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You’ve heard the term ‘cholesterol’. We have all seen foods and medications advertised on television boasting they will help to reduce your cholesterol levels. But what exactly is cholesterol and why does it need to be low?
Most of the cholesterol in our blood is produced by the body itself. It has an essential role in all cell membranes and how every cell in the body functions. However, people with high cholesterol concentrations in their blood have a higher risk of coronary heart disease than people who have lower levels. The risk is particularly high if you have a high concentration of LDL cholesterol and a low level of HDL cholesterol.
What are LDL and HDL cholesterol?
LDL (low density lipoprotein) cholesterol and HDL (high density lipoprotein) cholesterol transport fats, including cholesterol, around the body.
- LDL is considered the ‘bad’ carrier as it takes cholesterol from the liver via the arteries (the blood vessels carrying blood away from the heart) to be stored in other parts of the body. If there is too much in our arteries it can accumulate in the blood vessel walls and restrict blood flow and even cause a complete blockage. A blockage in the heart causes a heart attack; in the brain, a stroke.
- HDL is considered the ‘good’ carrier as it carries cholesterol away from the blood to the liver, where the cholesterol is metabolised.
How cholesterol levels are measured
Blood cholesterol concentrations can be measured through a simple blood test. It will usually measure total cholesterol, LDL cholesterol and HDL cholesterol, and a ratio of total cholesterol to HDL cholesterol.
Causes and what to do if you have high cholesterol
The main factors likely to increase total blood cholesterol levels (in particular LDL) include a family history of high cholesterol levels, eating too many foods high in saturated fat, being overweight and physically inactive, and high levels of stress.
Unfortunately we can’t change our family history, but we can increase HDL and reduce LDL cholesterol concentrations by being more active, maintaining a healthy weight, eating a healthy diet, reducing stress and not smoking.
Making small changes to everyday eating is a good way to lower blood cholesterol levels. Following the tips below will help you minimise foods high in saturated fats, replacing them with polyunsaturated and monounsaturated fats. You should also include foods high in soluble fibre, which may help lower blood cholesterol, for example fruit, vegetables, oats and legumes (baked beans, lentils, red kidney beans, chickpeas).
- Choose low-fat dairy products such as trim (green top) or reduced-fat (light blue top) milk, low or reduced fat cheeses (including edam and cottage cheese) and low fat yoghurts.
- Choose lean cuts of meat, removing any visible fat from meat and skin from chicken.
- Reduce fat required for cooking by grilling, baking, stir frying in a non-stick pan or microwaving.
- Choose vegetable-based spreads and oils such as olive, canola and sunflower oils.
- Try a few unsalted nuts (such as almonds or walnuts) as a healthy snack.
- Try chopped fruit on breakfast cereal, an extra piece of fruit with lunch and some vegetables with your evening meal as easy ways to eat more fruit and veggies. Porridge and baked beans on toast have good amounts of soluble fibre.
- Some foods are higher in saturated fat than we realise because the fat is hidden in the food. Some examples of these foods are coconut cream, deep-fried foods, potato chips, cakes, biscuits, pies and pastries. So it is best to only eat these foods occasionally.
- Foods rich in soy protein (tofu, soya beans, soy milk) may also contribute to a small cholesterol-lowering effect.
- Some people may also require medication to help lower their cholesterol levels. Contact your doctor for advice on whether medication is necessary for you.
What about Plant Sterols? Will they reduce high cholesterol?
Plant sterols (or phytosterols) are found naturally in very small quantities in a variety of plant foods such as grains, vegetables, fruit, legumes, nuts and seeds. They actively lower cholesterol by partially blocking the absorption of LDL or “bad” cholesterol in the digestive system.
The Australian New Zealand Food Code permits the addition of plant sterols to edible oil spreads, breakfast cereals, milk and yoghurt.
In a recent systematic review by Food Standards Australia New Zealand (FSANZ) (2014) it was concluded that there is a ‘High’ degree of certainty that increased plant sterol intake reduces blood total and LDL cholesterol concentrations. Because of the strong evidence plant sterols are effective in lowering LDL cholesterol, FSANZ approved a health claim
The Health Claim states that 2g of plant sterols daily lowers cholesterol within 4 weeks as part of a healthy diet low in saturated fat. This has been proven in over 40 clinical trials that cholesterol is lowered by up to 9% within 4 weeks. The New Zealand Nutrition Foundation endorses this claim.
For more information on heart health, visit the New Zealand Heart Foundation website.