8.4: Prevention

Prevention relies on understanding the causes and development of diseases like atherosclerosis. This requires extensive studies of the subtle interplay between genetics and environment and how a normal cell works. Discovering how a cell makes cholesterol and how it takes in cholesterol from the blood via LDL receptors markedly advanced the understanding of the disease process. Think of how hard it would be to keep a car in good working order—or diagnose or fix a problem—if we didn’t know how cars work.

We can’t change our gender or genetics, but we can alter other risk factors. Atherosclerosis develops over many years, so even a modest reduction in its progression delays the onset of symptoms. Modest changes starting at age 20 might be enough to delay by 10+ years a heart attack or stroke that might have happened at age 60. This same logic applies to early detection and treatment of high blood pressure to delay an outpouching and rupture of a blood vessel. The three most significant risk factors that can be altered are smoking, high blood pressure, and high LDL-cholesterol.

Smoking

It goes without saying that smokers should quit smoking or smoke less (nonsmokers should avoid breathing other people’s smoke). It’s very difficult to quit smoking because nicotine is highly addictive (more so in some people than others). Nicotine chewing gum, inhalants, or skin patches, together with behavior modification techniques can help.

Studies indicate that the risk of a heart attack falls significantly within a year after quitting. Some risks fall immediately, e.g., those associated with the constricted blood vessels caused by nicotine and the reduced blood-oxygen due to the carbon monoxide inhaled in smoke.

Blood Pressure

Treating high blood pressure before the onset of symptoms plays a big part in preventing heart disease and stroke.* Adults should have their blood pressure checked regularly. High blood pressure has both genetic and environmental components. There are effective treatments, including medications.

Table 8-2: Lowering Risk for Heart Disease

If you have high blood pressure and are overweight, weight loss may, in itself, normalize blood pressure. (Obesity also raises the risk of diabetes, which more than triples the risk of dying from heart disease.) If you can’t get down to a normal weight, maintaining a loss of even a few pounds can help. If you can’t do this, try to keep from gaining more.

Psychological stress can cause high blood pressure, but at least some of the added risk can be from ways in which people cope with stress, e.g., smoking, drinking, over-eating. Someone who is stressed and has high blood pressure certainly is advised to take measures to lower stress. There are, of course, many good reasons for keeping stress (and body weight) to normal levels, whether or not a person is prone to high blood pressure.

Some people with high blood pressure can lower their blood pressure by limiting sodium intake, which comes mostly from salt.** The salt comes mainly from fast foods, chips, processed meats, olives, crackers, etc. (read your labels).

The average daily sodium intake in the U.S. for those age 1 and older is about 3,400 mg, with intake ranging from about 2,000 to 5,000 mg. On average, the higher the sodium intake, the higher the blood pressure. The 2020-2025 Dietary Guidelines for Americans (see Chap. 4) recommend limiting daily sodium to 1,200 mg for ages 1-3, 1500 mg for ages 4-8, 1800 mg for ages 9-13, and 2,300 mg for ages 14+.

Salt restriction to treat high blood pressure works for some people. But it’s unclear if follow ing a low-salt diet prevents high blood pressure from developing in the first place. High blood pressure is more common and tends to rise with age in populations with a high-salt diet, so it’s thought that a high-salt diet brings to light genetic susceptibility. There’s also a strain of rats that develops high blood pressure only when fed a high-salt diet, suggesting that there are such “strains” of people.

Some people simply do not develop high blood pressure despite eating a lot of salt, presumably because they don’t have the genetic tendency. But most people don’t know whether they have the genetic tendency, and there’s no known advantage to consuming excess salt, so it’s considered prudent to limit salty foods.

Diets rich in vegetables, fruit, and low-fat dairy products can be helpful in preventing and treating high blood pressure. Such diets are rich in magnesium, calcium, and potassium. Low intakes of these minerals may increase the risk of high blood pressure, perhaps by increasing salt-sensitivity.

Alcohol intake should not be excessive. There’s substantial evidence that more than two drinks a day raises blood pressure and also raises the risk of a hemorrhagic stroke independently of high blood pressure. One drink has about ½ oz alcohol, e.g., a 12-oz bottle of beer or wine cooler, 5 oz table wine, 1 jigger (1½ oz) vodka, rum, whisky, or gin.

^{*High blood pressure can also directly damage the kidney and heart. Think of the strain on the pump (heart) and filter (kidney) in a water filtration system with excessive pressure.
**5 grams (5000 mg) of salt (NaCl) is about 1 teaspoonful. Sodium chloride (NaCl) is 40% sodium. So a teaspoon of salt has about 2000 mg sodium. See Chap. 3 for how to calculate this.}

Blood-Cholesterol

Adults age 20 and older are advised to check their blood-cholesterol regularly. A consensus of the National Cholesterol Education Program is: total blood-cholesterol of less than 200 mg/100 ml is desirable; borderline high is 200-239; high is 240+. People who are high (or borderline with other risk factors) should have their LDL and HDL checked (these tests cost more).

It can be hard to lower LDL(bad)-cholesterol because the body makes cholesterol. As mentioned in earlier chapters, cholesterol is an essential molecule needed as a part of cell membranes and as starting material for essential substances like bile acids and hormones.

The body is limited in ways to get rid of cholesterol. Unlike triglycerides, for example, the body can’t dispose of cholesterol by breaking it down to carbon dioxide and water.

How much cholesterol a cell makes depends on the amount already in the cell. If there’s plenty of cholesterol, cells make less. If there isn’t enough, cells make more. This is why people with familial hypercholesterolemia have such high LDL. Their cells, lacking the proper LDL-receptors to take in LDL from the blood, make cholesterol unabated because cholesterol can’t get in to hamper production.

LDL can often be modified by diet within a few weeks. But people vary widely in how they respond to diet. Amounts of saturated and trans fats, and fiber in the diet have the biggest potential effect. Even if blood-cholesterol is at the recommended level, lowering LDL seems to further lower the risk of atherosclerosis. Also, LDL-cholesterol tends to rise as one gets older, so a “prudent diet” may help keep it from rising.

Saturated and Trans Fat

Saturated and trans fat (see Chap. 5) in the diet increases LDL in the blood, possibly by lessening the uptake of cholesterol into cells via LDL receptors. This effect is quite consistent, although some people are much more responsive than others.

We’re advised to keep trans fat intake as low as possible and limit the saturated fat in our diet to less than 10% of our calories (Chap. 4). Saturated fatty acids don’t affect LDL equally. The saturated fatty acids lauric (12:0), myristic (14:0), and palmitic (16:0) increase LDL more than other saturated fatty acids. Food, however, has a mixture of fatty acids (Table 5-3).

As we learn more about differing effects of particular fatty acids, food companies may manufacture and use fats with only one kind of fatty acid or another to get the desired sensory effect in their food products without getting the undesired effect of raising blood-cholesterol. If food companies in fact do this, we can expect this information to be touted in advertisements for the food product.

To reduce saturated fat intake, replace fatty cuts of meat with poultry, fish, or lean cuts of meat; drink fat-free or low-fat milk instead of whole milk. Butterfat (as in whole milk, ice cream, cheese, and croissants) is a big source of saturated fat in the American diet. Trans fat comes mostly from foods that contain partially hydrogenated oils (Chap. 5).

Monounsaturated and polyunsaturated fat generally lowers LDL. Again, some people are more responsive than others.

Fiber

Eating more fiber-rich foods can help lower LDL. Plant foods have a variety of fibers, some of which lower blood cholesterol. Animal foods do not contain dietary fiber.

As to their action in the body, fibers can be roughly categorized by whether they dissolve in water. Soluble fibers (those that dissolve in water) can help lower blood cholesterol. In contrast, insoluble fiber can help prevent diverticulosis, and constipation (Chap. 6). Cellulose (an insoluble fiber), for example, adds bulk to the stools and can thus help prevent constipation, but doesn’t appear to help lower blood-cholesterol.

Plant foods have a mix of soluble and insoluble fiber. Some foods that are particularly rich in soluble fibers are oats, beans, and fruits. You get a lot of soluble and insoluble fiber by following the advice to eat lots of fruits, vegetables, and whole grains (Chap. 4).

There are at least three ways in which some kinds of fiber might lower blood cholesterol:

• Lessening the amount of bile absorbed from the small intestine. Bile acids are made in the liver from cholesterol and are secreted into the upper part of the small intestine to aid fat-digestion (Chap. 6). Bile acids are then absorbed from the lower part of the small intestine and recycled (via the blood) back to the liver to be used again in bile. Soluble fiber (e.g., pectin) hampers this absorption of bile acids, so less is returned to the liver, and the liver uses more blood-cholesterol to make bile acids to replace what’s lost in the stool. A drastic treatment to lower blood-cholesterol is to lessen the absorption of bile acids by surgically bypassing part of the lower small intestine.
• Interfering with the absorption of dietary cholesterol in the small intestine. Less cholesterol is absorbed when eaten in the same meal as some kinds of fiber.
• Interfering with the body’s production of cholesterol. Colon bacteria break down some kinds of fiber into products that are then absorbed into blood and may hamper cholesterol production.

Dietary Cholesterol

Cholesterol in the diet has much less of an effect on LDL than trans or saturated fat. Again, individual responses vary. If the body makes more cholesterol in response to less in the diet, blood-cholesterol may not go down.

Cholesterol isn’t required in the diet, and some people can benefit from eating less. The advice had been to limit dietary cholesterol, which mostly means limiting eggs (the yolk is rich in cholesterol). Other rich sources of cholesterol, e.g., organ meats like liver and brain, aren’t widely eaten.

However, eggs have many practical advantages because they are inexpensive, keep a long time in the refrigerator, and are easy and quick to cook. Also, the softness of eggs is desirable for many people, e.g., those with missing teeth or ill-fitting dentures. These are important considerations, especially for the poor and elderly. For many of these people, eggs are an important source of nutrients.

There isn’t much research on the benefit—or lack of benefit—of lowering dietary cholesterol in older adults. Studies showing modest benefit are mostly of middle-aged men and women. The latest Dietary Guidelines for Americans (2020- 2025) no longer advises that the general, healthy population restrict dietary cholesterol.

Foods have a variety of nutrients, and individual foods have their pluses and minuses. The concern isn’t only atherosclerosis, but overall health. For people who eat a lot of eggs for such reasons as they simply can’t get to the grocery store very often, reducing or eliminating eggs could have a negative effect on their diet and health. As discussed in Chapter 4, it is one’s overall diet—not an individual food itself—that tends to be “good” or “bad.”

HDL-Cholesterol

Low HDL(good)-cholesterol raises the risk of atherosclerosis. Some people are genetically endowed with extraordinarily high HDL, but this is unusual. This genetic aberration seems to protect against atherosclerosis and is linked to longevity. (There is, however, another genetic aberration that causes high HDL, but without the protection against atherosclerosis because the HDL doesn’t function properly.)

Most of us have either normal or low HDL. Smoking, lack of exercise, and obesity are all linked to low HDL. Of course, quitting smoking, exercising, etc., have additional health benefits besides raising one’s HDL.

Moderate alcohol intake is linked to higher HDL and less heart disease in middle-aged men and postmenopausal women. The guideline If you drink alcoholic beverages, do so in moderation (Chap. 4) applies here.

It’s not advised that people who don’t drink start drinking simply to raise their HDL. As noted earlier, excessive alcohol is linked to high blood pressure and a higher risk of hemorrhagic stroke. (Alcohol can also damage the liver and increase the risk of cancer.)

Although moderate alcohol intake can lower the risk of heart attacks, this doesn’t necessarily mean it improves overall health or the overall death rate. The French, for example, drink more alcohol and have less heart disease, but have more alcohol-associated cancers and more cirrhosis of the liver.

There’s only a subtle difference, but it may be more accurate to say that low HDL is linked to higher risk of heart disease, than to say that a high HDL is linked to lower risk. We repeatedly hear that exercise increases good cholesterol and that people with high levels have a lower risk of a heart attack. This can mislead us into thinking that more and more exercise will lead to such high HDL that we can overcome other risk factors.

Instead, if we’re told that a sedentary lifestyle lowers HDL, it’s easier to see that moderate exercise is beneficial because it helps maintain normal HDL levels. Added exercise (beyond moderate) doesn’t proportionately raise HDL. Furthermore, low HDL isn’t as much of a risk factor as is high LDL, smoking, or high blood pressure. While regular exercise is important in lowering the risk of heart disease, its importance shouldn’t be either under or overemphasized.

In 1984, Jim Fixx, the avid long-distance runner and popular author of books and articles on running, died suddenly at age 52 of a heart attack while on his way back from a run. People were shocked and dismayed, especially runners. At age 32, he gave up a 2-pack-a-day smoking habit. At age 35 (the age his father had a first heart attack), he started running, and got to a normal weight by losing more than 50 pounds.

At age 43 (the age his father died of a heart attack), he took a leave of absence from his high-stress job as a magazine editor in New York City to write The Complete Book of Running. The book was an immediate success, earned him over a million dollars, and allowed him to quit his job.

Jim Fixx apparently didn’t have a regular physician. An autopsy showed severe heart disease, including signs of earlier, mild heart attacks. His father’s early death from a heart attack was certainly a strong risk factor. The question is what his fate might have been if he had had regular medical care and treatment, or hadn’t been running 10 to 15 miles a day.

Omega-3 Fatty Acids

Eating fish is linked to a lower risk of heart disease. Omega-3 fatty acids (Chap. 5) in fish are thought to be what lowers risk. Only small amounts are found in vegetables and meats (see 18:3 and >18:3 fatty acids in Table 5-3); the main source is fish.

The native Eskimo diet includes a lot of fish, seal, and whale, and is very rich in omega-3 fatty acids. Eskimos have a low incidence of heart disease, even though their diet is high in cholesterol and total fat (mainly polyunsaturated).

Omega-3 and omega-6 fatty acids are essential nutrients (Chap. 5) that are needed as starting material to make substances like prostaglandins, which have a wide array of effects on such things as acid secretion in the stomach, allergic response, and constriction and dilation of blood vessels.*

Many of the substances made from omega-3 or omega-6 fatty acids are counterbalancing, e.g., either lessen or enhance the blood’s ability to clot. Thus, the relative amounts of omega-3 and omega-6 fatty acids in the diet can tip the balance. If omega-6 predominates (as in the American diet), the body makes more of its products. If omega-3 predominates (as in the Eskimo diet), products made from omega-3 predominate.

Eating foods rich in omega-3 fatty acids seems to tip the balance toward a lower risk of heart disease as shown by widened arteries, a reduced ability of platelets to cluster, lower blood pressure, and higher levels of TPA (called Activase when made by biotechnology)—the substance in blood that triggers the breakdown of clots.

Besides lessening the formation of clots that might block narrowed arteries, omega-3 fatty acids may retard the development of atherosclerosis itself. Studies of hundreds of men followed for many years have found that men who eat fish regularly have a lower rate of death from heart disease. (Keep in mind that linking “eating fish regularly” to fewer deaths from heart disease doesn’t prove that it’s omega-3 fatty acids in fish that protect. It might be other substances in fish, or it might be that “eating fish regularly” is simply a marker for other healthful aspects of a person’s life.)

It seems that the American diet would be healthier with fewer foods rich in omega-6 and more foods rich in omega-3. On the other hand, the native Eskimo diet might be healthier with less omega-3 and more omega-6; In fact, the Eskimos’ reduced ability to form blood clots was noted long before the discovery of the relationship to omega-3 fatty acids.

Gontran de Poncins, a French aristocrat who lived among the Eskimos, wrote in his 1941 book Kabloona:

Manilak and his wife both began to suffer from nosebleeds, a thing common among the Eskimos and likely to be serious. I have known it to go on for several days, and men have died among them as the result of the loss of blood. These two bled for hours and left a stain on the snow behind the gliding sled.

Nosebleeds are a side effect of a high intake of omega-3 fatty acids, and Eskimos eating a native diet are prone to hemorrhage and hemorrhagic stroke. One suspects that omega-3 in the native Eskimo diet is excessive.

The American Heart Association advises eating at least 2 servings/week of fish (particularly oily fish like salmon, tuna, mackerel, herring, trout). Fish-oil supplements and omega-3 fatty acid capsules are classified as dietary supplements rather than drugs, so keep in mind that they aren’t subjected to the strict regulations of content, safety, purity, dosage, etc., established for drugs (and food additives).

^{*For discoveries relating to prostaglandins, Drs. Bergstrom, Samuelsson, and Vane shared a Nobel Prize in 1982.}

Medication

Drugs are used as a preventive measure in people who don’t have symptoms of heart disease. For example, drugs to lower blood pressure are prescribed for those who have high blood pressure but no symptoms (high-blood pressure not only raises risk of heart attack and stroke, but can damage the heart and kidneys). Similarly, high blood-cholesterol is treated with cholesterol-lowering drugs.

A number of drugs lessen the formation of blood clots, e.g., aspirin, warfarin, dicumarol, and newer (and expensive) drugs like Pradaxa. Nicotinic acid (niacin)* is used in huge doses (1000 to 9000 mg/day) as a drug to lower LDL-cholesterol. Niacin is a B-vitamin (adult RDA =14-16 mg/day), but functions as a drug when taken in such large doses.

Aspirin and nicotinic acid (and capsules of omega-3 fatty acids) can be bought without prescription, leading many people to use them casually.† Drugs, including nutrients used as drugs, have side effects that must be taken in consideration in weighing benefit vs. risk.

For example, a study of male physicians, showing that a single aspirin taken every other day lowered risk of heart disease, was widely publicized. As discussed in Chapter 2, what wasn’t publicized was that the physicians were carefully selected so as to exclude those whose health might be endangered by aspirin (e.g., people with ulcers or people at risk of hemorrhagic stroke).

As another example, large doses of nicotinic acid can cause irregular heartbeats and damage the liver; physicians prescribe liver-function tests during treatment. Milder side effects include itching and hot flushes in the skin, and digestive upsets.

Some drugs, such as cholestyramine (Questran) and colestipol, are used because they combine with bile acids in the intestine and promote the excretion of bile products. This method of lowering blood-cholesterol was discussed earlier in relation to the dietary fibers that promote the excretion of bile products.

“Statin” drugs (e.g., lovastatin) lower the body’s production of cholesterol and are among the most effective in lowering blood-cholesterol. Drugs are sometimes used in combination, e.g., a drug to promote excretion of bile products plus a drug that lowers cholesterol production.

Despite the effectiveness of drugs to lower risk of heart disease and stroke by lowering blood cholesterol and blood pressure, many people don’t take the drugs prescribed by their physicians. Also, many people don’t get their blood-cholesterol or blood pressure checked regularly.

Many of these drugs are generic and inexpensive, so the problem is often motivation. High blood-cholesterol itself has no symptoms, and many people don’t have overt symptoms of high blood pressure. Also, the drugs can have side effects, causing people to quit. Too often, the motivating factor for taking the drugs is having a heart attack or stroke—and surviving to meticulously take the drugs to prevent another one.

^{*The B-vitamin nicotinic acid is called niacin to avoid confusion with nicotine, the addictive drug in tobacco. Another form of niacin called nicotinamide or niacinamide doesn’t have the same effect as nicotinic acid in lowering LDL.
†Several dietary supplements, e.g., ginkgo, have anti-clotting effects. This is why it’s important to let your physician know which supplements you take. They can potentiate or interfere with other drugs, affect blood clotting during surgery, etc.}