in favour of LDL.

What is considered high cholesterol?

Ideal level - Less than 5.0mmol/L

Borderline - Between 5 – 6.4mmol/L

Moderately high - Between 6.5 – 7.8mmol/L

Very high - Above 7.8mmol/L


Factors that influence high cholesterol

  • Family history of heart disease or high cholesterol
  • Smoking
  • Poor diet low in fibre or vegetables
  • Diabetes
  • Sedentary lifestyle
  • High blood pressure
  • Diet high in trans fats (found in deep fried foods, processed foods)
  • Obesity
  • Stress
  • Low gut bacteria

What is harmful about high cholesterol?

Cholesterol is useful to the body and is essential to many of its processes. However, if the body is unable to clear away cholesterol quick enough, cholesterol can build up in the arteries. Cholesterol also acts as a ‘fire engine’ to a fire, thus when damage occurs to an artery (eg through stress, high blood pressure, smoking etc), cholesterol goes to the area to assist in the repair process. Unfortunately, if the damage continues to occur, more and more cholesterol is taken to the area of repair, resulting in a build up.

Foods to limit

These foods have been shown to increase levels of LDL cholesterol and should be kept to a minimum.

  • Refined Carbs: Avoid foods high in fast releasing sugars such as white bread, confectionary, cakes and biscuits as these can upset insulin regulation and lead to obesity. A low sugar diet has been shown to lower cholesterol.
  • Saturated Fats: Limit foods including hard cheeses,full fat dairy products, cream, fatty meats (lamb,pork, sausages and burgers) and cakes and biscuitsthat contain harmful saturated fats which can raise cholesterol levels. Hydrogenated fats and oils should also be avoided which are in things like take away meals and fried foods.
  • Red Meat: You don’t need to avoid red meat completely but be aware of portion sizes (a portion should roughly be the size of your palm) and limit to no more than twice a week.  Red meat has been linked with an increased risk of bowel cancer so limit to one or two small serves per week and avoid processed meats (salami, chorizo) and burnt meats (don't overcook on the bbq).
  • Stimulants: Tea, coffee, sugary carbonated drinks and alcohol should be limited because they stimulate the stress response. However one glass of red wine a day can have a cholesterol-lowering effect.

Foods to increase

 Complex Carbs: Complex carbohydrates release their energy slowly and contain dietary fibre which binds to cholesterol and helps reduce blood levels. Oats and bran are particularly beneficial for cholesterol lowering-effects.

 Fibre: Lentils and pulses are also good sources of fibre which may help lower cholesterol.

 Fruit & Veg: Fruit and vegetables are not only packed with fibre but they also contain vitamin C, vitamin E and Beta Carotene which have antioxidant properties and help reduce high cholesterol risk. Choose brightly coloured varieties including peppers, berries, kale and squash. There is also evidence that garlic has cholesterol-lowering properties due to its antioxidant levels.

 Essential Fats: Healthy fats from nuts, seeds and oily fish such as salmon, trout, mackerel and herring are beneficial and may actually help reduce high cholesterol.

 Lean Protein: Fish, skinless chicken and turkey are all good sources of protein that contain less of the harmful, saturated fats which raise cholesterol levels.