Cholesterol is a waxy kind of substance naturally produced by the body and essential for normal body function. Cholesterol is known as a lipid, and forms part of the outer membrane of every body cell, helps to insulate nerve fibers, and to make hormones, the chemical “messengers” of the body.
Contrary to widespread belief, only about 20% of the body’s cholesterol is taken in with food. The remainder is made in the liver. After a meal, dietary cholesterol is absorbed from the intestine and stored in the liver. The liver regulates cholesterol levels in the blood, and can release cholesterol when necessary. Although a certain amount of cholesterol is necessary for our bodies to work properly, too much can cause health problems and be a bad thing.
Confusion arises because cholesterol exists in more than one form in the bloodstream. Since cholesterol is a lipid and does not dissolve in the blood, it is transported around attached to protein of one type or another.
One of the types of cholesterol in the blood is called LDL or low-density lipoprotein (also known as “bad” cholesterol”), and elevated levels are associated with an increased risk of coronary artery disease. LDL lipoprotein deposits cholesterol in the artery walls, causing thickening and hardening of the arteries, together with build up of plaques which gradually narrow the artery, impeding blood flow
The other main form of cholesterol in the bloodstream is HDL or high-density lipoprotein (also known as “good” cholesterol) which helps to prevent arterial plaque build-up by taking cholesterol out of cells, including artery wall cells, and transporting it back to the liver where it can be re-cycled or disposed of.
The third major lipid component of the bloodstream is the collection of triglycerides, fatty acids which also cannot dissolve in the blood. Triglycerides may be combined by the liver with protein to form VDL or very low-density lipoproteins.
When your doctor talks about your cholesterol level he is usually referring to the total concentration of both LDL and HDL cholesterol which gives a general estimate of the risk of developing artery and heart disease – the higher the number, the greater the risk. Blood cholesterol is measured in units called millimoles per litre of blood, often shortened to mmol/L. In the UK it is estimated that 60% of the population have a cholesterol level of 5mmol/L or above, and the suggested or recommended level is 4 or lower.
There is some controversy over what the ideal cholesterol level should be but it is generally reckoned that the lower the better. The situation is slightly more complicated though, by the fact that it is not just the total amount of cholesterol that is important, but more the relative amounts of LDL and HDL.
Too much LDL has a definite adverse effect on your risk for disease, as does too little HDL. Thus the Joint British Societies (a group of UK expert societies) recommend a total cholesterol level of less than 4 mmol/L, together with an LDL cholesterol level of less than 2 mmol/L.
Another way of assessing the risk factor which is considered more accurate by some, is to work out the total cholesterol to HDL cholesterol ratio (total chol/HDL). This is calculated by dividing the total cholesterol by the HDL cholesterol to give a number. A higher ratio indicates a higher risk of heart attack, whereas a lower number indicates a lower risk. High total cholesterol and low HDL increases the ratio and is undesirable, while high HDL levels and low total cholesterol lowers the ratio and is more desirable.
It is worth noting that the UK has highest average figures for cholesterol levels in the world, and there is a strong suggestion that lifestyle factors like high saturated fat in the diet, and lack of exercise, are contributory factors. Whilst cholesterol figures are important, and give an indication of risk, a doctor will also take other factors into account in any given case. Factors to consider include age, gender, any family history of heart disease, smoking, high blood pressure, and diabetes.
It is generally recognised that diet can have a significant effect on cholesterol levels. Foods that contain saturated fat are particularly bad for your cholesterol levels and should be avoided or minimised as much as possible. These include fatty red meats, biscuits, cakes, pastries, butter, and junk foods.
5 Foods that can help lower your cholestorol
To help reduce cholesterol levels you should consider the following 5 foods or classes of foodstuffs which are known to be of benefit:
1. Foods containing a high proportion of fibre such as fresh fruit, vegetables, beans, legumes, pulses, and oatmeal. Fibre, especially soluble fibre, is good for helping the digestive process and for reducing the absorption of cholesterol into the bloodstream. Consuming 5-10 grams of fibre a day is the minimum to aim for. A cup and a half of cooked oatmeal provides about 6 grams of fibre. Mixing oat cereals with fruit and bran is a good way of adding variety whilst keeping up your daily fibre intake. High fiber is also an important factor in foods that burn fat.
2. Oily fish, such as salmon, tuna, sardines, mackerel, halibut, and herring, have been shown to help cholesterol balance, as well as decrease blood pressure, and decrease risk of blood clots. At least two servings per week of oily fish are recommended because of their omega-3 fatty acid content. Omega-3 fatty acids are polyunsaturated fatty acids that help lower triglyceride levels whilst also elevating HDL cholesterol (the “good” cholesterol) levels. Baking or grilling fish is preferable to frying to avoid undue intake of unhealthy fats. Fish oil supplements are an alternative way of getting omega-3s but may be deficient in some other nutrients like selenium.
3. Walnuts, almonds and other nuts and seeds, can be good sources of omega-3 fatty acids and are generally good for you. According to the Food and Drug Administration, eating a handful of nuts a day (42.5 grams), such as hazelnuts, walnuts, pecans, almonds, or pistachio nuts, may reduce your risk of heart disease (so long as the nuts aren’t salted).
4. Olive oil is rich in mono-unsaturated fats, especially oleic acid, and two tablespoons (23 grams) a day may reduce the risk of coronary heart disease. It is of course important that this should replace a similar amount of saturated fat in your diet, otherwise you may not get any benefit and are just adding calories. Regular intake can have favourable effects on cholesterol regulation and LDL cholesterol oxidation. The latter is thought to be particularly beneficial in reducing arterial plaque build-up. In addition to its anti-oxidant properties, olive oil is also anti-inflammatory, anti-thrombotic, and anti-hypertensive.
Olive oil also seems able to displace omega-6 fatty acids, while not having any impact on omega-3 fatty acids, helping to build a more healthy balance between the two. The less processed types of olive oil are thought to give maximum health benefits.
5. Sterols and Stanols are naturally occurring plant substances, that, when taken in fairly substantial amounts, are able to block uptake of cholesterol from the gut. They reduce total and LDL cholesterol but have little effect on HDL cholesterol and triglycerides.
Because they occur in plants, a vegetarian biased diet will provide the maximum benefit. Sterols and stanols are found in good amounts in rice bran, avocados, wheat germ, and extra virgin olive oil, and are also now added to various manufactured foods such as margarine and yoghurts.
The effectiveness of sterols and stanols seems to vary widely from one individual to another, but a recent study of 72 people with slightly raised cholesterol, taking 2 gram a day of sterol in orange juice showed a reduction of LDL cholesterol by about 12% over a period of 8 weeks.
By eating healthily and choosing many foods that can help reduce cholesterol levels you can reduce your risk of developing artery and heart disease, as well as improving your health generally, and all without having to resort to drugs or medicines.