| | Permit me to offer a dissenting voice here. I have been on the Pritikin diet for the last 20 years, and it has lowered my blood pressure and reduced my cholesterol dramatically. Prior to going on the diet, my total cholesterol was 185. In a little over a month, it had dropped to 115. It has since gone up some, but still remains around 150. My blood pressure was 134/90 before starting the diet. In two years, it had dropped to 100/70. Right now, it averages around 110/65. I currently weigh less than I have at any time in my adult life. My doctor says that I'm in excellent health.
Nathan Pritikin, founder of the diet, had severe heart disease before he developed it, as well as a serious form of leukemia. In two years, his cardiovascular health had improved so much that his doctor, who had said that his heart disease was incurable, was stunned, and could offer no explanation. This was before the effects of serum cholesterol on cardiovascular disease were well known. Pritikin was largely responsible for making that information available to the general public and to the medical profession as well. His leukemia also went into remission shortly after he had been on the diet, and it stayed in remission for the next 25 years until he had a relapse at around the age of 70, due to a decline in immune function secondary to aging. We know now that an extremely low fat, low sugar diet can prevent cancer and in some cases reverse it, just as it can for atherosclerosis.
The Women's Health Initiative trial did not prove much of anything when it concluded that a low-fat diet doesn't reduce heart disease. The diet simply wasn't low enough in fat. This allegedly "low-fat" regimen was 29% of total calories as fat, which is far too high an amount for producing any measurable change in cardiovascular risk factors. Dean Ornish pointed this out in his criticism of the study. To get any measurable effect, you have to drop the fat content down to 10% of total calories. This has been known for some time, which means that the people conducting the study were ill informed and irresponsible in the way they designed and controlled it.
Also, Anthony's Colpo's observation that among the 3.4 percent of trial participants with pre-existing cardiovascular disease, those randomized to the low-fat diet experienced a 26% increase in the relative risk of non-fatal and fatal CHD doesn't prove much of anything, because these individuals could have had a defect in their cholesterol metabolism to begin with, which would have caused their risk factors to increase regardless of any change in diet. 3.4% is such a small portion of the trial participants as to be statistically insignificant. It is reasonable to conclude that it wasn't the low-fat diet that caused them to get worse, but that they got worse in spite of it. This happens with a very small percentage of the population that is born with very few cholesterol receptors in their livers, so that diet doesn't help them. Drugs are required, and even they are often ineffective. But these are genetic abnormalities; they are not typical of the general population.
Colpo also mentions another study in which women were given diets with different levels of saturated fat, and the ones given less saturated fat had a greater narrowing of the coronary arteries. There was no mention of whether or not total fat was reduced, and it probably was not, because the study apparently examined only the effects of saturated fat, so it would presumably have kept the total fat intake the same, in order not to confuse the results with a reduction in total fat. Yet, Colpo writes as if total fat were decreased, which is misleading, if the reduction in saturated fat was compensated for by an increase in polyunsaturated fat. It would make sense that an increase in polyunsaturated fat in place of saturated fat might be expected to increase atherosclerosis, given the greater tendency for oxidation of existing serum cholesterol from the polyunsaturated oils. Pritikin recommends keeping all fats low, including polyunsaturated fat. He also recommends keeping simple sugars low, which can raise triglycerides and increase atherosclerotic progression in susceptible individuals -- those who are hyperglycemic and hyperinsulinemic.
Colpo's own case is interesting. I'm not sure what to make of it, but it is contrary to all the research currently available on the effects of a very low-fat diet, which are positive in the vast majority of the people who try it and manage to stay on it. His experience must be kept in perspective as strictly anecdotal, although it is certainly something that should be looked into. I would want to know if he was doing anything else, like drinking alcohol, that he neglected to mention. Anecdotal cases are problematic for precisely this reason; they do not constitute large, well-controlled studies. Someone's personal report on what he did is notoriously unreliable, which is why double-blind studies are considered so important.
Personally, I think that Anthony Colpo is serving up a high-fat stew of half-truths, dietary polemics and misleading generalizations. I can cite references from the American Journal of Clinical Nutrition that contradict his assertions, especially his claim that without dietary fat, carotenes cannot be properly absorbed. Also, his claim that athletes only do well on the Pritikin diet during three or four days of a carbo-loading phase is contradicted by the evidence. Many top athletes have been on the Pritikin diet for years, and it shows dramatically in their superior performances.
The Hawaii Ironman Triathlon is a grueling annual event consisting of a 2.4-mile ocean swim, 112-mile bicycle race, and a 26.2-mile marathon run. For six weeks prior to the 1982 Ironman, Dave Scott, Scott Tinley, and Scott Molina were monitored as they trained on the Pritikin diet. In Hawaii, a special Pritikin kitchen was set up for their meals. On the day of the '82 Hawaii Triathlon, the heat was almost unbearable and the black asphalt road reached temperatures up to 115 degrees F. These three runners finished 1st, 2nd and 4th place. Dave Scott, the winner, won in a record time that was 16 minutes faster than his previous best. As it turned out, he had been following his own version of the Pritikin diet for several years and preparing his own food. One of the reasons that these athletes did so well on that diet is not only the extra glycogen from their high carb diets, but also the very low fat content of the diet, which improves circulation dramatically, as fat causes the red corpuscles and other blood cells to stick together, impairing oxygen delivery to the muscles. One runner I recommended the diet to told me how much easier it was for him to breath when he was on it.
There are many other examples of world-class athletes who owe their success to the Pritikin diet. I won't bother to list them all, but Rob de Castella is another one, who won the 1983 Rotterdam, Holland marathon in 2:08:18 (a spectacular time) and attributes his success to the Pritikin diet.
The epidemiologic evidence contradicts Colpo as well. Primitive people like the Tarahumara Indians of the Creel area of Chihuahua, Mexico follow a diet that is between 9 and 12% of total calories as fat. Their diet consists largely of corn, pinto beans, and other plant foods. They exceed the Food and Agriculture Organization/World Health Organization recommendations for vitamin A by 2 1/2 times, and only 3% of the vitamin A in their diet comes from animal products. Corn provides 56% of the vitamin A intake, and 35% comes from greens. Their adult cholesterol levels range between 100 and 140 mg/dL, and there isn't a documented case of heart disease among the entire population.
The natives of Papua, New Guinea follow a diet that has only 3% of total calories as fat, and consume only 0.7% of total calories as essential fatty acids, yet they exhibit no evidence of an essential fatty acid deficiency, which includes scaly skin, unusual pigmentation, and inability of the skin to heal. Hair loss, one of the first symptoms of an EFA deficiency, was not observed. It is believed that the ratio of linoleic acid to linolenic acid is more important than the absolute amounts. Needless to say, there is no heart disease among the New Guineans.
African tribes who are predominantly vegetarian and follow a very low-fat diet are another example. They have average serum cholesterols of 110 mg/dL and no heart disease. Wherever you look in a study of populations, those that are on something like the Pritikin diet are completely free of heart disease.
It is true that a very low-fat diet reduces testosterone; it reduces estrogen as well. All hormones are lower on the Pritikin diet, and accordingly, hormone dependent cancers, like breast and prostate. Is that such a bad thing? Colpo writes as if the more testosterone, the better.
There's a lot of angry polemics and considerable hyperbole in his article, which should lead one to be a bit skeptical of his objectivity. He is clearly rebelling against a diet that he feels did him wrong, and looking for as much intellectual ammunition to discredit it as he can. In the process, however, he ignores vast amounts of evidence, both clinical and epidemiological, that high-fat, high-cholesterol diets are atherogenic and mutagenic. If he is going to convince the medical profession that a high intake of dietary fat is nothing to worry about, he has his work cut out for him.
Also, the idea that early man followed a certain diet does not automatically mean that that diet is necessarily ideal or one that will promote optimum health. Early man had only to live long enough to reproduce and in many cases didn't live much beyond that, given the hostile conditions that he had to deal with. We have absolutely no evidence that the diet he followed would enable us to live to a ripe old age by modern standards, since our early ancestors didn't come close to living that long. In fact, much of the current evidence indicates that longevity is increased by a low-calorie diet. Gerontologist Roy Walford, who did a lot of research on the effects of diet on maximum lifespan, said that something like the Pritikin diet has been shown to enhance longevity in all animals so far studied, including primates. There is no reason to believe that human beings are any different in this respect.
Anyway, as you can see, I'm not impressed by Colpo's acerbic criticism or by his objectivity.
- Bill
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