What Causes Heart Disease? Part 1

Over the years, the debate on the role of cholesterol in the development of atherosclerosis and heart disease continues. When it was first proposed that high cholesterol increases heart attack risk, the medical establishment ridiculed the idea. However, decades of disputes changed the stance of the medical establishment, now the concept that high cholesterol causes heart attack has become a scientific consensus.
But many of today’s complementary medicine practitioners, who would have been early proponents of low-saturated fat diets, now question the association between cholesterol and vascular disease. This has become what is known as the "cholesterol controversy." The fact that confusion still exists over this straightforward medical principle helps explain why atherosclerotic disease remains today’s leading preventable killer.

While browsing through available scientific literatures and reviews on the topic, I came across an article by Dr. Larry Wilson, MD detailing important aspects in our understanding of the role of cholesterol in heart disease. The following is an exerpt of the article entitled "The Cholesterol Controversy" which I will present here in a three-part series.
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Medical authorities continue to recommend drugs and low-fat diets to reduce cholesterol. However, there is much more to the cholesterol story.

What Is Cholesterol?

Cholesterol is an essential body chemical, mostly synthesized in the liver. It is the precursor or raw material used to make the vital pituitary, adrenal and sex hormones. Cholesterol is also required to form vitamin D and bile acids. The liver makes about 2 grams of cholesterol daily, regardless of diet. Under stress, the body makes more cholesterol in order to make more adrenal or stress hormones.

Cholesterol is a mixture of compounds. These include high density lipoproteins or HDL, and low density lipoproteins or LDL. The latter contain lipoprotein-A, thought by some authorities to be important in the genesis of heart disease.

HDL, which is unoxidized cholesterol, is sometimes called ‘‘good cholesterol’’, while LDL, the oxidized form, is often termed ‘‘bad cholesterol’’. Blood laboratories often measure the ratio between the HDL and total cholesterol. 

Does Cholesterol Cause Heart Disease? 

The cholesterol theory of heart disease asserts that: 1) The risk of cardiovascular disease correlates with the serum level of cholesterol; and 2) Eating cholesterol-containing foods raises your cholesterol level. Let us explore this theory and alternative hypotheses in more detail.

About 100 years ago scientists noted that fatty deposits in the arteries often contain cholesterol. Of course, it was not known whether cholesterol deposits were the cause or the result of heart disease. Studies were done, including the large Framingham study, that found a definite correlation between high serum cholesterol levels and the risk of heart disease.

However, the picture is not as clear as it seems. The Framingham study found that LDL or oxidized cholesterol was more predictive of heart disease than total cholesterol. Also, the study could not correlate eating foods containing cholesterol and an increase in the blood cholesterol.

Furthermore, many studies from around the world do not support the simplistic idea that eating more cholesterol or saturated fat increases the risk of heart disease. In an interesting book, The Milk Of Human Kindness Is Not Pasteurized,(1) William C. Douglass, MD cites the following:

• The famous heart surgeon Michael Debakey analyzed 1700 patients with hardening of the arteries and found no correlation between blood cholesterol levels and the degree of atherosclerosis.(2)
• The New England Journal of Medicine reported that a group of Guinea natives whose diet is normally low in cholesterol were fed eggs to see how much the eggs would influence their cholesterol. There was no significant effect on cholesterol levels.(3)
• A study done by the American Cancer Society revealed that non-egg users has a higher death rate from heart attacks and strokes than egg users. This was a large and therefore convincing study involving over 800,000 people.(4)
• Eskimos living on a diet of mostly meat and fat, have low cholesterol levels (about 130mg) provided they stay on their native diet.
• The Masai tribe of Africa drink about 7 quarts of milk per day containing 60% saturated fat. Yet the average adult cholesterol level is 122.(5)
• The American Academy of Pediatrics is warning against the latest call for low cholesterol foods for children, since it is known that cholesterol is vital for children's growth

Many other studies show no significant effect on blood cholesterol from eating eggs or other cholesterol-containing foods. Several are reported in The New Vegetarian, by Gary and Steve Null. A study in France found that although butter consumption is much higher in Western than in Eastern France, the mortality from heart disease in Western France is almost half that of Eastern France.(6)

Before Western eating habits were introduced into the Eskimo population, they lived almost exclusively on animal meat and fat. Yet the incidence of heart disease was very low and cholesterol levels were below 200 mg.(7) Similar results were found in studies in the Soviet Union, India, and elsewhere.(8)(9)

The cholesterol theory of heart disease is very simplistic. It is like saying that duct tape wrapped around a damaged water hose is the cause of the hose damage. More likely, the tape - and the cholesterol - are the result of the damage, not the cause. In fact, two scientists, Brown and Goldstein, won a Nobel Prize in 1985 for their research into this theory. Cholesterol plaques are often there to protect a damaged artery. After all, a clogged artery is far preferable to a ruptured one. Elevated cholesterol is associated with heart disease, but may not be its cause.

References: 

1. Douglass, W.C., The Milk of Human Kindness is not Pasteurized, Copple House Books, Lakemont, Ga., 1985.

2. JAMA 189:655-59 (1964).

3. New England Journal of Medicine, 98:317 (1978).

4. Abrams, Journal Applied Nutrition, Vol. 32, #2, pp. 53-87.

5. Cardiovascular Disease of the Masai, Mann et. al.

6. Maclennan, R. and Meyer, F., Food and Mortality in France, The Lancet, 2 (1977): p. 133.

7. Ho, K.J. et al, Alaska Arctic Eskimo: Responses to a Customary High Fat Diet, American Journal of Clinical Nutrition, 25:1972, pp. 737-745.

8. Malhotra, S., Graphic Aspects of Acute Myocardial Infarction in India with Special Reference to Patterns of Diet and Eating:, British Heart Journal, 29:1967, pp. 337-344.

9. Prior, I.A. et al., Cholesterol, Coconuts, and Diet on Polynesian Atolls: A Natural Experiment, American Journal of Clinical Nutrition, 25:1972, pp. 737-745.

Risk Factors in Heart Disease

Extensive clinical and statistical studies have identified several factors that increase the risk of coronary heart disease and heart attack. Major risk factors are those that research has shown significantly increase the risk of heart and blood vessel (cardiovascular) disease. Other factors are associated with increased risk of cardiovascular disease, but their significance and prevalence haven't yet been precisely determined. They're called contributing risk factors.

The American Heart Association has identified several risk factors. Some of them can be modified, treated or controlled, and some can't. The more risk factors you have, the greater your chance of developing coronary heart disease. Also, the greater the level of each risk factor, the greater the risk. For example, a person with a total cholesterol of 300 mg/dL has a greater risk than someone with a total cholesterol of 245 mg/dL, even though everyone with a total cholesterol greater than 240 is considered high-risk. 

What are the major risk factors that can't be changed?

Increasing age: About 82 percent of people who die of coronary heart disease are 65 or older. At older ages, women who have heart attacks are more likely than men are to die from them within a few weeks. 

Male sex (gender): Men have a greater risk of heart attack than women do, and they have attacks earlier in life. Even after menopause, when women's death rate from heart disease increases, it's not as great as men's. 

Heredity (including Race): Children of parents with heart disease are more likely to develop it themselves. African Americans have more severe high blood pressure than Caucasians and a higher risk of heart disease. Heart disease risk is also higher among Mexican Americans, American Indians, native Hawaiians and some Asian Americans. This is partly due to higher rates of obesity and diabetes. Most people with a strong family history of heart disease have one or more other risk factors. Just as you can't control your age, sex and race, you can't control your family history. Therefore, it's even more important to treat and control any other risk factors you have. 

Major risk factors you can modify, treat or control by changing your lifestyle or taking medicine

Tobacco smoke: Smokers' risk of developing coronary heart disease is 2–4 times that of nonsmokers. Cigarette smoking is a powerful independent risk factor for sudden cardiac death in patients with coronary heart disease; smokers have about twice the risk of nonsmokers. Cigarette smoking also acts with other risk factors to greatly increase the risk for coronary heart disease. People who smoke cigars or pipes seem to have a higher risk of death from coronary heart disease (and possibly stroke) but their risk isn't as great as cigarette smokers'. Exposure to other people's smoke increases the risk of heart disease even for nonsmokers. 

High blood cholesterol: As blood cholesterol rises, so does risk of coronary heart disease. When other risk factors (such as high blood pressure and tobacco smoke) are present, this risk increases even more. A person's cholesterol level is also affected by age, sex, heredity and diet. Here’s the lowdown on where those numbers need to be:

Total Cholesterol: Less than 200 mg/dL
 
LDL (bad) Cholesterol:

• If you're at low risk for heart disease: Less than 160 mg/dL
• If you're at intermediate risk for heart disease: Less than 130 mg/dL
• If you're at high risk for heart disease (including those with existing heart disease or diabetes): Less than 100mg/dL

HDL (good) Cholesterol: 40 mg/dL or higher for men and 50 mg/dL or higher for women
 
Triglycerides: Less than 150 mg/dL 

High blood pressure: High blood pressure increases the heart's workload, causing the heart to thicken and become stiffer. This stiffening of the heart muscle is not normal, and causes the heart not to work properly.  It also increases your risk of stroke, heart attack, kidney failure and congestive heart failure. When high blood pressure exists with obesity, smoking, high blood cholesterol levels or diabetes, the risk of heart attack or stroke increases several times. 

Physical inactivity: An inactive lifestyle is a risk factor for coronary heart disease. Regular, moderate-to-vigorous physical activity helps prevent heart and blood vessel disease. The more vigorous the activity, the greater your benefits. However, even moderate-intensity activities help if done regularly and long term. Physical activity can help control blood cholesterol, diabetes and obesity, as well as help lower blood pressure in some people. 

Obesity and overweight: People who have excess body fat — especially if a lot of it is at the waist — are more likely to develop heart disease and stroke even if they have no other risk factors. Excess weight increases the heart's work. It also raises blood pressure and blood cholesterol and triglyceride levels, and lowers HDL ("good") cholesterol levels. It can also make diabetes more likely to develop. Many obese and overweight people may have difficulty losing weight. But by losing even as few as 10 pounds, you can lower your heart disease risk. 

Diabetes mellitus : Diabetes seriously increases your risk of developing cardiovascular disease. Even when glucose levels are under control, diabetes increases the risk of heart disease and stroke, but the risks are even greater if blood sugar is not well controlled. At least 65% of people with diabetes die of some form of heart or blood vessel disease. If you have diabetes, it's extremely important to work with your healthcare provider to manage it and control any other risk factors you can. Persons who are obese or overweight should lose weight to keep blood sugar in control.    

What other factors contribute to heart disease risk?

Stress: Individual response to stress may be a contributing factor. Some scientists have noted a relationship between coronary heart disease risk and stress in a person's life, their health behaviors and socioeconomic status. These factors may affect established risk factors. For example, people under stress may overeat, start smoking or smoke more than they otherwise would.

Alcohol: Drinking too much alcohol can raise blood pressure, cause heart failure and lead to stroke. It can contribute to high triglycerides, cancer and other diseases, and produce irregular heartbeats. It contributes to obesity, alcoholism, suicide and accidents. The risk of heart disease in people who drink moderate amounts of alcohol (an average of one drink for women or two drinks for men per day) is lower than in nondrinkers. One drink is defined as 1-1/2 fluid ounces (fl oz) of 80-proof spirits (such as bourbon, Scotch, vodka, gin, etc.), 1 fl oz of 100-proof spirits, 4 fl oz of wine or 12 fl oz of beer. It's not recommended that nondrinkers start using alcohol or that drinkers increase the amount they drink. 

Diet and Nutrition:  A healthy diet is one of the best weapons you have to fight cardiovascular disease. The food you eat (and the amount) can affect other controllable risk factors: cholesterol, blood pressure, diabetes and overweight. Choose nutrient-rich foods — which have vitamins, minerals, fiber and other nutrients but are lower in calories — over nutrient-poor foods. A diet rich in vegetables, fruits, whole-grain and high-fiber foods, fish, lean protein and fat-free or low-fat dairy products is the key. And to maintain a healthy weight, coordinate your diet with your physical activity level so you're using up as many calories as you take in.

Source: American Heart Association. www.americanheart.org