Cholesterol, diet & heart disease

Townsend Letter for Doctors and Patients,  May, 2005  by Jule Klotter

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In their article "The Role of Cholesterol and Diet in Heart Disease," public health scientists Alice Ottoboni, PhD, and Fred Ottoboni, MPH, PhD, explain the fallacies that underlie the hypothesis that cholesterol and high-fat diets cause heart disease. Although cholesterol (particularly LDL-cholesterol) has been maligned, it performs several necessary functions in the body. Cholesterol, a sterol (steroid alcohol) found only in animal tissue, provides membrane flexibility for every cell in the body. Without cholesterol, our bodies could not make steroid or sex hormones, vitamin D, bile acids, or other necessary biochemicals. Cholesterol combined with the proteins that transport it form LDL and HDL (low-density and high-density lipoproteins). HDL cholesterol is being carried back to the liver and gallbladder for excretion. LDL cholesterol is moving to parts of the body that need it. The Ottobonis say, "Because one of these needs is to deposit cholesterol over inflamed arterial lesions, LDL has been labeled 'bad.' This designation is unfortunate because the deposition is a mechanism to protect against further damage, rather than a cause of damage."

Nearly every cell in the body produces some cholesterol, but the bulk of it is made by the liver. In a healthy person, the body produces cholesterol according to its needs and the amount of cholesterol eaten. When cholesterol-rich foods are consumed, the body makes less cholesterol; and when less cholesterol is eaten, the body makes more of it, keeping cholesterol levels fairly constant. A diet that restricts cholesterol-containing foods has little effect on blood cholesterol levels. But that is beside the point. After researching the scientific literature, the Ottobonis concluded that "high blood cholesterol and heart attacks do not have a causal relationship, but rather are co-symptoms of an unhealthful dietary regime."

How did cholesterol become the "fall guy" for heart disease? The cholesterol hypothesis stems from the Framingham Heart Study, initiated in 1948, and the research of nutritionist Ancel Keys and his wife Margaret. The Framingham Study, which looked at the diet, lifestyles, and environments of a large number of families, found a correlation between high cholesterol levels and heart attacks. About the same time, the Keys began looking for a correlation between diet and heart disease. They believed that the low-animal-fat diet, which they identified as the Mediterranean diet, protected against coronary heart disease and that diets high in animal fat promoted heart disease. The Keys collected statistics on deaths from coronary heart disease and fat consumption. Although over 20 countries had such statistics at the time, Ancel Keys used data from just the six countries that supported the animal fat (cholesterol)--heart disease hypothesis. Drawing on the Framingham study and Keys' report, representatives of the American Heart Association (AHA) told a TV audience in 1956, that "the cause of coronary heart disease was butter, lard, beef, and eggs." The US government soon began recommending the AHA low-fat, high-carbohydrate diet that promotes the use of vegetable seed oils, margarine, chicken, bread, and cereals.

Although other nutrition studies since that time have reported a correlation between a high-fat diet and heart disease, the Ottobonis criticize many of these studies for focusing solely on fat consumption and ignoring other dietary factors, such as sugar. The few studies that included sugar consumption in the data found that people whose diets were high in fat also ate high quantities of sugar. These researchers proposed that sugar, not dietary cholesterol, is the real culprit in heart disease. As the Ottobonis explain in their article, sugar's contribution to coronary heart disease is supported by biochemical facts. When a diet is high in sugar and starches (both of which break down and produce glucose), the resulting increase in blood glucose levels triggers the pancreas to produce more insulin. Insulin helps turn excess glucose into body fat and cholesterol. Because of this sugar-insulin-fat connection, long-term consumption of sugars and starches promote high cholesterol levels, obesity, insulin resistance, chronic inflammation, and other risk factors associated with heart disease. Diet also affects homocysteine levels, another recognized marker for heart disease. Too much homocysteine damages arterial walls, promoting the formation of plaque and blood clots. High levels of homocysteine can result from deficiencies of vitamin B6, B12, and folic acid.

In their excellent book The Modern Nutritional Diseases: Heart Disease, Stroke, Type-2 Diabetes, Obesity, Cancer, and How to Prevent Them, the Ottobonis describe in detail how our abundance of sugar, starch, and hydrogenated fats and lack of essential fatty acids have promoted heart diseases and other degenerative illnesses. The Ottobonis urge readers to take personal responsibility for their health and to remember that "the human body is a very forgiving creature and will respond favorably to good nutrition, even after decades of abuse. And to keep in mind ... there are no drugs that can cure a nutritional disease!"