Cholesterol is the new 'bad kid' on the block. Fats, salt and sugar have all taken a beating, and now it's cholesterol's turn. And, just like some of its fellow 'bad kid' nutrients, cholesterol has been somewhat misrepresented – contrary to what some might lead you to believe, it is not an evil to be banished from your life altogether, in fact it's essential to your health. This guide will help you to sort the fact from the fiction and find out exactly what it is, how it can put your health at risk and what you can do to prevent that.
What is HDL and LDL cholesterol?
Having good cholesterol levels is all about balance – too little or too much will affect your health adversely. Cholesterol is moved around the body via two types of proteins: High-density lipoprotein (HDL), usually called 'good cholesterol', although it is actually a protein which combines with cholesterol and transports it to the liver so it can be excreted; and low-density lipoprotein (LDL), the 'bad guy', another misleading term as it performs the important function of moving cholesterol from the liver to other parts of the body where it's needed.
LDL only becomes 'bad' when there's an excess of it, which means there's also an excess of cholesterol being ferried around your body. The result is congestion – a cholesterol traffic jam, if you like – within your arteries.
Rather than being caused by eating too much of cholesterol-laden foods such as eggs, prawns or liver, this congestion is far more likely to be a result of a high saturated-fat intake. "Saturated fats have a more dramatic effect on our cholesterol levels because they raise levels of LDL," says nutritionist Carina Norris. "With more LDL, more cholesterol is carried and deposited around the body instead of being taken to the liver and removed."
Your daily recommended cholesterol allowance
The daily recommended cholesterol allowance is 300mg or less. To put that into perspective, an egg contains 213mg; a 100g piece of beef 70mg; 30g of hard cheese, 19mg. "The recommended amount of saturated fat is 22g or less for women and 27g for men," says Norris. "And foods that are high in sat fat include sausages, butter, hard cheese, cream and other high-fat dairy foods, and a lot of manufactured foods such as ice cream, cakes and biscuits."
How lifestyle affects cholesterol
Along with diet, your lifestyle also has an effect on your cholesterol levels: smoking, lack of exercise and stress all contribute to higher levels. Men tend to suffer with high cholesterol more than women because oestrogen, the female hormone, raises HDL; once through menopause, however, oestrogen levels, along with this effect, diminish.
People with diabetes and those with a family history of heart disease (before age 55 for men and 65 for women), should have their cholesterol levels checked every year. People with diabetes and those with a family history of heart disease are at higher risk of heart disease, so a raised cholesterol level will have a more devastating effect on their health. If you're not in either of these groups, you should still have yours checked once every five years.
Normal cholesterol levels
UK guidelines state that a total cholesterol level under 5mmol/l (200 mg/dL) is ideal; but this figure alone is not enough to assess whether there's a serious problem, which is why it's advisable to have yourself tested by your GP, rather than using a home test.
Ideal healthy levels of LDL are calculated to be under 2.6mmol/l (100mg/dL); and a good HDL figure would be 1.04-1.56mmol/L (40-60mg/dL).
But it's the ratio of LDL to HDL that determines how much cholesterol is deposited in the arteries, causing the damaging hardening and narrowing, and other risk factors such as smoking, and high blood pressure also have to be taken into account for a complete diagnosis.
High cholesterol risks
Narrowed arteries: When your cholesterol balance is upset and there's an excess of LDL cholesterol floating around in your blood stream, it settles on your artery walls, making each 'tunnel' narrowed. Your muscles, brain, organs are all fed oxygen via your arteries and so by closing up those tunnels your entire body is put under stress.
Hardened arteries: This accumulation of cholesterol and other substances can also cause your arteries to harden, which makes blockages more likely.
Amputation, stroke or heart attack: If you have a clot, where blood hardens or coagulates, usually after an injury, it could get stuck in a narrowed, inflexible artery, thereby preventing oxygen from reaching parts of your body. The result could be that a limb suffers a lack of oxygen and needs to be amputated, or if the clot blocks a coronary artery, it could cause heart failure or death.
The to-do list
Lift weights: Cholesterol is used to build muscles so by pumping iron you put it to good use, rather than leaving it to clog up your arteries.
Eat fatty food: But make it unsaturated fatty food. "Eating moderate amounts of 'good fat' foods – avocados, oily fish, nuts and seeds, and olive oil – will help reduce your cholesterol level," says Norris. Read our field guide to food fats for more information about different tyoes of fat.
Cut out saturated fats: Saturated fats should be kept to a minimum: "Instead of butter, use a vegetable-oil based spread; cut fat off meat; drink skimmed milk; and eat cheese only as a treat," says Norris.
Get your heart pumping: Exercise burns fat – and that includes cholesterol. Walk briskly for 30-45 minutes at least three times a week.
Quit smoking: Smoking lowers HDL levels and increases LDL. Read our guide for good reasons to stop smoking - and stay stopped.
Feed on fibre: The rough stuff helps transport bad substances out of your blood stream and it keeps you full for longer, so your calorie intake overall is reduced. "Good sources include oats, beans, wholemeal bread, fruit and vegetables," says Norris.
Cut calories: If you overeat, your liver produces more cholesterol to be transported around the body," says Norris. "Keep your daily calorie intake to a healthy 2000-2500."