HIGH BLOOD CHOLESTEROL

Another major risk factor for heart disease is high serum cholesterol or, simply put, an excessive amount of cholesterol in the bloodstream. But what exactly is cholesterol? And what constitutes “excessive”?

Cholesterol is a waxy lipid, or fat, that is produced by the body and found in the cell membranes, nerve linings, and blood. Serum cholesterol is measured in milligrams per deciliter of blood; if your cholesterol level is 220, you have 220 milligrams of the fatty substance for every tenth of a liter of blood.

Less than half the cholesterol in your body comes from the foods you eat. The rest is manufactured in your liver and other body organs. After it is synthesized, the cholesterol is released into the bloodstream, where it is carried to different destinations.

Like high blood pressure, high blood cholesterol can be a silent killer, causing your body injury while presenting no symptoms. So it is important to have your cholesterol measured at least every two years. According to the National Institutes of Health, your blood cholesterol should not exceed 200. Readings of 200 to 240 are considered borderline. A reading above 240 is categorized as high and considered a significant cardiac risk factor (see Table 3.1).

Just how significant a factor cholesterol is depends on your other risk factors. Let’s say, for example, that your cholesterol level is 240. If you are a fifty-year-old man who smokes a pack of cigarettes a day, is obese (27 percent body fat or above), rarely exercises, has a blood pressure of 140/95, and whose father died of a heart attack at age fifty-nine, you are in big trouble.

If, however, your blood cholesterol is 240 but you are a trim, nonsmoking, fifty-year-old woman, with normal blood pressure and healthy, elderly parents, your risk of having a heart attack is much lower. Still, you would be in an even better position if that 240 were reduced, for it is no longer deniable that lowering your cholesterol reduces your chance of having a heart attack. The Japanese are an impressive illustration of the strong influence of cholesterol in bringing about heart attacks. In Japan, the average blood cholesterol is very low, and heart attack rates are correspondingly low. This is true even though smoking is common and blood pressure tends to be higher than among Americans. But ethnic Japanese who live in America and eat the high-fat American diet have higher cholesterol levels and more heart attacks than their relatives eating the Japanese diet.

HDL and LDL: “Good” and “Bad” Cholesterol

Actually, we have learned recently that the cholesterol issue is a bit more complicated than knowing your total blood cholesterol. There are several types of lipoproteins (transporters of cholesterol), the most important of which are HDL (high-density lipoprotein) and LDL (low-density lipoprotein). They act in very different ways, and with very different consequences for your health.

It turns out that LDL delivers cholesterol to the walls of the arteries, where it is deposited as plaque. Over time these fatty deposits accumulate, narrowing the arteries. The result is heart disease. However, HDL does just the opposite. It strips the cholesterol from arterial walls and carries it back to the liver, where it is converted to bile and then eliminated. So HDL actually reduces the total amount of cholesterol in the body. Generally speaking, the more HDL you have, the better off you are: 45 milligrams per deciliter is about average. Levels of HDL under 35 are considered risky, while figures of 55 and above provide greater protection against heart disease.

One way to think of the heart’s health is as a battle waged between the good guys, HDL, and the bad guys, LDL. When a person develops heart disease, the contest has been won by LDL. So, if you want to know how the battle is going in your own body, you should be most interested in the amounts of HDL and LDL rather than total cholesterol.

What seems most important is the amount of HDL relative to total cholesterol. This is sometimes expressed as the percentage of total cholesterol that is HDL, but more often it is put the other way, as the ratio of total cholesterol to HDL. In the first way of measuring HDL, the higher the number the better for you; in the second, the lower the ratio, the better. Table 3.2 shows a range of values and their associated levels of risk.

Let’s say your total cholesterol is 200 and your HDL is 44. That would give you a ratio of 4.5. This ratio means you have an average risk of developing heart disease. Another example: imagine that your total cholesterol is a desirable 180, but your HDL is only 30. This gives you a ratio of 6.0, which means that your risk is about double the average. If with the same total cholesterol your HDL were 60, then the ratio would be 3.0 and you would have about half the average risk.

                                       Shifting the Odds in Your Favor

There are two ways to change the ratio in your favor: lowering LDL or raising HDL. The best strategy, I believe, is a dual approach. Most doctors will tell you that it is easier to reduce LDL, by changing what you eat: cut down on saturated fats and increase the amount of dietary fiber you take in. The best way to reduce saturated fats is to limit the amount of red meat and dairy products you eat and replace highly saturated tropical plant oils (such as coconut and palm oil) with less saturated vegetable oils.

As for the amount of fiber we should be consuming, let’s look at the diet we humans evolved eating. A fascinating study of the diet of prehistoric people, originally published in The New England Journal of Medicine, indicates that they ate about 100 grams of fiber a day. Nutritionists, apparently resigned to modern reality, recommend that we eat at least 25 grams of fiber a day. But the average American diet falls far short even of this modest goal, containing only about 10 to 12 grams.

Vegetables such as carrots, broccoli, artichokes, peas, radishes, and collard greens and fruits such as apples, berries, figs, pears, and nectarines are particularly rich in dietary fiber. By the way, fiber has an added bonus: it protects against colon cancer.

The other way to shift the ratio in your favor is to increase your level of HDL. And this is much more easily done than most doctors believe. The key is contained in one eight-letter word: exercise.

Studies have shown that you must exercise for at least twenty minutes, three days a week, to get minimal results. But to raise your HDL significantly, all it takes is a little more: a total of only two to five hours a week, spread out over five or more days. We know that swimmers begin to raise HDL levels about six weeks into this kind of regimen.

Not long ago I discovered just how effective swimming can be in boosting HDL. In late 1990 I came down with a mysterious liver ailment after spending two weeks in the Amazon. The illness kept me bedridden for almost six months. At the end of that time, blood tests showed that my total cholesterol was 227 and my HDL was 49. That gave me a ratio of 4.6, meaning my risk of developing heart disease was just slightly above average. After recovering I began training again, swimming about five to seven hours a week.

Within a year my total cholesterol had improved only modestly, down to 209. But my HDL level had almost doubled, to 90. This changed my total cholesterol-to-HDL ratio to 2.3, which my doctor informed me was off the chart on the safe side.