THE CHOLESTEROL MYTH

"The anatomy of any myth
is the anatomy of the men
who believed in it and suffered by it."

MURRAY KEMPTON, "A Prelude," Part of Our time (1955)

Cholesterol is almost a household word and we all know how bad cholesterol is for our health. Or do we? The public bias against cholesterol is well established and hardly anyone would believe me if 1 said that the bad effects of cholesterol have been blown out of proportion.

The fact is, cholesterol is a very useful fat, serving as a precursor to various essential hormones and vitamins. The cholesterol in our skin prevents us from absorbing many dangerous chemicals in our polluted environment and also helps restore the water in our body to prevent dehydration. Cholesterol also acts as a potent antioxidant, protecting the body from cancer causing free radicals. Finding anything else floating in the blood half as good as cholesterol would be quite a task.

There is no denying that cholesterol is associated with heart disease but not in the way we generally believe. Not knowing what cholesterol is and does, can make our efforts to reduce risk of heart disease less meaningful.

Cholesterol is found abundantly in foods (table 8. 1). The highest concentration of cholesterol occurs in the organ meats and egg yolk. Organs such as liver, kidney and brain are extremely high in cholesterol. Most other foods have somewhat comparable levels of cholesterol.

TABLE 8.1
CHOLESTEROL CONTENT OF COMMON Food)s

Unlike the essential fatty acids and Proteins, cholesterol need not be supplemented in our diets since it is synthesized by the body (about 1.5 grams per day, if no cholesterol is supplied in the diet). Normally we have about 10 grams of cholesterol (in various forms)floating in our blood at all times. To control the level of cholesterol, our body increases or decreases production of cholesterol; however, there are limitations in the body's ability to adjust levels of cholesterol. It takes about five days for a 50 percent turnover or consumption of floating cholesterol. When diets supply excessive cholesterol, the body cuts down its cholesterol production units, and the levels of cholesterol rise only if.body cannot dispose off excessive cholesterol

Therefore taking cholesterol-free diets may not always lower cholesterol levels in the blood. In fact, some cholesterol in our diet is recommended to keep cholesterol producing systems in the body working at a lower efficiency. The American Heart Association recommends no more than 300 mg of cholesterol per day for men and 225 mg per day for women. So, there is no reason to use those expensive "cholesterol-free" bland foods.

Before we plan to reduce floating cholesterol, we must recognize why the body needs cholesterol in the first place. One such need is the antioxidant, or cancer protection action of cholesterol. If these needs can be satisfied by alternate means, the body will reduce floating levels of cholesterol itself. Generally, if the level of antioxidants such as vitamins A, E, C and some Bs is sufficient in the body, cholesterol levels will be reduced.

CHOLESTEROL AND BLOCKING OF ARTERIES

The connection between cholesterol and plaque formation and hardening of the arteries is a well established one. High levels of cholesterol cause head attacks-but not in all individuals, It is easy to make cholesterol a scapegoat but cholesterol is not harmful until combined with other fatty elements in the blood, at which time it demonstrates its vicious characteristics. However, before we get into these fine deliberations, let's examine the evidence connecting cholesterol to heart disease.

The most conclusive study regarding the role of cholesterol in heart disease was released in 1984 by The U.S. Lipid Research Trials, which showed that a 14 percent decrease in the blood cholesterol levels resulted in a 19 percent reduction in the incidence of heart attacks. This reduction was achieved by using a drug called cholestyrarnine, which helped remove cholesterol from the diet by bonding to it and making it unabsorbable. Another study in 1978 showed that a 9 percent decrease in the cholesterol level resulted in a 25 percent decrease in the incidence of nonfatal heart attacks but no reduction of fatal heart attacks. In 1981, a study from Norway showed that a simple modification in diet resulted in a 40 percent reduction in deaths from coronary heart disease.

A low fat diet would reduce not only cholesterol but also many other types of fats such as omega-6 acids etc, So, there is sufficient evidence now which suggests that more than just cholesterol is the culprit in our diets.

It is now widely accepted that low density lipids (LDL) are responsible for damage to arteries and head whereas, the high density lipids (HDL) prevent forrnation of plaques. Cholesterol of both types is found in the blood. There is sufficient evidence in the medical journals to prove the beneficial effects of HDL. For example, women experience fewer heart attacks than men; one of the several reasons for this is the higher levels of HDL in women. Exactly how the HDL and LDL differ in the formation of plaque is not fully understood. It is suspected, however, that the LDL, being larger in size (figure 2.2), do not pass through the arteries readily and get trapped, causing infiltration of the arteries (figure 5.1). The HDLS, which are smaller but heavier particles, can easily pass through and can even help "lubricate" the flow of blood fats, much like rolling a heavy object on a ball bearing.

So, the culprit in our blood is not only cholesterol but other types of fats as well; even cholesterol can be good when it is part of the HDL. therefore our goal should be to increase, not decrease the fat levels in the blood which are of high density type and decrease only the LDL. The risk of heart disease increases dramatically when the concentration of high density cholesterol decreases (table8.2)

TABLE 8.2
RISK OF HEART DISEASE AND HDL LEVELS

% Cholesterol as HDL

Slight increase in HDL, such as from 20 percent to 25 percent reduces the risk of heart disease by 50 percent for men; women, who are more resistant to heart disease require greater change, from 22 to 33 percent to cut the risk of heart disease to the same degree. When it comes to increased risk due to lowering of HDL or increase in total cholesterol, men can cope with more total cholesterol than women. A three-fold increase in risk to heart disease develops when HDL levels drop to eight percent of all cholesterol in blood for women and four percent for men.

The risk of heart disease should, therefore, be measured in terms of the ratio of total cholesterol to HDL rather than the total cholesterol. For example 9 you may have above average level of cholesterol but if a substantial percentage of it is present as HDL then it is better than having a lower total cholesterol. Therefore, you should try to increase your HDL instead of worrying too much about the total cholesterol. One way to do it is by exercise.

Physical aerobic exercise increases the concentration of HDL and reduces the concentration of LDL. Joggers have considerably higher levels of HDL, which depends more on the distance covered rather than on the speed. The current trend toward walking instead of jogging is definitely in the right direction.

No drug is currently available to selectively reduce LDL or increase HDL levels. When diet modifications are used, they most likely alter the total fat levels rather than a particular type. One diet component that has significant effect on blood fat levels is the polyunsaturated vegetable oils, which reduce both the LDL and HDL levels and therefore the ratio of HDL may not change (table 8.2).

Several gimmicks are also on the market, such as the use of lecithin which promises to reduce Cholesterol and the risk of heart disease. None of these work; some can even be very harmful since they can upset the balance of various chemicals in the blood.

FISH AND CHOLESTEROL

The only dietary tool for reducing blood fats, especially the LDL, while maintaining high levels of HDL, is the use of fish. An interesting study, in this regard, was reported in 1984, when 100 subjects were given two teaspoons of fish oil twice daily with food. After 24 months the blood fats were measured to reveal a most startling favorable change in the blood fats (table 8.3).
TABLE 8.3
EFFECT OF FISH DIET ON 13LOOD CHEMISTRY

The fish diet not only reduced the dangerous triglyceride and cholesterol levels but increased the beneficial HDL level, a feat never before achieved by diet or drugs. Also altered, the study found, was the platelet count and their activity, both responsible for causing plaques to form. This study established, beyond any doubt, the beneficial effect of fish in bringing the most favorable changes in the blood chemistry. We could not ask for a better medicine, if one existed, to combat heart disease.

A diet of fish or supplementary fish oils are also highly recommended for those who consume high cholesterol diets habitually. An interesting study was reported by Dr. Paul Nestel in 1986, in which subjects consuming large quantities of egg yolk showed no change in their cholesterol level if their diet was supplemented with fish oil. Therefore, the therapeutic value of fish in reducing cholesterol levels is firmly established.

Critics of the above recommendation state that not all types of fish can be eaten in large quantities because of their high cholesterol content. This misconception must be clarified. Information in Chapter 2, showed that there is no fish, regardless of its habitat, which can be labeled high in cholesterol. For example, shellfish such as shrimp, lobster and crab, the most commonly criticized fish, have much lower cholesterol than generally assumed.

Shell fish got a bad name several years ago when an erroneous report was made about their cholesterol content. The mistake was that cholesterol and like substances were totaled and reported as cholesterol. We now find oysters, clams and scallops to have about 50 percent less cholesterol than previously reported, so there is no reason why people can't eat them.

LIQUID CHOLESTEROL

Several new studies on the effects of fish on heart disease were presented at the annual meeting of the American Heart Association in November 1986. One examined the nature of the fatty deposits formed when omega-3 acid concentration is high in the blood. The fatty deposits or atheroma are more "liquid" and have lesser ability to clog arteries when fish is eaten frequently. The low freezing quality and lubricating ability of omega-3 acids is responsible for this change in the nature of fatty deposits.

MISTER FIXX

Jogging might be labeled the number-one pastime for health-conscious Americans and Jim Fixx was certainly its chief advocate. His book, Running, headed the best seller list for many months. The man practiced what he preached. He was a slender and lean man who ran every day and kept his cholesterol, triglyceride and other fat levels at below normal levels, but he died of a sudden heart attack with massive atherosclerosis while running. He died young and the nation was shocked. Had we understood the relationship between the float. ing cholesterol or fats and atheroselerosis and heart attacks we would have been less surprised.

Nothing is a simple as it seems and certainly not the stark advice to keep cholesterol levels low to help prevent heart attacks. Not only is it the cholesterol but a lot of other lipids in the blood which contribute to head disease. It is the tendency of these lipids to ac. cumulate that causes atherosclerosis and not just their mere existence in the blood. And what causes them to form a deposit is highly individualistic. Many people can survive with high concentrations of cholesterol in blood without ever developing atherosclerosis while keeping our blood cholesterol levels way below normal according to polpulation average.

Cholesterol has become almost a dirty word, yet the truth is, cholesterol is essential chemical for body growth which can also be prevent hearth attacks and artherosclerosis. Unfortunately, the consumer industry is often too quick to capitalize on these "emerging" scientific concepts, causing us to go from one extreme to the other. You see all around you, product which are "low in cholesterol." "free of cholesterol" and which have "no cholesterol." You may be consuming less cholesterol, but this is not necessarily safe for your heart.

If a diet promotes plaque formation, it is immaterial whether it is a low or high cholesterol diet. For example we know that vegetable oils help reduce cholesterol levels, but do they reduce incidence of atherosclerosis and heart attack? Probably not. A large number of processed foods appear safe to a naive consumer because they are free of cholesterol, but are they less likely to cause atherosclerosis? Probably not.