Discuss the link between CHD and a high fat diet.

Fat content in our diet is highly associated with the Coronary Heart Disease, but we have to consider the types of fat when determining the risk of getting CHD. A diet consisting high saturated fats and trans fats leads to high levels of cholesterol, which in effect results in a greater risk of coronary heart disease and heart attack. On the other hand, polyunsaturated and monounsaturated fats would lower the risk of heart diseases.

Cholesterol, a fat crucial to many metabolic functions, is produced in the body from the food we intake and is produced in the liver. There are two major kinds of blood lipids that contain cholesterol: Low-density lipoproteins (LDL), called “bad” cholesterol as it carries cholesterol to tissues from the liver and high-density lipoproteins (HDL), called “good” cholesterol as it helps remove cholesterol from arteries. The risk of getting CHD increases with a diet of a high level of LDL and a low level of HDL.

Saturated fats found in animal products as well as processed foods and trans fats in oil increase LDL cholesterol in the blood. This leads to the buildup of fat and cholesterol in the blood and the first signs are shown as fatty streaks. They can develop into atherosclerotic plaque, which is composed of lipids, cholesterols, cell debris, and calcium. The endothelium of each artery starts smooth, but as the plaque builds up inside the lining of an artery, it is damaged. As the plaque deposits and the endothelium gets roughening, the lumen of the artery gets narrower. This process of atherosclerosis would reduce the oxygen-rich blood flow through the coronary artery to the heart. It is chronic if the coronary artery is narrowed over time and this would give angina, chest pain. It is acute when there is a sudden rupture of a plaque resulting in a formation of a clot, or thrombosis. This would result in a heart attack, as the atheroma cuts off the supply of oxygen-rich blood to heart muscle.

On the contrary, there are fats that protect against heart disease. These include oily fish and some vegetables oil. Oily fish such as sardines, tuna, mackerel and salmon which contain omega-3 fatty acids is said to decrease triglycerides and increase HDL-cholesterol levels. Blood becomes less likely to clot or be blocked as this fat improves blood vessel elasticity and thins the blood. Some vegetable oils containing omega-6 fatty acids include corn, soy and safflower and those such as canola and olive oil contain omega-3 fatty acids. These help in lowering LDL cholesterol and increasing HDL and can be used instead of saturated fats such as butter.