Sunday, July 8, 2012

A Registered Dietitician's Letter to the ADA

After all this research, I have come to the conclusion that both proponents and adversaries of the lipid hypothesis have blind spots. Proponents have recognized the role oxidized LDL plays in atherogenesis and the role the LDL receptor gene plays in getting cholesterol into the cells, but still insist that we should control cholesterol production to reduce the amount in the blood. They still insist on lowering LDL even though studies show it is not the amount of LDL but the amount of oxidized LDL that is the problem. They insist on a low saturated fat and cholesterol diet even though they admit that diet does not play a role in the lipid hypothesis. Adversaries of the lipid hypothesis insist that cholesterol does not play a role in heart disease, despite evidence that oxidized LDL promotes atherosclerosis.
It appears to me that we may be doing more harm than good in recommending a diet high in vegetable oils and low in saturated fat and cholesterol. After all, we developed heart disease, cancer, diabetes and obesity while decreasing saturated fat intake and increasing vegetable oil intake. It seems ridiculous to blame a fat that has been around for thousands of years for diseases that have only been around for the past 100 years. Vegetable oils have also only been used in the past 100 years. The currently accepted low-fat, food-guide-pyramid diet may be causing the very disease we are prescribing the diet to prevent. Based on the evidence, I cannot with a clear conscious recommend a diet high in vegetable oils and low in saturated fat. There is just no good science to support that recommendation and a good deal of science that would contradict that recommendation. I believe it is more important to be scientifically correct than politically correct. And politics has played a more significant role than science in our dietary recommendations whether we choose to believe that or not.
Dietitians are promoted as “the nutrition expert.” How can we possibly make that claim if we do not abide by what the science actually says? How can we claim to be science-based when we ignore every piece of science that contradicts the view we want to take? Our view should be based on the actual science, not the politics behind the science. The science that has come out in the last twenty to thirty years clearly contradicts the diet-heart hypothesis and the lipid hypothesis in its present form. So, trying to lower total cholesterol and LDL cholesterol is a waste of time because it does nothing to prevent LDL from becoming oxidized and, therefore, is not helpful in preventing atherosclerosis.

Based on all the evidence so far, I believe the following:

  1. There is no scientific support for the diet-heart hypothesis, the belief that saturated fat and cholesterol in the diet cause atherosclerosis and heart disease.
  2. The lipid hypothesis is not true in its present form. It is not the amount of cholesterol in the blood that matters, but the amount of oxidized LDL, so I would support the oxidized lipid hypothesis.
  3. I support diet recommendations that prevent the oxidation of LDL.
    1. Reduction of PUFA intake
    2. Increase in cholesterol and saturated fat intake
    3. Increase in antioxidant intake
  4. I support looking into ways to increase LDL receptor function. A recent study shows that curcurmin may be beneficial here (97) and thyroid hormone and iodine may play a role as well.

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