ATHEROSCLEROSIS

Atherosclerosis, or "hardening of the arteries", is the build up of fat and calcium deposits inside arterial blood vessels. When the deposits become large, they can partially or completely block the flow of blood. The result is insufficient circulation to the particular organ supplied by that artery. In the heart, insufficient blood circulation may result in permanent damage to the heart muscle, and this condition is known as a heart attack. Permanent damage to the brain due to insufficient blood supply is commonly known as "stroke" or "brain attack".

Atherosclerosis is a fact of life. It occurs in every person, but at different rates and in varying degrees of severity. In some individuals, the atherosclerotic process is slow and gradual, while in others, it may be rapid and advanced leading to stroke and heart attack at an early age.

What factors determine the severity of atherosclerosis and how can we modify these factors? In short, genetics and life style factors. We cannot change our genes, but we can modify our life styles to slow  atherosclerotic process. One of the most important factors that can be readily (though not necessarily easily) modified is cessation of smoking. Smoking not only causes cancer and emphysema, but also accelerates atherosclerotic build up in arteries. High blood pressure that is not adequately treated, resulting in constant high pressure and subsequent damage to the arterial walls, also leads to premature atherosclerosis. Similarly, poorly controlled diabetes accelerates the process. Therefore it is important to seek and comply with medical treatment of these conditions.

Another important factor we can control is the blood cholesterol level. Maintaining a level less than 200 mg % is generally considered favorable. However, it is also important to have higher levels of "good cholesterol" (HDL), and lower levels of "bad cholesterol" (LDL). Decreasing dietary intake of saturated fats, trans monounsaturated fats and cholesterol lowers the blood cholesterol level. These dietary fats raise the blood cholesterol level by increasing the amount of LDL, or bad cholesterol. (1) Animal and dairy products are the primary sources of saturated fat and the only source of cholesterol in our diet. (Cholesterol is not found in plants.) Trans monounsaturated fats are derived primarily from hydrogenation of vegetable oils. On the other hand, increase in polyunsaturated fats (from vegetable and fish oils), especially omega 6 and 3 essential fatty acids correlates with a decrease in total cholesterol. A diet high in Omega 3 fatty acids, primarily derived from fish oils, is also associated with a lower risk of heart disease.

Dietary fiber also plays an important role in the reduction of cholesterol level. Increasing soluble fiber (guar gum, psyllium, pectin) intake correlates with lower cholesterol levels primarily due to a decrease in LDL cholesterol. Dietary fiber offers additional health advantages with respect to a variety of gastrointestinal disorders and control of blood sugar in diabetics.

Exercise also plays an important role in lowering cholesterol and decreasing the risk of heart disease. Regular aerobic exercise, preferably 20 min per day, at least three days per week, also lowers cholesterol by decreasing LDL and increasing HDL. Even if these exercise goals are not met, any increase in daily physical activity is healthful.   Daily physical acitivity may be increased by simple measures such as taking the stairs instead of the elevator.

In summary, there are many factors we can modify to  slow the atherosclerotic process: cessation of smoking; complying with  treatment of high blood pressure and diabetes; exercising regularly; and modifying our eating habits. We will lead healthier lives by decreasing fats from animal products and replacing these calories with foods containing fiber and polyunsaturated fats.

1. Grundy SM. Nutrition and Diet in the Management of Hyperlipidemia and Atherosclerosis. In: 2. Shills ME, et. al., eds. Modern Nutrition in Health and Disease, 9^th ed. Baltimore: Williams      and Wilkens, 1999, 1199-1216