Regarding minerals, the calcium-magnesium interchange and the sodium-potassium relationship affect hardening of the arteries and blood pressure. Even copper and zinc deficiencies and imbalance may be related. It is clear however, that the saturated fats and cholesterol in the diet are linked to CVD in all animals studied, including the human species. Carnivorous animals, such as dogs and cats, seem relatively immune to high-fat diets. Possibly understanding their protection will give us further insight into CVD prevention.

The relationship of cholesterol has been and continues to be the biggest controversy in this area. Current thinking is that high blood cholesterol, especially with higher LDL cholesterol (the "bad" kind) and lower HDL cholesterol (the "good" kind, because it picks up used cholesterol and carries it back to the liver), is a significant factor correlated with atherosclerosis, coronary artery disease, and early death. The very large Framingham study showed that people with a blood cholesterol level of 260 mg. had three times the incidence of myocardial infarctions that those with levels of 195. Lowering cholesterol levels by whatever means?diet, weight loss, exercise, and even drugs?decreased the risk of heart attacks. Yet there may be other variables; this cholesterol picture may just be the surface factor.

Some authors, such as Richard Kunin, M.D. and Michael Lesser, M.D., feel that the metabolism of cholesterol, which uses many vital nutrients, is the real problem. With adequate nutrient levels, reasonable amounts of dietary cholesterol will not cause the problems we are seeing. Our liver makes cholesterol, which we need for many functions such as the production of hormones (estrogen and testosterone), vitamin D, and bile. A natural feedback mechanism should reduce our production when we consume cholesterol-containing foods. There may be certain factors, yet unknown but possibly genetic and nutritional, that interfere with this feedback mechanism. B vitamins, vitamins C and E, magnesium, manganese, and zinc are all needed for cholesterol metabolism, and if these are low, this waxy fat cannot as easily get into the cells to function and sludges around in the blood, clogging up our vessels. This is rather like the process in adult diabetes, where the sugar cannot get into the cells and stays in the blood, causing problems.

In Mega Nutrition, Dr. Kunin suggests that the rapid rise in CVD was associated with three important dietary changes besides an increase in fat intake that were as significant as or even more significant than cholesterol. First was the refining and milling of flour which removed many of the nutrients that are important to cholesterol metabolism. Second was the use of chlorinated water which was popularized and spread throughout the country. Chlorine tends to bind and reduce levels of vitamin E which acts as an important protector of the vascular lining. Third, homogenized milk also hit in the 1940s. Homogenization changes the fat composition of milk so that it is not as easily metabolized and passes more readily through the liver. This, I believe, is a big factor in the increase in CVD.

These theories have some backing, but are not generally accepted. More research is needed to verify that we can still eat a reasonable amount of high-fat and high-cholesterol foods such as eggs, meats, milk, and butter, and still not develop CVD, as long as our diet is nutrient-rich and meets all of our needs. Until then, I believe that there is more than enough research evidence to prove that eating a diet low in fat, especially saturated fat, and cholesterol, along with the other changes that I suggest, is still the best thing to do. We still need fats in our diet, but mainly the natural essential fatty acids found in nuts and seeds, fish, and grains and beans. These oils are necessary for many vital functions and also help release bile products from the liver and gallbladder. Bile is made from cholesterol and thus is one of the ways to eliminate cholesterol from the body.

Cholesterol is part of many of the foods that omnivores eat. It is contained only in animal foods, such as meats, eggs, and milk products. The average daily intake in the United States is 500 mg. for men and about 350 mg. for women. Women are somewhat protected from CVD during their child-bearing years by their female hormones. The new suggested maximum for cholesterol intake is 300 mg., not much more than contained in one egg yolk (275 mg.). It is probably ideal, especially for those at risk for CVD, to consume less than 150 mg. of cholesterol daily. That is the reason for the big push to a more vegetarian diet. (A strict vegetarian diet, meaning no eggs or milk products, can sharply reduce an elevated cholesterol level in one month, possibly as much as 100 mg./dl. (deciliter), or 100 mg. percent.)

Cholesterol is easy to absorb and hard to eliminate. It appears that the higher our blood cholesterol level, the greater our risk of CVD. Below 180 mg. percent poses a low risk; 180?200 mg. percent is a good range; over 200 mg. percent clearly increases our CVD risk, while over 250 mg. percent gives us a high risk. (LDL and HDL levels are also important within the total cholesterol value; see discussion below.) The average adult has a blood cholesterol level between 200 and 220 mg. percent. So there is work to be done. There is no known deficiency disease with cholesterol; many people apparently do well with little or no cholesterol intake. The body still makes it, though with certain chronic illnesses or liver impairments, blood cholesterol levels may fall to very low and probably functionally deficient levels. Cholesterol helps in tissue repair and other important functions mentioned previously.

Many doctors feel comfortable working with the total cholesterol value alone. Reducing it through smoking cessation, control of diabetes, hypertension, or obesity, dietary changes, or exercise programs can offer some security in disease prevention. It is now known that even a small increase in cholesterol can lead to a marked increase in coronary disease and heart attacks; the main research studies suggest that every 1 percent we lower a high cholesterol, we reduce our heart disease risk by 2 percent. So even mild decreases in cholesterol are helpful.

In recent years, more practitioners are using the cholesterol subfractions?HDL and LDL (VLDL may also be significant). These represent lipoproteins, or fat-protein molecules, that carry the nonimmersible fats through the blood. The high-density lipoprotein (HDL) carries cholesterol back to the liver from the bloodstream and is thought to be protective by taking the extra cholesterol out of the blood. Low-density lipoproteins (LDLs) transport cholesterol through the blood to the cells and usually comprise most of the blood cholesterol. Very low density lipoproteins (VLDLs) also keep cholesterol in circulation and may contribute to atherosclerosis. The total cholesterol/HDL ratio and/or the LDL/HDL ratio can be observed as a relative measurement of CVD risks.

Smoking, being sedentary, and consuming saturated fats in the diet lower protective HDLs. Exercise, a high-fiber diet, and alcohol increase HDL, though alcohol also produces irritating effects on the liver and vascular system, and may increase total cholesterol. Increased LDL levels can be caused by increased consumption of saturated fats and sugar, deficient levels of vitamin C or chromium, and high copper or iron levels. The various fats have different effects on cholesterol. Saturated fats lead to more LDL and VLDL. The monounsaturated fats tend to have a neutral influence on cholesterol levels, while the polyunsaturated fats tend to lower total cholesterol but may also likewise lower the good HDLs.

Elson M. Haas, MD is founder & Director of the Preventive Medical Center of Marin (since 1984), an Integrated Health Care Facility in San Rafael, CA and author of many books on Health and Nutrition, including ...more