Understanding Ornish--When saturated fats cause heart disease
A lot of LCers cry "conspiracy" (me included) but I'm coming from a different direction. I think there was a "mistake" made with the Food Pyramid and with the government and the food industry cashed in on it. On the other hand, I understand where Ornish is coming from. For one, he doesn't understand ketosis.
But is his motivation bad? I don't think so. For one, there are actually several studies showing that eating a low-fat diet lowers total cholesterol (if you had been eating a lot of saturated fat, trans fat and a high carb loaded added to it.) Ornish and others are going by this factor. They are coming from a different perspective and there is science behind it.
Three studies showed that reductions in saturated fat and cholesterol intakes are associated with a decreased incidence in atherosclerotic cardiovascular disease. And you'll notice that Ornish was in on one of them (see below 1, 2, 3).
Okay, so this makes Ornish and others enthusiastic about lowing intake of saturated fats and going on a low-fat diet. But what is wrong with this thinking? Well, it has also been abundantly proven that low-fat diets reduce HDL which makes people perhaps more at risk for coronory heart disease than any other factor (see below 4). I quote from this study: "It has been well established that the higher the HDL-cholesterol concentration, the lower the risk of atherogenesis, and, in epidemiologic studies, low HDL-cholesterol concentrations are a risk factor for coronary heart disease... It is well established that the composition of the diet affects HDL-cholesterol concentrations, with an increase during higher intakes of saturated fat and a decrease when saturated fat is replaced with unsaturated fat or carbohydrates." So the problem now becomes for these scientists who don't recognize low-carbing as an option: Is it more important to decrease cholesterol or more important to increase HDL?
You can see how confused they are. They ignore the fact that low-carbing gives you the benefit of saturated fat raises in HDL while not causing the same rise in total cholesterol, LDL, and triglycerides because of not consuming enough glucose/insulin raising calories to affect these.
That is why one study says that perhaps low-fat diets (which produce "adverse metabolic changes" should only be suggested to those at high risk for heart disease while people with normal cholesterol levels should eat "normal" amounts of fat. I quote from article 5. below: It is not known which of the various lipoprotein indexes used in these studies provides the best prediction of risk of developing coronary artery disease, but overall the results suggest that high-risk individuals, such as those with elevated LDL-cholesterol concentrations or small, dense LDL particles, or both, may be the most appropriate candidates for diets low in total fat (eg, providing much less than 30% of energy), whereas the apparently adverse metabolic changes with such diets may be of particular concern to those individuals who have lipoprotein profiles indicating a low risk of CHD while consuming their usual diets."
That is why the American Heart Association itself said about the same thing (see 6. below): "Dr Ronald Krauss, chairman of the association's nutrition committee, said that studies in healthy people show that there are genetic differences in the response to a low fat diet. Those who, from their metabolic profiles, are at highest risk of heart disease show the greatest benefit from very low fat diets, but the remaining two thirds of the population would show only minimal benefit, and for some it would be harmful."
Ornish has made up his mind that it is better to risk lower HDL than to risk higher cholesterol. He has not considered the fact that cutting out carbs could lower cholesterol because frankly there hasn't been many grants to fund such studies and the ones that do show an improvement in cholesterol through lowering carbs come to very timid conclusions about it.
Only time and articles like Gary Taubes in the NY Times and current ongoing studies in low-carb will put an end to the issue.
1. Hjermann I, Holme I, Velve Byre K, Leren P. Effect of diet and smoking intervention on the incidence of coronary heart disease: report from the Oslo Study Group of a randomized trial in healthy men. Lancet 1981;2:1303–10.[Medline]
2. Ornish D, Brown SE, Scherwitz LW, et al. Can lifestyle changes reverse coronary heart disease? The Lifestyle Heart Trial. Lancet 1990;336:129–33.[Medline]
3. Watts GF, Lewis B, Brunt JNH, et al. Effects on coronary artery disease of lipid-lowering diet, or diet plus cholestyramine, in the St. Thomas' Atherosclerosis Regression Study (STARS). Lancet 1992;339:563–9.[Medline]
4. American Journal of Clinical Nutrition, Vol. 70, No. 6, 992-1000, December 1999 HDL-subpopulation patterns in response to reductions in dietary total and saturated fat intakes in healthy subjects
5.American Journal of Clinical Nutrition, Vol. 70, No. 6, 949-950, December 1999 Low-fat diets, lipoprotein subclasses, and heart disease risk Paul T Williams and Ronald M Krauss
6. BMJ 1998;316:571 ( 21 February ) Very low fat diets may harm some people