Atherosclerosis is often referred to as "hardening of the arteries". This is actually a complex disease which involves tumor-like growths in the wall of arteries. These tumors accumulate high-cholesterol fat and grow to obstruct blood flow through the artery. As the fatty tumors age and grow, they become scarred and often calcified.
Restricted blood flow to any organ reduces its ability to function and obstruction leads to death of tissue. Sudden obstruction of a narrowed blood vessel is often caused by a fatty tumor rupturing and/or a clot forming in a narrowed region of the vessel (thrombosis). If the tissue is vital, such as heart or brain, arterial obstruction may be disabling or lethal.
Serum cholesterol is a predictor of coronary artery disease (but not strokes), and current recommendations set target goals of less than 200 mg % for blood levels. So called "normal levels" range from 180-300 mg%, depending on age and sex. Strict vegetarians may have serum cholesterol levels of less than 100 mg %, considerably less than their lactocarnivorous peer group.
Some of the cholesterol in food is partly digested, or not absorbed, and does not appear in the overall body cholesterol equation. Cholesterol is synthesized in the liver, at the rate of 1000 mg/day. A similar amount of cholesterol per day is secreted in bile by liver cells and circulates through the gastrointestinal tract (GIT). A portion of GIT bile cholesterol is lost through the feces. One way to decrease total body cholesterol is to increase GIT loss. The use of binding resins or fiber to trap bile salts and cholesterol can lower serum cholesterol levels - examples are plant fibers found in fruits, vegetables and grains, psyllium, and the semi-synthetic resin, cholestyramine,
Cholesterol Transporters - LDL & HDL
Cholesterol is incorporated with protein into transport packages, traveling in the blood. These are lipoproteins. Low density lipoprotein (LDL) is "bad cholesterol" since it accumulates in blood vessel walls. Atherosclerosis causes half of all deaths in the U.S. Half of all North Americans have high fat diets associated with elevated blood LDL. High density lipoprotein (HDL), another form of cholesterol traveling in the blood, is "good cholesterol". The ratio of HDL to LDL should be as high as possible.
Circulating LDL is a spherical packet containing 1500 molecules of cholesterol attached to fatty acids and surrounded by an envelope of phospholipid. A single protein, attached to the LDL sphere like a handle, allows it to bind to receptors (LDLR) on the surfaces of cells. The protein handle, apolipoprotein, is essential for LDL clearing, and deficiencies in it lead to a "fat transport disorder".
Circulating LDL is removed when the apolipoprotein binds to LDL receptors (LDLR) on cell surfaces. The receptor moves the LDL packet into the cell which then metabolically processes its contents. Liver cells remove half the circulating LDL. A typical LDL sphere lasts 2-3 days in the blood stream. If LDL clearing is impaired, fat accumulates in the blood, making it thick and viscous like gravy. If a blood sample is allowed to sit for several hours, the cells drop to the bottom of the tube, and the normally clear, straw-colored serum stays on top. The serum with increased LDL looks milky and opaque, with fat droplets.
Some of the LDL in the blood makes its way into the arterial wall where it tends to lodge as an extracellular deposit. Oxidation of LDL by oxygen free radicals seems to damage arterial wall by activating macrophages, immune cells which then organize a damaging inflammatory response. Gradually, a fat-containing inflammatory tumor develops in the arterial wall, growing outward to obstruct the flow of blood. Fat tends to accumulate in the arterial surface where blood flow is turbulent. Arteries branch like trees, and the first turbulent areas to develop fatty plaque are the points of bifurcation of the blood vessels. Once a fatty plaque pushes into the lumen of the artery, more turbulence develops, which promotes more fatty deposition. Antioxidant vitamins can protect against the damaging effects of oxidized LDL. Vitamin C and beta carotene are the most potent antioxidants. Vitamin E is about half as effective. Increased levels of three vitamins will be attractive to nutritional programmers who want to hedge their bets.
Obviously, any deficiency or defects of LDLR will reduce the ability of clearing blood LDL. Paradoxically, dietary fat reduces LDLR activity, so that the more you eat fat, the less you are able to clear LDL from your blood stream. A genetic disorder, familial hypercholesterolemia, arises when the LDLR is defective and blood LDL cannot be cleared; accelerated atherosclerosis leads to heart attacks even in young children! One child with this disorder was given a transplanted liver, which cleared the drastic hypercholesterolemia as the lipoprotein receptors in the new liver began to function.
The Metabolic Solution of Atherosclerosis
Dramatic and expensive operations have rescued many patients from the consequences of bad eating practice and failed to help others. A metabolic solution to the obstructed artery problem is more desirable, cheaper, and safer than attempted surgical rescue.
In our view, proper, adequate diet revision should be aggressively sought as a solution to major endemic disease problems, if not by national policy, then by personal prerogative. The cost of neglecting bad dietary habits may not be affordable in the long-run. Many years ago, in his best-selling book "The Pritikin Promise", Nathan Pritikin advocated a more stringent low fat diet to combat cardiovascular disease. He, like many nutritional theorists, chose one food demon to attack, fat-cholesterol, but he also recommended limiting high protein foods such as poultry, lean meat, and fish to 3.5 ounces per day. Pritikin advocated high vegetable intake but discouraged the ingesting of vegetable oils. But some vegetable oils have important health benefits. Olive oil, for example, is protective against heart attacks.
Ornish treated patients with a very low fat, vegan diet similar to a vegetarian version of the Alpha Nutrition Program and the Pritikin diet. Ornish demonstrated improvement in patients with established coronary artery disease. His patients combined strict diet control with exercise, yoga, and meditation. Fat intake was less than 10%. His conclusion was that corrective diet and life-style changes will reverse established blood vessel disease and improve the quality of life.
The 60 to 100 million Canadians and Americans who have heart disease and the insuring agencies who pay their medical bills should carefully consider the benefits of complete diet revision therapy! To improve the health of modern citizens and to reduce, at the same time, the sky-rocketing costs of health-care, we need to strengthen the concept of self-responsibility for disease-prevention. Each person will have to alter disease-causing habits, change poor eating habits, and stop smoking and drinking, or be accountable for the health problems they choose to retain.
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