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Condition - Cholesterol

By Dr Pieris Nicola PhD BSc (Hons) Dip ION

Cholesterol is a waxy, fat-like substance that is a building block for the body’s organs. In particular, it is an important component of the cell membrane. Cholesterol is transported to the body’s cells in the bloodstream. Only about a quarter of the cholesterol in the bloodstream comes from the diet. The rest is manufactured by the liver, which converts dietary fats and cholesterol into the different types of cholesterol found in the body. The type of fat you eat influences blood cholesterol more than the amount of cholesterol you eat. 

Your body needs some cholesterol to function properly. But if you have too much in your blood, it can build up on the walls of the arteries. This build up is called plaque, and may lead to the condition “atherosclerosis.” Plaque can narrow the arteries and make it harder for blood to flow. It can even block the flow of blood. Plaque increases the risk of cardiovascular diseases such as heart disease and stroke. 

There are two main types of cholesterol in the body, often called LDL (low-density lipoprotein) and HDL (high-density lipoprotein). High levels of LDL cholesterol can lead to atherosclerosis, and for this reason LDL cholesterol has been labelled “bad” cholesterol. HDL cholesterol, on the other hand, is associated with a reduced risk of atherosclerosis, and is therefore often referred to as “good” cholesterol. LDL cholesterol levels should be kept as low as possible. If your doctor tells you that you have high cholesterol, it means that your “bad” cholesterol is too high. Your risk of heart disease and stroke is increased if you have high levels of LDL cholesterol and low levels of HDL cholesterol. 

You may also have heard “triglycerides” mentioned in discussions regarding cholesterol. These make up most of the fat you eat and they travel through the bloodstream. Your body needs triglycerides, but it is best to keep levels low. 

How HDL helps

HDL carries excess cholesterol from artery walls and delivers it to the liver for processing and removal from your body. But scientists have discovered that HDL does more than that. Research shows that HDL has antioxidant activity that can help protect LDL cholesterol from free radicals. This is important because a key step in atherosclerosis is when LDL cholesterol in the wall of the artery is attacked by oxygen free radicals, turning it into oxidised LDL cholesterol, which is the stuff that is actually responsible for arterial damage. HDL also has anti-inflammatory activity, which helps to dampen the inflammation triggered by oxidised LDL, plus the ability to reduce the formation of artery blocking clots, as well as accelerating the healing process that dissolves existing clots. 

Low HDL levels are associated with a greater risk of heart attacks, whilst high HDL levels can reduce the risk of heart attacks and stroke whatever the LDL cholesterol levels. HDL cholesterol appears to be a better predictor of the risk of ischaemic stroke than LDL cholesterol levels, particularly in those older than 75. The Massachusetts Male Aging Study found that 16% of men with low HDL cholesterol levels had erectile dysfunction, but none with the highest levels had the problem. This is because normal erections also depend on healthy arteries that produce healthy amounts of nitric oxide, an important molecule that helps relax constricted blood vessels and ease blood flow. Furthermore, several studies suggest that high HDL cholesterol levels are linked to “exceptional longevity,” as well as preserved cognitive function in old age. 

Checking cholesterol levels

Cholesterol levels can be measured by a simple blood test, which will tell you your total cholesterol, LDL cholesterol, HDL cholesterol, and triglyceride levels. Frequently, your GP will provide you with a total cholesterol reading which should be below 5 mmol/L to be in the healthy range. 

There is no “normal” level for HDL cholesterol - the higher the level, the better. But targets are important. The National Cholesterol Education Programme and the American Diabetes Association recommends HDL levels of at least 40 mg/dL (1.03 mmol/L in men) and 50 mg/dL (1.29 mmol/L in women). HDL cholesterol levels often get overlooked because it is easier to reduce LDL cholesterol than to increase HDL cholesterol. But the good news is that simple dietary and lifestyle changes can help increase HDL levels. 

What is the medical treatment for high cholesterol?

The initial method of treatment will usually involve changing your diet and increasing physical activity. If after a few months cholesterol levels are still high, you will likely be advised to take cholesterol-lowering medication. There are different kinds of medicines to treat high cholesterol levels, and they work in different ways. Statins are used the most because they can lower LDL cholesterol. However, statins also increase the risk of liver inflammation (hepatitis), and more recently, statins have also been associated with muscle weakness and rhabdomyolysis (breakdown of muscle fibres). Other kinds of cholesterol-lowering medicines include bile acid binders, cholesterol absorption inhibitors, and fibrates

Nutritional considerations

  • Garlic. Sulfur-containing compounds, including S-allyl cysteine and ajoene, have been found to inhibit the key enzyme in cholesterol synthesis called HMG-CoA reductase. Garlic is a good source of S-allyl cysteine and ajoene.
  • Soy isoflavones are a group of phytonutrients that may help to support normal blood cholesterol levels.
  • Phytosterols (plant sterols) are substances found in plants that are chemically similar to cholesterol. However, unlike cholesterol, they are poorly absorbed from the gut. Phytosterols interfere with the absorption of cholesterol from the digestive tract. Interfering with intestinal cholesterol absorption may help maintain LDL cholesterol levels within a normal healthy range.
  • Fish oil. Long-chain omega-3 fatty acids (including EPA and DHA) can help to reduce LDL cholesterol and triglyceride (blood fat) levels, and may raise HDL levels. Studies have also associated long-chain omega-3 fatty acids with reduced blood pressure, reduced inflammation, improved heart rhythm stability, and reduced risk of developing blood clots and sudden cardiac death. Fish oil is an excellent source of long-chain omega-3 fatty acids.
  • Magnesium may help support LDL and HDL levels within a normal range.
  • Chromium.  The results of some clinical trials suggest that chromium may help support healthy HDL levels.
  • Vitamin E.  A chemical reaction, analogous to rusting, called oxidation, damages LDL cholesterol. Oxygen free radicals are responsible for the oxidation of LDL. A substantial body of evidence suggests that oxidised LDL cholesterol has the propensity to set-off the artery-clogging process of atherosclerosis. Therefore, even if cholesterol levels remain unchanged, protecting LDL from oxidation could help to reduce the risk of heart disease. Vitamin E, the major fat-soluble antioxidant present in LDL, is a free radical scavenger that may help protect LDL against oxidation.
  • Coenzyme Q10 (CoQ10).  This is a vitamin-like substance made by the liver and found in plants and meats. It has antioxidant properties and produces ATP to power cellular reactions. CoQ10 is also vital for cardiac function. Statins are cholesterol-lowering medicines, which inhibit HMG-CoA reductase. Inhibition of this enzyme may also inhibit CoQ10 synthesis. Statin-induced CoQ10 depletion is well documented in human studies.
  • Cinnamon may help to support normal healthy triglyceride, LDL cholesterol and total cholesterol levels.
  • Green tea is a rich source of nutrients called catechins. EGCG (epigallocatechin gallate) D is the major catechin present in green tea. A recent study, published in the Journal of biochemical and molecular toxicology, showed that consumption of EGCG is associated with a favourable impact on serum HDL, LDL and total cholesterol levels. Green tea catechins may interfere with the intestinal absorption of dietary and biliary cholesterol, as well as possibly impacting cholesterol synthesis. Catechins may also reduce cholesterol oxidation through their free radical-scavenging actions.
  • Red yeast rice is rice fermented with a species of yeast, called Monascus purpureus, which gives it a red colour. Red yeast rice has a long history of use, and is a dietary staple in many Asian countries, where it is used to naturally colour various dishes. Red yeast rice may help to support healthy LDL cholesterol, total cholesterol, and triglyceride levels. 

Dietary recommendations

Improving cholesterol levels through diet requires adding foods that help lower LDL, and cutting back on the foods that increase LDL. Adding several foods that help combat high cholesterol in various ways is better than focusing on one or two foods only.  

Cholesterol lowering foods

  • Nuts. Two ounces of nuts a day can help lower LDL cholesterol, in the order of 5%. Nuts have additional heart-protecting nutrients. Of particular benefit are walnuts. Walnuts are a good source of alpha-linolenic acid, a plant omega-3 fatty acid. According to the results of a study from Japan, published in the European Journal of Clinical Nutrition, a diet rich in walnuts increases levels of alpha-linolenic acid, and this increase appears to be responsible for their LDL cholesterol-lowering effects.
  • Garlic. Garlic may help to support normal plasma cholesterol concentrations.
  • Fibre. There are two main types of fibre: soluble and insoluble. Only soluble fibre has a favourable impact on LDL cholesterol levels. There are a number of possible ways it does this, including blocking the absorption of fat and cholesterol into the blood stream, preventing the re-absorption of bile acids in the small intestine, and reducing after-meal glucose and insulin levels. A meta-analysis that combined the results of 67 controlled trials found that even a modest 10 grams per day increase in soluble fibre intake resulted in reductions in LDL cholesterol averaging 22 mg/dL (0.57 mmol/L) and reductions in total cholesterol averaging 17 mg/dL (0.45 mmol/L). On a cholesterol lowering diet, you should aim for at least 5-10 grams of soluble fibre per day, and ideally 10-25 grams.

Good sources of soluble fibre include:

  • Fruits & Vegetables. Of particular benefit are apples, grapes, strawberries and citrus fruits: these fruits are rich in pectin, a type of soluble fibre that lowers LDL cholesterol. Eggplant (aubergine) and okra are low-calorie vegetables that are also good sources of soluble fibre. Including a variety of colourful fruits and vegetables in your daily eating routine will also help to increase your intake of vitamins, minerals, fibre and phytochemicals (including antioxidants).
  • Beans. There are a number to choose from including navy and kidney beans, lentils, garbanzos, black-eyed peas etc.
  • Oats.
  • Barley and other whole grains.
  • Soy. Soybeans and foods made from fermented soy including tofu, tempeh and miso, as well as  soy nuts may help lower LDL cholesterol.

Beneficial fats and oils.

  • Fatty fish. Eating oily fish two to three times a week can help lower LDL cholesterol and triglyceride levels, and improve HDL levels. The highest levels of omega-3 fatty acids are in salmon, mackerel, lake trout, herring, sardines, albacore tuna and halibut. Avoid fried fish. Poach or grill fish to limit intake of other fats. If you are  vegetarian, enjoy flaxseeds and walnuts (and their oils), which are good sources of alpha-linolenic acid.
  • Monounsaturated fats are mostly present in oils such as olive and canola oil, avocados, and in most nuts, and seeds such as pumpkin and sesame seed. Monounsaturated fats can decrease total cholesterol levels while maintaining and possibly elevating HDL levels. Olive oil is more than just a monounsaturated fat. It is  a source of phenolic antioxidants which have been shown to reduce the oxidation of LDL cholesterol.  Extra-virgin olive oil contains an abundance of these phenolic antioxidants. Use it to sauté vegetables, stir fry, marinade, in salad dressings, and as a healthy substitute for butter – try dipping bread in extra-virgin olive oil instead of slathering it with butter or margarine. Oils are calorie dense so avoid excessive intakes.

Season your food with garlic, onions and herbs.

Become familiar with the Nutrition Information Panel on packaged foods, which lists information on the amount of calories, saturated fat, trans fat, and cholesterol per serving. 

Reducing the bad:

  • Omega-6 polyunsaturated fatty acids are found in corn, safflower, soybean and sunflower oil. Omega-6 fatty acids are also important for health. However, a high intake of these fats has been associated with abdominal weight gain (the apple shape), which is a risk factor for cardiovascular disease. And these fats appear to have little effects on plasma cholesterol concentrations, and may even reduce HDL levels.
  • Harmful fats. Reducing the consumption of saturated fats and trans fatty acids is a major step in managing cholesterol levels through diet.
  • Saturated fats raise your total blood cholesterol more than any other types of fat or cholesterol, and they do this by elevating harmful LDL cholesterol.  Saturated fats are found predominately in animal products, including meat, seafood, poultry with skin, and full-fat dairy products (milk, cheese, and ice cream). Several studies have identified a direct association between the amounts of dietary saturated fat consumed and total cholesterol concentrations. The saturated fats in butter and other dairy products directly increase LDL cholesterol. The saturated fat in beef fat is not quite as strong at increasing LDL, and those in chocolate and cocoa butter have an even smaller effect. Studies suggest that replacing saturated fats with the beneficial fats (listed above) improves the ratio of LDL to HDL. Limit your intake of saturated fats by reducing the consumption of red meat and full-fat dairy products. Choose the leanest cuts of pork, veal and beef, which are comparable to chicken in calories and fat as well as their effect on LDL and HDL levels. Also, trim any visible fat, and favour grass-fed meat, which is higher in omega-3 fats.  Replace some of the red meat with beans, nuts, poultry and fish, and switch from full-fat dairy products to lower fat versions.
  • Trans fats. Polyunsaturated fats are often hydrogenated to harden their appearance (e.g. margarine). Hydrogenation results in the production of trans fatty acids. Research has shown that trans fats are worse for cholesterol levels than saturated fats, because they raise LDL and lower HDL levels. They also increase the amount of inflammation in the body, have harmful effects on the linings of the arteries, and may even increase the risk for type 2 diabetes. Hydrogenated fats are used in stick margarine and in many fast foods and baked goods, including most commercially produced white breads. Fried foods in restaurants can also be a source. If you need something spreadable, use very small amounts of butter (preferably made from the milk of grass-fed cows) or soft margarine that is trans free and low in saturated fat.
  • Cholesterol. Animal-based products contain cholesterol. High amounts occur in meat, dairy products, egg yolks, liver, and shellfish such as shrimp and lobster. Scientific studies have shown only a weak relationship between the amount of cholesterol a person consumes and his or her blood cholesterol levels. For most people, the amount of cholesterol eaten has very little impact on blood cholesterol levels. However, for some people, known as “responders,” the amount of cholesterol eaten has a strong influence on blood cholesterol levels.  With responders, avoiding cholesterol-rich foods can have a substantial effect on blood cholesterol levels. There appears to be no way to identify responders from non-responders, other than by trial and error. The relationship between eggs and cholesterol deserves further mention. It appears that eating eggs has little effect on LDL levels. A study, which looked at the egg eating habits of approximately 120,000 men and women, found no connection between egg consumption and heart disease or stroke. Eggs are low in saturated fat and contain many other healthful nutrients including protein, polyunsaturated fats, B vitamins, and vitamin D.
  • Refined carbohydrates. A diet high in refined carbohydrates may reduce HDL levels and raise triglyceride levels. Favour whole grains, beans and vegetables over starchy food such as pasta, white flour products and potatoes. Simple carbohydrates (sugars) should also be reduced. Sugars include sucrose (source of most dietary sugar) and fructose (found in fruits and vegetables). High levels of sugar consumption, whether fructose or sucrose, have been associated with higher triglyceride levels and lower HDL levels. Avoid sweetened beverages and fruit juice.
  • Beverages. Although coffee contains phenols, which help prevent oxidation of LDL cholesterol, unfiltered coffee brews (such as Scandinavian boiled, Turkish, and cafetière coffee) contain a compound called cafestol, which may increase cholesterol and triglyceride levels. Filtered coffee does not contain cafestol

Lifestyle recommendations

  • Exercise. Try to make exercise a consistent part of your life by finding an activity that is right for you. Research has shown that moderate to vigorous aerobic exercises can boost HDL by 5% to 10%, and can lower triglyceride levels. Other benefits include a reduction in blood pressure, body fat, blood sugar, mental stress, and a reduced risk of blood clots. These protective effects can occur with as little as one mile of walking or jogging per day. Try to aim for five 30-minute sessions of physical activity per week, but the more you do, the better. If you are sedentary, try to incorporate any kind of physical activity in your daily life. Gardening, housework, walking the dog and even climbing the stairs are examples of how physical activity can be incorporated into your daily routine. Resistance (strength) training also helps to reduce LDL levels. Patients with heart disease should consult their doctor before starting a physical activity program.
  • Cigarette smoking.  Both male and female cigarette smokers have lower HDL levels. Additionally, life-time non-smoking individuals frequently exposed to large doses of second-hand tobacco smoke exhibit low levels of HDL, which are similar to those of smokers, both of which are significantly lower than the HDL levels of non-smokers. Fortunately, HDL levels rise by as much as 15% to 20% after you give up smoking.
  • Weight. Obesity is linked to low HDL levels. If you are overweight or obese, you can increase your HDL levels by approximately 1 mg/dL for every seven pounds lost. But any amount of weight loss will help.

Stress reduction. Stress is associated with negative effects on the heart. Practise relaxation techniques including yoga, meditation, or breathing exercises, prioritise your tasks, and stay positive.

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