An Example of Junk Science
By Mary Enig, PhD
While the establishment is finally recognizing the dangers of trans fatty acids, conventional dietary gurus continue to warn the public about the alleged dangers of saturated fats. In this article, we will look at a study published in 1997 in the American Journal of Cardiology (79:350-354) used to justify avoidance of red meat and butterfat, the two main sources of saturated fatty acids in the Western diet.
Arthur Agatston, author of the best-selling South Beach Diet refers to this research when he states: “The major problem I have with the Atkins Diet is the liberal intake of saturated fats. There is evidence now that immediately following a meal of saturated fats, there is dysfunction in the arteries, including those that supply the heart muscle with blood. As a result, the lining of the arteries (the endothelium) is predisposed to constriction and clotting. Imagine: Under the right (or rather, wrong) circumstances, eating a meal that’s high in saturated fat can trigger a heart attack! In addition, after a high-fat meal certain elements in the blood called remnant particles, persist for longer than is healthy. These particles contribute to the buildup of plaque in the vessel wall.” Agatston recommends consuming polyunsaturated and monounsaturated vegetable oils, including tub spreads, rather than animal fats like butter.
In the study, carried out by Robert A. Vogel and his team at the University of Maryland School of Medicine, ten volunteers were tested for “endothelial function” by measuring the diameter change in the brachial artery using ultrasound after a high-fat and a lowfat meal, each of 900 calories. (The endothelium is the lining of the arteries.) The high-fat meal contained 50 grams of fat and the lowfat meal contained–according to the authors–0 grams of fat. (Actually, no food is completely devoid of fat, even skim milk.)
“Flow-mediated vascularity” did decrease more in the high-fat group compared to the lowfat group. Interestingly, LDL-cholesterol declined slightly for both groups but in the lowfat
group, the so-called good HDL-cholesterol also declined, whereas it remained stable in the high-fat group. Blood pressure declined in the high-fat group, but rose in the lowfat group. Most significantly, blood glucose rose in the lowfat group, but declined slightly and then returned to baseline in the high-fat group.
For years we have been hearing that high-fat foods raise so-called bad LDL-cholesterol and blood pressure and therefore contribute to heart disease. But since that didn’t happen in this study, the authors have declared that an inherently subjective measurement of “endothelial function” is a better marker for heart disease.
But was it saturated fat that caused the decline in endothelial function? The high-fat meal consisted of an egg McMuffin, sausage McMuffin, two hash brown patties and a noncaffeinated beverage. The lowfat meal consisted of Frosted Flakes, skimmed milk and orange juice. According to the authors, the high fat meal contained 50 grams of fat, of which 14 were saturated fat. So only 28 percent of the fat in the high-fat meal was saturated. The rest was a combination of trans fats, monounsaturated and polyunsaturated fat, any one of which, or all together are the likely culprits in the decline in endothelial function. But Agatston (along with the study authors) blames the adverse effects on saturated fats!
The lowfat meal that won the endothelial-function contest is obviously a terrible meal–extremely high in sugar and devoid of nutrients. Yet it does have one thing going for it–it is unlikely that Frosted Flakes, skim milk or orange juice contain MSG, whereas the high-fat meal certainly contained MSG in the sausage and hash browns. If the bread contained soy, which it probably did, this would be another source of MSG. The presence of MSG in the high-fat meal provides a likely explanation for the decline in endothelial function.
The subjects in this study ate junk food and the research itself can only be described as junk. The study was designed so poorly that no conclusions can be drawn from it. In order to test the effects of saturated fat on endothelial function, the researchers should have provided two identical meals of simple whole foods, except for the addition of a mostly saturated fat such as suet or coconut oil to one of the meals. Then, to compare the effects of the various fats with saturated fat, the researchers should have repeated the experiment adding a mostly monounsaturated fat, such as olive oil, to one of the meals, a high-trans fat such as vegetable shortening and finally a polyunsaturated fat such as corn oil.
To correlate their findings–temporary decline in endothelial function–with long-term effects such as heart disease, the authors should have been able to cite numerous studies; but they cite only one, which postulates a chronic decline in endothelial function with atherosclerosis. They provide no evidence that the temporary decline in endothelial function observed in this study is associated with atherosclerosis in the long term or can “trigger a heart attack.”
As it becomes more and more obvious that cholesterol levels have little predictive value for heart disease–and that saturated fats in fact have little or no effect on cholesterol levels anyway–researchers are searching for other ways to demonize saturated fats. The study carried out by Vogel and his team can only be characterized as “garbage in, garbage out,” a “grasping-at-straws” attempt to stem the change in consumer eating habits towards real, whole foods.