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Cholesterol: Your questions answered

Cholesterol: Your questions answered

Everyday foods can be the best medicine for people with high cholesterol.

Cholesterol is a waxy substance made in the liver. It has various useful functions; it’s a component of cell membranes, sex hormones, vitamin D and bile, which digests fats. There are two types of cholesterol – the good and the bad. Our liver processes most of the cholesterol in our bodies, but when we eat foods high in saturated fat, our liver can’t cope so the cholesterol is returned to the bloodstream. Too much cholesterol in the bloodstream can cause fatty deposits to build up, narrowing the arteries and eventually leading to heart disease and stroke. One in 12 adult New Zealanders currently take medication for high cholesterol. Many more have high cholesterol but are not medicated or have not yet been diagnosed.

Cardiovascular disease (CVD) is the leading cause of death in New Zealand. The risk factors for CVD, heart attack and stroke are well established, and having high cholesterol is one such risk. The only way to find out if you have high cholesterol is to have a blood test.

Changing what you eat has an enormous impact on blood cholesterol. Professor David Jenkins and a team of researchers at the University of Toronto developed the Portfolio diet, which achieved a reduction in cholesterol of more than 2% – a similar result to using cholesterol-lowering medication. The Portfolio diet is based on adding certain cholesterol-lowering foods to a healthy base diet low in saturated fat. These foods are:

  • soy (such as soy milk and tofu)
  • plant sterols (found in margarine)
  • almonds
  • soluble fibre (found in oats, barley and eggplant)

The great news is these foods also fight other heart-disease risk factors and have much in common with cancer-fighting foods, and those recommended for good health.

How high is too high?

Ideally, your HDL (good) cholesterol will be over 1.0mmol/L or above and LDL (bad) cholesterol less than 2.0mmol/L, with total cholesterol less than 4mmol/L*. The ratio of total cholesterol to HDL cholesterol is also used as a good indicator of risk, and the ideal is 4.0mmol/L or less.

*mmol/L (millimoles per litre) is the standard unit of measurement for blood cholesterol.

What’s the difference between good and bad cholesterol?

LDL (which stands for low-density lipoprotein) is the bad type. It deposits cholesterol onto blood vessel walls where it contributes to the damaging process of atherosclerosis (hardening of the arteries). HDL (high-density lipoprotein) is the good type. It carries cholesterol away from the blood vessels back to the liver. It’s easy to remember which is which: just think of H for ‘healthy’!

Who is at risk of high cholesterol?

Being male, being older and having a family history of CVD increases your risk, but you can’t do much about these. Lifestyle change is where you can make a big difference. Besides lowering your blood cholesterol, you can also reduce your risk by giving up smoking, maintaining a healthy blood pressure and healthy weight, looking after your blood sugar levels and being active. Because men have a higher risk, women can forget that it affects them, too. In fact, more than seven women die from heart disease every day in New Zealand.

I’ve just learnt I have high cholesterol. What now?

Healthy living is paramount. A dietitian or qualified nutritionist can give a personalised diet plan and ongoing motivation. Have a follow-up blood test 6-8 weeks after you change your diet to see how well you’re doing. Success is a great motivator.

Can I eat eggs and prawns?

Yes! Although both contain cholesterol, cholesterol in food is not a major determinant of cholesterol in the blood – saturated fat is much more influential. Cholesterol is found only in animal foods, so making ‘cholesterol-free’ claims on vegetable oils, avocados and other vegetable products is meaningless. If you have high cholesterol, your body may not process cholesterol from food in the same way, so in this case it’s best to limit yourself to three eggs a week and don’t overdo the prawns.

Do I need to cut out all fat?

To lower cholesterol, you should replace saturated fats with ‘good’, unsaturated fats. Switch from butter to a spread with added plant sterols and eat some of this every day. You can cut saturated fat intake further by choosing lean meat, skinless chicken and low-fat dairy products. Limit biscuits, cakes, chocolates and fast foods as these are often high in saturated fat. Check labels and stick to 20g of saturated fat per day, no more. If you need to lose weight, focus on reducing your total kilojoule intake rather than cutting all fats from your diet.

What foods should I eliminate?

Trans fats increase LDL (bad) cholesterol and decrease the HDL (healthy) cholesterol – an effect that increases heart disease risk. You can reduce trans fats by avoiding foods high in saturated fat such as butter, fatty meats, pastries, pies and deep-fried fast food. Also look out for the trans fat content on labels and the term ‘partially hydrogenated’ on ingredients lists.

Can medication lower my cholesterol?

While a heart-friendly eating plan is important, in some cases cholesterol-lowering medication is also needed. The good news is there will be even more benefit if you adopt a healthy diet as well as take your medication. A heart-friendly diet can also tackle many other health risk factors.

How can oats, fibre and psyllium help?

Oats contain a soluble fibre called beta-glucan, which has been proven to lower cholesterol. Studies with psyllium have shown similar results. Psyllium, a plant source of soluble fibre, is available as a supplement, and is added to some breakfast cereals. You will also find soluble fibre in legumes and many vegetables and fruit.

First published: Jan 2009

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