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pg089-92 HEALTH
- 1. MAY 2013 ExpatriateLifestyle | 89 health&wellness: cholesterol health&wellness: cholesterol Mention cholesterol and the immediate reaction of most people would be ‘bad’. But there are a lot of other facts to be gleaned about this organic molecule and its role in our bodies WORDS MARIA MASOOD GOOD CHOLESTEROL BAD CHOLESTEROL
- 2. 90 | ExpatriatELifEstyLE MAY 2013 heAlth&wellness: cholesterol CHOLEstErOL is a fatty sUBstaNCE prODUCED iN OUr BODy, aND is EssENtiaL iN rEpairiNG aND fOrMiNG NEW CELLs, HOrMONaL prODUCtiON, fOOD DifEstiON, BiLE prODUCtiON aND MOrE A lthough ‘cholesterol’ normally seems like a negative word because of the bad reputation surrounding it, a certain amount of it is essential to perform several important functions in the body. Cholesterol is a fatty substance that is produced in our body, and is essential in repairing and forming new cells, hormonal production, food digestion, bile production and more. It is also important in keeping the cell membranes resistant to changes in temperatures as well as the production of vitamin D. However, too much of anything is not very good, and that’s just the case when it comes to the amount of cholesterol content in our body. About 80% of cholesterol is produced by the liver while the rest comes from the food that we eat. Major dietary sources of cholesterol include cheese, egg yolks, poultry, fish and shrimps. In the United Stataes, the typical daily dietary intake of additional cholesterol is 200 to 300mg. However, cholesterol that is ingested or taken in through food actually has very little effect on the concentration of cholesterol in a person’s bloodstream. An interesting phenomenon about cholesterol is that it is insoluble in blood (as it is not water soluble), and so it requires the help of certain molecules called lipoproteins to travel through the bloodstream. The size of these lipoproteins determines how much cholesterol is deposited in the blood vessels. Imagine yourself leading a blind friend through a pathway. That’s just what the lipoproteins do to the cholesterol in our bodies: they circulate through the bloodstream and transport the cholesterol to and from the cells. There are two types of lipoproteins classified on the basis of their density: Low Density Lipoproteins (LDL) and High Density Lipoproteins (HDL). LDLs have low protein content and carry more cholesterol. They are also referred to as Bad Cholesterol since they cause considerable problems. As a result, it is required that a low level of LDL is maintained for proper functioning of the arteries. While they travel through the bloodstream, they keep losing the cholesterol cells, and since they are less dense molecules, they can travel easily through the arteries and accumulate cholesterol there. What these LDLs do is direct the cholesterol towards the arteries where it can build up as plaque, which may result in a condition called atherosclerosis. Atherosclerosis is a condition where plaque formed from fatty substances, cholesterol, cellular waste, calcium and fibrin gets accumulated in the inner walls of the arteries that typically go to the heart and the brain. This results in thickening and hardening of the arteries. Now, if the walls of the arteries are thickened, they get very narrow and obstruct the blood flow in the arteries, decreasing the oxygen supply to the heart and the brain. This encourages bleeding in the inner walls of the arteries, and blood clots on the plaque. This can get worse, and may eventually result in a heart attack or a stroke. Not all cholesterol is bad though. On the other side of the spectrum we have HDLs, also known as Good Cholesterol for all the right reasons. About 20 to 30% of cholesterol is carried through the HDLs. HDLs have high protein content and are more dense molecules. They cannot pass easily through the arteries, and therefore they direct the cholesterol away from the arteries and towards the liver, where it can be disposed or reprocessed as required. The liver then excretes the cholesterol into the digestive track, and about 50% of this excreted cholesterol is reabsorbed back into the blood stream. The HDLs prevent the accumulation of cholesterol in the inner artery walls and act as scavengers which smoothly sweep away or clean the inner artery walls, thereby maintaining its proper diameter. They activate the inner most layer of the arteries called the endothelium, and prevent inflammation. The amount of cholesterol produced or absorbed in the body hugely depends on our genes. Familia Hypercholesterolemia, which is the most common type of
- 3. MAY 2013 ExpatriatELifEstyLE | 91 heAlth&wellness: cholesterol an inherited disorder, comes about due to a mutation in the genes. Here, the amount of bad cholesterol is very high. According to recent studies, about 1 in every 500 individuals has familia hypercholesterolemia. These individuals are at a greater risk of developing coronary artery diseases. It is required that a low amount of LDL and a relatively higher amount of HDL are maintained for a proper functioning of the body. It has been found that women have higher HDL content than men. A good amount of HDL is greater than 60 milligrams/deciliter, and one should make sure it does not fall below 40 milligrams/deciliter as it may have serious consequences. A cholesterol test that determines the LDL and HDL levels is also recommended every five years. One way to boost your HDL level is to exercise regularly. This increases the size of the lipoproteins and makes it too dense to pass through the narrow blood vessels, thereby directing it towards other organs such as the liver. Exercise also helps you to lose weight, which in turn reduces the LDL content in the blood. The more you work out, the more LDLs the body drives out. Although exercise in any way is good, studies show that vigorous or high intensity exercise is better than moderate exercise in terms of maintaining proper cholesterol content. For instance, aerobic exercises for about 30 to 60 minutes on most of the weekdays have been proven to increase the HDL content in the body. Minimizing the fat storage inside the abdominal cavity is especially important, in addition to minimizing your total body fat. If you are a smoker, another great way to increase your HDL level is to quit smoking. Smoking can have a very bad effect on the overall cholesterol level of the body. Nicotine increases the amount of bad cholesterol and decreases the amount of good cholesterol in the bloodstream. Smoking, besides affecting your blood circulation, can also result in a cholesterol-related condition called Beurger’s Disease, where the circulation is affected to such a degree that blood is no longer able to reach the fingers and toes. This can result in the fingers and toes becoming gangrenous, and they may eventually need to be amputated. Nicotine can also lead to constriction of the artery walls, thereby resulting in the heart pumping the blood through the arteries with greater difficulty. This condition is called hypertension, and here the blood pressure rises along with an increase in the cholesterol level. Therefore, giving up smoking can have a profoundly positive effect on your overall health when it comes to cholesterol. Another way to increase your HDL content is to take HDL boosting drugs, which are prescribed by the doctor in the case of individuals who have extremely low HDL levels (less than 40 milligrams /deciliter). Otherwise, eating food rich in fiber like grains, oats, bran, onions, and omega-3 fatty acids like flax oil, fish and soy can prove to be very beneficial in increasing the HDL levels in the bloodstream. If a person has a very low amount of LDL, but their HDL Levels are not high enough, then they are still exposed to an increased risk of coronary diseases. Therefore, the more HDLs in the bloodstream, the better it is for the overall proper functioning of the body.
- 4. 92 | ExpatriateLifestyle MAY 2013 health&wellness: cholesterol What are the dietary sources of good cholesterol? The sort of fat, which is considered as “good fat”, is called essential fatty acids because these fatty acids cannot be synthesized by the human body. The essential fatty acids are omega-3 and omega-6 fatty acids. Omega-3 fat is widely found in oily fish, such as salmon, herring, mackerel and sardine. Good sources of omega-6 fats are vegetable oils, such as soya bean, canola and sunflower oils. Therefore it is recommended to consume at least 2 servings of oily fish per week and to use vegetable oils as cooking oil. Another type of “good fat” is polyunsaturated fatty acid (PUFA). Adequate consumption of PUFA can actually reduce total cholesterol in the body and, to some extent, increase the “good” HDL cholesterol in the body. For the record, the “bad” cholesterol in the body is LDL, and both of these LDL and HDL cholesterols are produced in the body. The modulation of these 2 cholesterols is determined by the type of fat consumed. What are the dietary sources of bad cholesterol? The types of fat that should be avoided are dietary cholesterol, saturated fat and trans fat. It is a well-known fact that increased dietary cholesterol intake leads to higher risk of coronary heart disease (CHD). Saturated fat can increase cholesterol level in the body, hence increases CHD risk. Trans-fat has strong association to CHD and was found to have increased LDL cholesterol level while reducing HDL cholesterol level in the body. In fact, trans-fat poses greater CHD risk compared to cholesterol and saturated fat. Cholesterol-rich food includes fatty cuts of meat, seafood (excluding fish), egg yolks, fish roes, and organ meats. Saturated fat is typically found in coconut oil, coconut milk, palm oil, and animal fat, while trans-fat comes from hydrogenised fats such as margarines and shortening including foods prepared using hydrogenised fats. Is there a risk if a person has a very low LDL level, but does not have high enough HDL Levels? HDL cholesterol is not an independent contributing factor toward reducing CHD risk although higher HDL cholesterol level is shown to reduce CHD. However LDL cholesterol has a linear association to CHD risk—the higher the LDL level, the higher the CHD risk. Thus very low LDL cholesterol level will pose no risk, if not, significantly reduces CHD risk. How much daily intake of cholesterol is considered ‘bad’? Based on the Malaysian Dietary Guidelines, dietary cholesterol intake should be limited to 300 mg a day. That is an equivalent of 2 pieces of egg or 9 pieces of chicken wing or 9 glasses of fresh cow’s milk. What are the other vital organs (besides the heart and the brain) that bad cholesterol affects? It can also affect the upper and lower limbs, and in extreme cases, the eyes. If someone has high LDL level, what are the other ways to control cholesterol? Having high HDL level is not an independent indicator for a lower CHD risk. Besides diet control, HDL can be increased by regular exercise, reducing body weight, quit smoking, and increase dietary intake of soluble fiber, commonly found in oat, legumes, nuts, fruits, and root vegetables. As a matter of fact, adequate consumption of dietary fiber can actually lower cholesterol level in the body. Oat bran, for example, was shown to reduce LDL cholesterol level, while beta-glucan was proven to help reduce cholesterol. Weight control is also important in controlling cholesterol. How can we prevent cholesterol build up from an early age through diet? Personally, starting young is key towards good health later in life. In the aspect of preventing cholesterol build-up, diet control is about making healthy food choices, healthy cooking methods, and healthy eating habit. The important thing is to limit fat consumption, particularly food that is high in cholesterol. Encouraging dietary fiber intake (by taking fruits and vegetables) and maintaining optimal body weight may help as well. Does stress affect the cholesterol levels in the body? This is not conclusive though there are researches that suggest so. More recently in 2005, a study found that those who respond to stress largely were three-times more likely to have high LDL level, hence elevating blood cholesterol levels. It is suggested that the adrenal response to stress will increase production of fatty acids which in response increase LDL production in the liver. However the direct relationship of stress with cholesterol levels in the body is still not clear. EL 5 Minutes with Brian Lian Ding Having entered the dietetic practice in 2010, Brian Lian Ding is a professional dietitian and an active member of the Nutrition Support Team at Sarawak General Hospital in Kuching, Sarawak. Here, he talks to us about the dietary sources of good and bad cholesterol amd how one can prevent excess accumulation of bad cholesterol in the body.