Saturday, April 25, 2015

The Cholesterol Controversy

By Mark Johnson


With all the negative publicity cholesterol has been receiving lately, you might think that cholesterol is "Public Health Enemy No. 1." A growing number of medical authorities claim that high dietary and blood cholesterol is the primary cause of the epidemic heart disease that kills almost half the adults in the United States. Concern about cholesterol has caused millions of Americans to embark upon radical diet and lifestyle changes to lower its level in their blood. Is it really necessary to avoid all cholesterol-rich foods, such as eggs, meat, cheese and shellfish, if you wish to avoid heart disease? 
The answer is a qualified no. 
 However, it is better to limit most of these items to the category of occasional use.

What Cholesterol Is and Where It Comes From


Far from being some noxious, alien invader of our bodies, cholesterol is a solid, waxy substance produced by all animals as part of their normal metabolism. Cholesterol is not a fat itself, but it is always found with fats in animal derived foods. Cholesterol is technically classed as a lipid, a group of fat and fat-like substances that are all insoluble in water but soluble in fat solvents. Other lipids include fats, fatty acids, oils, waxes, strolls and esters of fatty acids. Because cholesterol is absolutely essential to animal life, your liver routinely makes 800-1500 mg per day of cholesterol from dietary saturated fats and simple sugars. And indeed, strict vegetarians are fortunate their livers can make cholesterol, since no foods of purely vegetarian origin contain cholesterol. And if their blood and tissue levels of cholesterol were to drop to zero, death would rapidly ensue!

Most people can absorb no more than 300-500 mg pr day of cholesterol directly from foods. Radioactive tracer studies, which use special radioactive food molecules to trace their fate in the body, have shown that 60-70% of all blood cholesterol comes from production by the liver, not from pre-formed cholesterol in the foods. In fact, a recent article in the American Journal of Clinical Nutrition by D.M.Hegsted reviewed the scientific evidence concerning the connection between dietary cholesterol and blood cholesterol levels. Hegsted noted that in the usual range dietary cholesterol intake,(0-400mg/1000 calories of food), each additional 1 mg/1000 cal. of dietary intake results in only a 1/10 mg increase in blood cholesterol levels. And indeed, epi-demiological studies from around the world have uncovered many cultures living on extremely high fat and cholesterol diets whose blood cholesterol levels are low. The Masai tribe in Southern Africa,for example,have been heavily studied by heart and cholesterol researchers. These people have been cattle herders for thousands of years, and live almost exclusively on a cholesterol and fat-rich diet of meat, milk and blood. Yet their blood cholesterol levels typically run a pristine 150, a level most cholesterol conscious American doctors would consider perfect!

Why Your Body Makes Cholesterol


Cholesterol is important to every cell of your body. It provides needed rigidity to all cell membranes. Every cell in your body is covered by a membrane made largely of cholesterol, fat and protein. Membranes are porous structures, not solid walls, letting nutrients and hormones in, while keeping wastes and toxins out. Without adequate cholesterol, cell membranes become too fluid, and not rigid enough. If your cell membranes suddenly became totally devoid of cholesterol, your cells would explode from their internal water pressure like over-filled water balloons. Brain cells are particularly rich in cholesterol, the brain being about 7% cholesterol by dry weight.

One of cholesterol's most important functions is to serve as the basic raw material from which your body makes many major steroid hormones, including testosterone, estrogen, progesterone, cortisone and aldosterone. Without these first three hormones you would have no sex life; without cortisone your body could not cope with stress; and without aldosterone your body could not properly balance your sodium and water levels.

Large amounts of cholesterol are found in the skin, where it makes the skin highly resistant to the absorption of water-soluble toxins.The skin's cholesterol also helps hold water in the body, so that loss of water through skin evaporation is only about half to one pint daily, instead of the four to ten quarts of water which would be lost if not for skin cholesterol.

Even your solid bones would be hollow and brittle, if not for cholesterol. Vitamin D, the chief nutrient and hormone regulator of body calcium an phosphorus metabolism, is also made from skin cholesterol. Natural sunlight hitting cholesterol in your skincell membranes turns the cholesterol into Vitamin D. And after further metabolic processing by liver and kidneys, vitamin D is the chief controller of how well your body absorbs dietary calcium and phosphorus.

A major portion (as high as 70%) of the body's cholesterol is used by the liver to produce bile salts. Bile salts are used during food digestion to emulsify fats and the fat-soluble vitamins A,D,E and K for proper absorption. Without these cholesterol-rich bile salts,your body could not absorb essential fatty-acids or the fat-soluble vitamins, and serious, even lethal, deficiency diseases would ensue. The liver, which is the body's poison control and detox organ, also dissolves some fat-soluble toxins in the bile salts. After these toxin-laden bile salts have been dumped into the intestine, they may then be excreted from the body in the feces.

Why Are People Concerned About Cholesterol?


Your liver makes not only cholesterol, but also two main carrier molecules, LDL and HDL, which bind with cholesterol. Without help of these carrier molecules, cholesterol could not travel through the blood stream. LDL (Low Density Lipoprotein) carries cholesterol out to all the tissues in the body, where it may be used for various metabolic functions, including production and repair of cell membranes, as well as hormone production. Unfortunately LDL-bound cholesterol also tends to stick to damaged artery linings, where it may accumulate, eventually plugging up the arteries and blocking blood flow. This is why LDL cholesterol often is referred to as the "bad" cholesterol.

However, it is important to note that LDL cholesterol tends to stick primarily to damaged artery linings. Some of the many factors which have been shown to contribute to this artery-lining damage include the following: 1) Inadequate vitamin C intake- C is critical for the production of collagen and other substances which ensure the integrity of artery linings; 2) Inadequate vitamin E intake- E suppresses excessive formation of an artery-lining damaging substance called thromboxane A2 (TXA2); 3) Inadequate vitamin B6 intake, B6 suppresses formation of artery-damaging homocysteine, an abnormal methionine metabolic produced when people consume high protein/low Be diets; 4) Inadequate cellular production or dietary intake of gamma linolenic acid (G.A.). G.A. is an important fatty acid essential to make prostaglandin A. (PGE1), which turn inhibits production of artery-damaging TXA2 while promoting production of prostacyclin (PG12), a prostaglandin which promotes healthy, smooth artery linings; 5) Excessive intake of various pollutants, including cigarette smoke; alcohol; sugar; hydrogenated, heat damaged fats; overcooked protein; and auto/diesel exhaust. It is important to note that the same prostagladins which play such a vital role in artery protection also are responsible for pain perception. Consequently, as you take more pain killers such as aspirin and ibuprofen, you contribute to the damaging process.

Thus, although it may be prudent to lower your blood levels of LDL cholesterol, it is equally important to ensure adequate intake of the various artery -lining protecting nutrients (E,C, etc.) While avoiding as much as possible the various toxins which damage artery linings (tobacco smoke, alcohol, rancid fats etc.). A major review article by Earl Benditt in Scientific American concerning heart disease and artery lining damage makes it clear that the LDL cholesterol sticking to artery linings is a late stage of the atherosclerotic process. The multiple-cause damage to artery linings by smoking, alcohol, rancid fats and nutrient deficiency is a prior, earlier and at least partially preventable/reversible stage of the lifelong development of heart/artery disease. HDL (High Density Lipoprotein) carries cholesterol back to the liver from tissues throughout the body, if the diet is high in fiber. The excretion of cholesterol in the form of fiber bound, used bile-salts is the major way the body rids itself of excess cholesterol. Since HDL makes this process possible, HDL cholesterol is often called the "good" cholesterol.

Dr. Sheldon Reiser of the USDA has published research in the 1980's demonstrating that dietary sugar plays a major role in blood cholesterol levels. Reiser has found that a high dietary sugar intake raises blood triglyseride (blood fat) and LDL ("bad") levels, while lowering HDL ("good") levels. Reiser's work indicates that it is the fructose (fruit sugars) component of ordinary white sugar which so powerfully elevates blood cholesterol (white sugars, called sucrose, is a combination of one glucose and one fructose molecule). Considering the popularity of fructose as a "natural" sweetener in many carbo-lading, energy, diet and soft drinks and powders lately, Dr.Reiser's work takes on an added significance. The benefits claimed for fructose-sweetened foods and beverages--that they have a low "glycemic index" and thus disturb blood sugar levels less than white sugar--may be more than offset by fructose's blood cholesterol raising power. Dr. Reiser's work makes it clear that the worst combination for creating elevated blood cholesterol, even on a low cholesterol diet, is foods rich in both fat and sugar. Considering America's mania for sugar and fat rich desserts and snacks, America's high national average blood cholesterol levels may be due as much to this dietary imbalance, as to our high national intake of meat and dairy foods. It is relevant to note here that America's per capita consumption of meat, eggs, butter and cream has dropped significantly from 1900 to the present, while America's per capita sugar consumption has risen from a very modest 5 pounds per year in 1800 to about 190 pounds per year in the 1990's!

Ratios Are More Important


Because high HDL levels are actually considered health protective, while high LDL levels are considered indicators of health risk, it is important to look at their relative proportions in your blood when evaluating your personal cholesterol profile. HDL and LDL are the main components of total; blood cholesterol. The average American ratio of total cholesterol to HDL is 5 to 1. A total to HDL ratio of 5 represents therefore an average heart health risk, while a lower ratio of 3.4 represents half the American heart attack health risk. If the ratio of total to HDL rises to 9, this represents twice the average heart health risk. For example, if your total cholesterol level is 189 mg/dl of blood, while your HDL level is 63 mg/dl, then your total HDL ratio =189/63=3. If your total cholesterol level were a seemingly healthy 180 while your "good" level was a low 20, then your ratio 180/20=9, would twice the average risk of heart attack. So it is important to know your HDL as well as total blood cholesterol, if you want a more accurate indicator of your risk.

Current research suggest that blood cholesterol levels should ideally measure under 200 and certainly under 250. However, even a total cholesterol of 250-280 may not be serious cause for alarm, if your HDL levels are high, and if you protect your heart health in other ways such as not smoking, minimal or no alcohol consumption, regular exercise, etc. It is also important to remember that the connection between blood cholesterol levels and heart disease is a statistical phenomenon, only truly accurate when applied to estimating heart health risks of large groups of suffer a heart attack, while 15% of all fatal heart attacks will occur in people whose cholesterol were under the current "magic" number of 200. Roslyn Aflin-Slater, a noted academic nutritionist, has pointed out that science has identified 35 different risk factors for heart disease, including genetic predisposition, smoking, diabetes, high blood pressure, and low exercise levels, with high blood cholesterol being only one of these 35 factors.

Recent research suggests the following lifestyle measures can be helpful in lowering total and LDL cholesterol, while raising HDL cholesterol.
  • Regular aerobic exercise: jogging, brisk walking, bicycling, etc.
  • Practicing stress reduction techniques: meditation, prayer, laughter, etc.
  • Reducing dietary saturated fats and simple sugars from the average American levels of 40-45% fat calories and corn syrup, honey, etc., are the two foodstuffs your liver is an expert at turning into blood cholesterol.
  • No smoking and minimal alcohol intake.
  • A high fiber diet: whole grains, beans, peas, lentils and fresh vegetables.
  • Using olive oil as the primary salad and cooking oil, or flaxseed oil. These oils are high in monosaturated fats which contribute to the elevation of HDL and the apparent reduction of LDL cholesterol.
  • Maintaining proper weight. This is best done by exercise and low-fat foods which are high in nutrient quality.
  • Frequent consumption of fish that are rich in the fatty acids EPA and DHA, such as sardines, salmon or cod, or of EPA/DHA rich fish oil capsules.
  • Avoid animal foods fried in oil. Research indicates this always produces cholesterol oxides in the food, and that these cholesterol oxides may be the real culprit insofar as food derived cholesterol does damage artery linings.
  • Seriously reduce intake of hydrogenated vegetable oils, shortenings and margarines. The trans-fatty acids produced by the hydrogenation process have been shown to exert a major anti-essential fatty acid effect. Trans-fatty acids also seriously impair the liver's conversion of HDL cholesterol to bile salts for intestinal excretion. Most hydrogenated vegetable oils, shortenings and margerines tested by M. Enig, a professional oil chemist, routinely contain 15-40% trans-fatty acids.

How Cholesterol Can Be Controlled


The level of cholesterol in our blood and body tissues is controlled by the interaction of four variables. These are:
  1. The amount of cholesterol absorbed from foods.
  2. The amount of cholesterol synthesized by the liver from dietary saturated fats and simple sugars
  3. The rate at which cholesterol is converted into bile salts and transferred to the intestine for fecal excretion.
  4. The rate at which cholesterol rich bile salts are reabsorbed along with the dietary fats they emulsify, and converted back into cholesterol in the liver.
  5. Reducing total blood cholesterol levels; all fibers in 1) and 4), GFT chromium, copper, calcium, vitamins C and E.
  6. Raising "good" HDL cholesterol levels: GFT chromium, copper, niacin (B3), vitamins C + E.
  7. Lowering "bad" LDL cholesterol levels; oat bran, guar gum, copper, niacin (B3), vitamin C.

Bibliography


  1. Turley, S.D. and Dietschy, J.M. "The Metabolism and Excretion of Cholesterol by the Liver," in The Liver: Biology and Pathology, pp. 617-642, ed. By I.M. Arias Raven Press, N.Y. 1988.
  2. Reiser, S. "Physiological Differences between Starches and Sugars," in Medical Applications of Clinical Nutrition pp. 133-177, ed. By J. Bland, Keats Pub. New Canaan, CN, 1983.
  3. Kummerow, F.A., "Nutrition Imbalance and Angiotoxins as Dietary Risk Factors in Coronary Heart Disease." Am. J. Clin Nutr. 32:58-83, 1979.
  4. Martin, W. "The Combined Role of Atheroma, Cholesterol Platlets, the Enodthelium and Fibrin in Heart Attacks and Strokes." Med Hypotheses 15:305-322, 1984.
  5. Enig, M.G. et al. "Fatty Acid Composition of Fat in Selected Food Items with Emphasis on Trans Components." J of Am. Oil Chem. Soc. 60:1788-1795, 1983.
  6. Mann, G.V. "Diet-Heart: End of an Era." New England Journal of Medicine 297:644-650, 1977.
  7. Bendit, E. " The Origin of Artheriosclerosos." Science American 236/274-85, Feb.1977.
  8. Turley, S et al. "Role of Ascorbic Acid in the Regulation of Cholesterol Metabolism and the Pathogenesis of Atherosclerosis." Atherosclerosis 24:1-18, 1989.
  9. Railes, R. And Albrink, M.J. "Effect of Chromium Chloride Supplementation on Glucose Tolerance and Serum Lipids including High Density Lipoprotein of Adult Men." Am.J. Clin. Nutr. 34:697-700, 1992.
  10. Mattson, F.H. et al. "Optimizing the Effect of Plant Sterols on Cholesterol Absorption in Man." Am. J. Of Clin. Nutr. 35:697-700, 1992.
  11. Malinow, M.R. et al. "Alfalfa." Am. J. Clin. Nutr. 1810-12, 1979.
  12. Grundy, S.M. et al. " Influence of Nicotinic Acid on Metabolism of Cholesterol and Ytriglycerides in Man." J.Lipid Res. 22:24-36, 1981.
  13. Hermann, W.J. et al "The Effect of Tocopherol on High Density Lipoprotein Cholesterol: A Clinical Observation." Am.J. Clin.Path. 72:848-852, 1979.
  14. Truswell, A.S. "Effect of Citrus Pectin on Blood Lipids and Fecal Steroid Secretion." Am.J. Clin. Nutr. 30:171-175, 1977.
  15. Kirby, R.W. et al. "Oat- Bran Intake Selectively Lowers Serum Low-Density Lipoprotein Cholesterol Concentrations of Hypercholestremic Men." Am J. Clin. Nutr. 34:824-829,1981.
  16. Werbach, M.R. "Atherosclerosis," in Nutritional Influences on Illness: A Sourcebook of Clinical Research, pp 40-77, M.R. Werbach, M.D.,Ph.D.(School of Med.,UCLA) Third Line Press, Tarzana, CA, 1988.
  17. Alfin-Slater, R. And Howton, D. Lipids, D. Lipids: Chemistry, Biochemistry and Nutrition. Plemum Publ.,N.Y.1993.

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