The Cholesterol Controversy – Food for Thought

The Inarguable Truth About the Diet/Heart Theory

Jun 18, 2009

The more cholesterol or saturated fat one consumes, the greater is the risk of suffering from heart attacks and strokes. But is it really the case?

If a person consumes more cholesterol or saturated fat, his blood cholesterol levels will rise to dangerous levels. This excess cholesterol will then produce thick plaques in his arteries which will eventually obstruct the flow of blood leading to coronary heart disease (CHD) or strokes…So, what’s new in this? We all know about it. We know it as the LDL hypothesis. Some call it the Diet/Heart hypothesis. It is a fact. Or is it?

For years we have been led to believe that this is the truth and that cholesterol is bad. It all started in the 1850s from the early observations of people like Rudolph Virchow, a study by Ashoff in the early 1900s and finally Ancel Key's seminal Seven Countries Study, demonstrating clear links between saturated fat intake and heart disease in 1954. This led to the development of a multi-billion dollar industry catering to the consumer’s growing consciousness of fat/cholesterol free foods and dietary supplements that help reduce cholesterol in the blood. In the 1980s, statins were launched. These drugs protected people from CHD by lowering the blood cholesterol. So far so good. But what is this cholesterol, by the way?

Wikipedia describes cholesterol as a lipidic, waxy steroid found in the cell membranes and transported in the blood plasma of all animals. It is an essential component of mammalian cell membranes where it is required to establish proper membrane permeability and fluidity. Cholesterol is an important precursor molecule for the synthesis of Vitamin D and the steroid hormones like cortisol, aldosterone, progesterone, estrogens and testesterone. In short, cholesterol is a life-essential substance. So when does it turn into a villain? It does not. The culprit in question is called LDL or Low Density Lipoprotein.

Since cholesterol is insoluble in the body, the task of carrying it in blood circulation is done by substances called lipoproteins like chylomicrons. After cholesterol is absorbed by the intestinal wall, it is rammed inside a chylomicron which takes it to the liver. In the liver, the chylomicrons are absorbed, broken down, and reconstructed into a smaller type of lipoprotein known as a Very Low Density Lipoprotein VLDL. These VLDLs then go out into the general circulation and eventually get converted to LDLs.

Current thinking in CHD is that when the level of LDL is raised, they travel through the artery wall and form a big lumpy cholesterol deposit (plaques) that narrows the artery. Cholesterol is found in plaques because LDL contains lots of cholesterol. This plaque may get bigger and finally obstruct blood flow to the extent that the person may suffer from a heart attack. Or if the plaque bursts, it may cause the formation of a blood clot over the ruptured area.

But raised LDL levels have nothing to do with increased chances of getting CHD. Even people with low LDL levels suffer from CHD. Furthermore, LDL levels and cholesterol levels in your blood have nothing to do with a person’s saturated fat or cholesterol intake. Fats, saturated or otherwise, are chemically different from cholesterol or LDL and thus how much fat one eats has nothing to do with the one’s LDL or cholesterol levels. Surprised? Don’t be, because the father of the diet/heart hypothesis, Ancel Keys, himself has quoted in a paper in 1956 that, ‘In the adult man the serum cholesterol level is essentially independent of the cholesterol intake over the whole range of human diets.’

Two major long term studies on this phenomenon, Framingham and Tecumseh have clearly established that dietary intake of cholesterol has no impact on the level of cholesterol in one’s blood. Similarly the studies also found out that the intake of saturated fats also had no effect on one’s blood cholesterol levels. In fact, William Castelli, director of the Framingham study for many years, stated that the people who ate the most cholesterol, ate the most saturated fat, ate the most calories weighed the least and were the most physically active.

The beginning of the end?

Studies in many countries have corroborated the fact that raised LDL levels do not mean an increased incidence of CHD. In fact, in many studies it was shown that as the LDL/cholesterol levels went up, CHD went down. These studies have been published in prestigious journals like Lancet, JAMA and Atherosclerosis.

The celebrated chemist Joseph Black warned over 200 years ago: ‘A nice adaptation of conditions will make almost any hypothesis agree with the phenomena. This will please the imagination, but does not advance our knowledge.’ Contradictions to the cholesterol hypothesis have been appearing time and again but it has become too important an issue to let go. The statin industry itself is worth more than 30 billion dollars not to mention the low fat/zero cholesterol food and supplements and antioxidants industry.

As Dr. Malcolm Kendrick of The International Network of Cholesterol Skeptics (THINCS; www.thincs.org) says, “Time, I think, that it (the theory) was consigned to the dustbin of history. It is not simple, direct, or understandable - the only certain thing about it is that it is wrong.”

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