High fat diet leads to coronary Heart disease. Discuss

High fat diet leads to Coronary Heart Disease. Discuss

Cholesterols are components that already exist in the blood made by the body itself. It is essential for formation of plasma membranes and myelin, the substance that surround nerve fibres and is necessary for formation of hormones and vitamin D.

There are two types of cholesterol in body: one that benefits human health is HDL (high density lipoprotein) as it mops up cholesterol and takes it to liver to be broken down. Another is LDL (low density lipoprotein). Most of cholesterol in our body is in form of LDL. Body regulate the concentration of LDL. The plasma membrane of cells have LDL receptors in body which recognizes a LDL particles. Higher concentration of LDL induces formation for more of the receptors by increase the number of binding sites. LDL particles bind to receptors and are pulled into the cytoplasm, thus the LDL concentration is reduced.

However, if LDL (low density lipoprotein) concentration is in excess, the body is unable to control and break down the cholesterols. Thus the LDL is rapidly transported across an intact endothelium and become trapped in three dimensional cage work of fibers secreted by the artery wall cells. The intimate association of LDL with the extracellular matrix cells explain the usual phenomenon of higher concentration of LDL found in artery wall than plasma. This leads to early lesions to develop in sites of predilection. The cells of artery wall then, secretes oxidative products from multiple pathways that seed the LDL trapping in subendothelial space and initiate lipid oxidations. When LDL is further oxidised, the protein proportion of LDL is also modified leading to loss of recognition by the LDL receptor and a shift to receptors that recognise oxidised LDL receptors. This shift lead to massive accumulation of cholesterol. Therefore it results in massive accumulation of cholesterol. This can lead to narrowing and blockage of coronary arteries, in other words 'atherosclerosis'

Atherosclerosis can occur which is hardening and narrowing of the arteries due to deposition of cholesterol. Atheromas (fatty deposits) can develop in arteries and reduce the diameter of the lumen (stenosis). The restriction in blood flow increases pressure in the artery leading to increase in shear stress via forceful pressure exerted on the artery wall. The damaged region is repaired with fibrous tissue but this reduces the flexibility of the vessel wall. Also the deposition of cholesterol can lead to plaque formation. Plaque contains high fatty substances such as cholesterol, platelets, fibrin, calcium ions and cellular debris. They easily attach to the roughened part of the artery lining. Plaque rupture exposes the flowing blood to tissue factor in the lesion, and this induces thrombosis. Continuous intake of high fat diet, can over time, lead to increase in amount of plaque in blood and lumen of arteries can continually reduce to extreme. Plaque can rupture over time, which can trigger processes of thrombosis. Clotting factors can aggregate form thrombus which restricts the blood flow. If thrombus dislodge, it becomes embolus and can cause blockage in small arterioles.

Atherosclerosis can lead to cardiovascular disease after arterioles are occluded and cease to function. If coronary artery is completely blocked, it can cause an acute myocardial infarction (heart disease). There is strong correlation between LDL and CHD.

A high fat diet leads to CHD. Discuss

My conception towards the relationship between a high fat diet and CHD has been quite simple and linear: saturated fat builds up LDL cholesterol in blood, which leads to accumulation of plaque in arteries, ultimately causing CHD. This notion has been taken for granted for decades, regarded as an irrefutable truth, motivating numerous people to practice so-called healthy vegetarian diet. However, a recent study published in numerous prominent scientific journals has opened a new horizon that may debunk the deeply-ingrained idea of high saturated fat diet and CHD.

The result from the study conducted by American Society for Nutrition suggests that: i) high cholesterol/saturated fat is not the primary cause of CHD and ii) consuming vegetable oils, widely known to be ‘heart-healthy’, leads to heart diseases. According to British Medical Journal, trans-unsaturated fats that were considered to be benign to humans actually increase the risk of CHD. Eating margarine, processed cakes and microwave popcorn regularly may increase the risk of death from CHD by 28%. Vegetable oils, which is often groundlessly titled as one of the ‘healthy oils’, contain polyunsaturated fats that also increase the chance of getting CHD. Omega-6 and omega-3, when consumed in excess amount, may cause structural damage to our fat stores and cell membranes.

Replacing saturated fats with carbohydrates has even more significant health impacts: increased risk of CHD and mortality, increased inflammation, impaired glucose tolerance and increased small, high-density LDL particles.

Although these findings are groundbreaking, the only drawback of the studies is that most of these studies are meta-analyses (statistical analysis that combines the results of multiple previously scientific studies), thus showing the association but not causation. Since the findings emerged only recently, researchers are currently going through the process of collecting empirical data (it would be a long-term data because it is dealing with ‘death’ and ‘coronary heart diseases’).

http://www.nutrition-coalition.org/saturated-fats-do-they-cause-heart-disease/

http://articles.mercola.com/sites/articles/archive/2015/08/31/saturated-fats-heart-disease.aspx

https://chriskresser.com/new-study-puts-final-nail-in-the-saturated-fat-causes-heart-disease-coffin/

https://www.newscientist.com/article/dn28034-trans-fats-not-saturated-fat-linked-to-heart-disease-risk/

https://www.hsph.harvard.edu/nutritionsource/2014/03/19/dietary-fat-and-heart-disease-study-is-seriously-misleading/

A High Fat Diet leads to CHD. Discuss

Although the impact might not be direct, a high fat diet provides factors that lead to CHD.

 Coronary Heart Disease has several risk factors associated, and one of the main factors is high level of cholesterol.  Cholesterol is a fat made by the liver from the saturated fat in diet. Cholesterol is essential for healthy cells, but too much in the blood can lead to CHD. Cholesterol is carried in the bloodstream by molecules called lipoproteins. Low density lipoproteins (LDL) is often referred as ‘bad cholesterol’. This is because it carries cholesterol to tissues including heart arteries, whilst High-density Lipoprotein (HDL) helps remove cholesterol from arteries to livers, where it is broken down. LDL cholesterol is harmful as it tends to build up on the walls of the coronary arteries. LDL cholesterol makes up fatty deposits called atheroma and this builds up on the walls of the coronary arteries. This makes the arteries narrower, restricting the flow of blood to the heart muscle. This process is called atherosclerosis.

Moreover, A high fat diet influences the chance of getting CHD by developing diabetes. High-fat diet and obesity cause beta cells to lose their ability to sense glucose in the blood, which is diabetes type 2. Diabetes lead to CHD as it cause the lining of blood vessels to become thicker, which can restrict blood flow. This leads to atherosclerosis, doubling the risk of developing CHD.

However, there are some factors that are not necessarily related to high-fat diet. Smoking is a major risk factor for CHD as both nicotine and carbon monoxide put a strain on the heart by making it beat faster. Moreover, some factors associated with the likelihood of developing CHD are related to a person’s environment and lifestyle. Lack of exercise contributes to obesity and high blood pressure, which causes strain on heart and make it pump harder. Sometimes, factors are even uncontrollable. These includes person’s gender, as men are more likely to have CHD than women, and person’s age as CHD is more prevalent in older people. Also there are genetic factors, as CHD tends to occur more frequently in some families than others with similar lifestyle.

In conclusion, it is not only single factor that contributes to CHD, but complicated interactions of many factors. For instance, although one may have inherited the genes for CHD, it may not be expressed if he or she has a healthy lifestyle. Vice versa, one can develop CHD without any social or genetic factors if diet are not balanced. However, I personally believe high-fat diet is the most hazardous factor, as it leads to several different conditions such as atherosclerosis, diabetes and obesity, which increase the likelihood of developing CHD.

Reference :

- https://www.nhlbi.nih.gov/health/health-topics/topics/hd/atrisk

- http://www.world-heart-federation.org/cardiovascular-health/cardiovascular-disease-risk-factors/diet/

- Oxford IB Biology Textbok

 

 

A High Fat Diet leads to C.H.D: Discuss

Mark Koo Yr13

  Coronary Heart disease is a disease, in which waxy substance called plaque builds up inside the coronary arteries. Coronary arteries play an important role, supplying oxygen rich blood to our heart muscle. When plaque builds up in the arteries, the condition is called atherosclerosis. Over a long period of time, the plaque hardens and ruptures. The hardened plaque tends to block the blood flows in the arteries; also there will be a blood clot if the plaque ruptures. This acts as a blockage of coronary arteries. 

  High levels of cholesterol in the blood may be caused by having a genetic susceptibility, however, it is mainly caused by consuming too much saturated fat containing foods.

  Cholesterol is a fat made by the liver from the saturated fat in our diet. Cholesterol is essential for hormone production such as sex hormones, bile and vitamin-D production, and cell membrane support, however too much consumption leads to C.H.D. Cholesterol is carried in the bloodstream by the molecule called lipoprotein. There are two main types of lipoprotein: Low Density Lipoprotein (LDL) & High Density Lipoprotein (HDL). LDL is the one that causes the C.H.D, which tends to be stuck on the surface of the wall of coronary arteries, and it is from the saturated fat diets.

  

  The low density lipoprotein is affected by our diets (unsaturated fat). Our body, liver, naturally produces cholesterol, which includes LDL, so that the additional LDL from our high fat diets increases risk getting C.H.D even further.

  However, not only high fat diet that causes C.H.D, there are other factors that cause the disease. Individuality varies with people; some people who do not consume high fat diet also might have C.H.D due to genetic factors. Furthermore, Abetalipoproteinemia (ABL) and familial hypobetalipoproteinemia (FHBL) are relatively uncommon inherited disorders of lipoprotein metabolism that cause low cholesterol levels, but the person who has the disorder exhibit an enhanced tendency to develop C.H.D.

  Smoking, lack of exercise, high blood pressure, and obesity also can lead to C.H.D. These factors and high fat diet are acquired factors; and the genetic problems can seen as a innate factors that cause C.H.D.

WebMD. (2016). A Look at Coronary Artery Disease. [online] Available at: http://www.webmd.com/heart-disease/guide/heart-disease-coronary-artery-disease [Accessed 18 Aug. 2016].

High-fat diet leads to Coronary Heart Disease. Discuss.

 

           A high-fat diet, and coronary heart disease. It seems like the liver takes no part in these two events. However, coronary heart disease is actually closely related to the function of the liver.

           Liver, the largest organ in the human body which consists 3-5% of the body weight, is one of the most vital organs that carries out numerous pivotal functions. To name a few, Kupffer cells in sinusoid of the liver break down erythrocytes (which has a lifespan of approximately 120 days), detoxify toxic substances in our body (alcohol detoxified by enzyme alcohol dehydrogenase), store excess glucose in our body in the form of glycogen using insulin produced by beta-islets of Langerhans, and produce plasma proteins. The function of the liver that is highly linked to coronary heart disease, however, is regulation of lipids.

           These lipids include cholesterol or lipoproteins. The recent research classifies High-Density Lipoprotein (HDL) as a ‘good’ cholesterol and Low-Density Lipoprotein (LDL) as a ‘bad’ cholesterol. The difference between them is the proportion of lipid to protein. HDL contains a higher proportion of ‘healthy’ protein than LDL does. Whenever lipid level gets too high in our body, hepatocytes synthesise those into cholesterol for internal usage. This process includes synthesis of vitamin D, steroid hormones, bile production, and cell membrane construction.

           When a person intakes an excess amount of lipids (high saturated fat diet), then all of the cholesterol processing mechanisms produce much more cholesterol than our body requires. Since there is a point when no more vitamin D, steroid hormones, bile salts, or new cell membrane construction is necessary, no more cholesterol, produced by hepatocytes, can be utilised for essential purposes, hence leaving the excess amount of ‘bad’ low-density lipoproteins in the bloodstream. This cholesterol eventually accumulates underneath the endothelium layer of the blood vessels, which leads to the swollen inner wall and narrower lumen. This phenomenon is called atherosclerosis.

           When the lumen gets narrower, the blood pressure drastically increases as well and therefore leads to rupture of endothelium. Naturally, by the sequence of cascade reaction of some of the plasma proteins (platelets -> prothrombin to thrombin -> fibrinogen to fibrin), blood clot forms on the inner wall of the blood vessel. This process is called coronary thrombosis.

           When these blood clots detach from the endothelium and swim around the bloodstream, the situation gets serious. When solid blood clots move around the circulatory system and end up stuck in an extremely narrow coronary artery (a crucial artery used to supply oxygen for myogenic contraction of the heart muscle), oxygen supply for the heart is halted, leading to the ceasing of the heart’s ‘blood-pumping’ activity. This can ultimately cause an array of coronary heart diseases (CHD) and can be expressed by treacherous symptoms such as myocardial infarction.

           To conclude, for the following reasons and phenomena stated above, the idea that high-fat diet leads to coronary heart disease is categorically true.

 

A high fat diet leads to coronary heart disease (CHD). Discuss.

Usually, the lipid that is associated the most with coronary heart disease is cholesterol. Because of this cholesterol has received a bad reputation over the years as one of the main agent causing CHD.

Like all essential nutrients, cholesterol is necessary in small amounts. However, most modern diet incorporates too much saturated and trans fat which raises the level of low-density lipoprotein (LDL) cholesterol. Too much LDL cholesterol is bad because it contributes to the buildup of plaque which if not treated can cause CHD.

Patients who suffer from high LDL cholesterol concentration in blood are advised to replace their saturated fat intake (animal fat) with unsaturated fat intake (vegetable oil). They are also advised to consume food rich in fiber (vegetables) and complex carbohydrates (whole grains). This is because unsaturated fats, fiber and complex carbohydrates help raise the level of high-density lipoprotein (HDL) cholesterol. HDL cholesterol is good because it helps remove LDL cholesterol from arteries and bring it to the liver where it is broken down and excreted.

Although a high-fiber and a high-carbohydrate diet increases the level of HDL cholesterol and therefore decreases the level of LDL cholesterol, it is not always a good choice for someone with a high triglyceride concentration in their blood to follow this diet. Triglycerides are often an overlooked lipid compared to LDL cholesterol when it comes to CHD. However, overconsumption of triglycerides is also a major cause of CHD. Since a diet rich in carbohydrates (and of course fats) can raise the level of triglyceride in one’s body, patients with high triglyceride concentration are advised to implement a low-carbohydrate diet.

In conclusion, a diet high in saturated and trans fat increases the risk of CHD, while a diet high in unsaturated fat has a potential to decrease the risk of CHD. Also, a high-carbohydrate diet can increase the risk of CHD. However, CHD is not influenced by diet alone as there are many other factors such as genetics.

A high fat diet leads to CHD. Discuss.

Yvette Kim

CHD is short for Coronary Heart Disease, which is the stiffening and deposition of atheroma in the coronary arteries at the heart. A complete blockage, thrombosis, in the coronary arties will lead to a heart attack. The amount of different types of fats in a person’s diet is correlated with the risk of CHD.

In western regions of the world, it is common to observe the positive correlation of saturated fatty acids and CHD incidence. Saturated fatty acid deposits in the arteries may combine with cholesterol to lead to atherosclerosis, which is a condition that leads to high blood pressure by a decrease in lumen diameter. Saturated fatty acids are most commonly found in animal products and processed foods.

Meanwhile, unsaturated fatty acids (monounsaturated and polyunsaturated) found in vegetable oil show a weaker relationship with the incidence of CHD. The unsaturated fatty acids do not deposit in the arteries nor combine with cholesterol.

However, a diet high in trans fatty acids, made through hydrogenation of liquid plant oil or naturally present in meat, increases the consumption of cholesterol, increasing the risk of CHD. Yet, trans fatty acids are not commonly over consumed as much as saturated fatty acids.

Cholesterol, a fat produced by the liver from consumed fats, are, as mentioned frequently, hold a relationship between high fat diets and CHD incidents. LDL cholesterol is referred as ‘bad’ as it forms atheroma. HDL cholesterol is referred as ‘good’ as it helps remove cholesterol away and back to the liver to be broken down. LDL and HDL are produced both by saturated fatty acids. Hence, saturated fatty acids must be considered as harmful only according to the amount of consumption, not just its type.

Considering that all fatty acids are high in energy content, a risk of obesity is always correlated to fatty acid consumption regardless of their type. As obesity puts further strains on the heart, it may be suitable to conclude that a high fat diet does cause CHD.

Fat consumption is not the only cause of CHD. Age, gender, genetic factors, lack of exercising and smoking are all different causes of CHD. Blood vessels stiffen with age while lack of exercising leads to obesity and nicotine in cigarettes promotes vasoconstriction, increasing blood pressure. Other chemicals in cigarette smoke harm the tissue of arteries, causing other heart diseases as well. A family history of CHD is also a cause as lifestyles of smoking, lack of exercise and diet can be similar within family members. 

Bibliography:

Biology for the IB Diploma (second edition)