I became a bit puzzled the other day when I read a blog article written by Kim A Williams MD, a cardiologist at Rush University in Chicago and the next president of the American College of Cardiology.
Doctor Williams describes how one of his patient’s history inspired him to change his dietary habits and adopt a cholesterol free, plant-based diet.
He finds it interesting that the American Heart Association prevention guidelines do not specifically recommend a vegan diet.
Dr. Williams writes: “…Wouldn’t it be a laudable goal of the American College of Cardiology to put ourselves out of business with a generation or two“…
Obviously, he’s implying that heart disease may be eliminated if we all go vegan.
To make my case clear I have to emphasize that my puzzlement has nothing to do with whether I believe Dr. Williams is right or wrong. In fact, he might very well be right. However, the question is whether his implications are supported by scientific evidence.
Should doctors base their treatment decisions on anecdotal evidence?
We often warn our patients to adopt the experience of other people and make it their own, both when it comes to interpreting symptoms and advising treatment strategies.
However, to be fair to Dr. Williams I will mention that he believes that studies on vegan diets are “either very large and observational or small and randomized“…
But, then he’s also implying that the scientific data isn’t strong enough to recommend heart patients or the general public to become vegetarians. So where is he going then?
Vegan Diets and Heart Disease
The health of vegetarians has been addressed in a number of studies. The health effects of foods that are preferred or avoided by vegetarians has also been studied. Most of these studies are of observational nature. Suffice to say that there is strong evidence that vegetarians have lower rates of coronary heart disease, lower LDL-cholesterol and lower rates of hypertension, diabetes and obesity.
A combined analysis of the five biggest cohorts published in 1999 showed a 24% lower mortality from coronary heart disease among vegetarians compared with non-vegetarians. Recently published data from the EPIC-Oxford Study showed that vegetarians had a 32% lower risk coronary heart disease than did non-vegetarians. Vegetarians had lower BMI, non-HDL cholesterol and blood pressure.
Randomized studies of vegetarian diets are few and small. Ornish’s Lifestyle Heart Trial showed a regression of coronary artery plaques among patients who adopted a program consisting of a low-fat vegetarian diet, stopping smoking, stress management and moderate exercise, compared with a “usual care” control group. These results were achieved without the use of cholesterol-lowering drugs. Although the study was randomized, only 48 individuals participated.
Another old and often cited study by Lester M. Morrison published 1960 tested 100 patients with proved coronary atherosclerosis. Fifty patients were treated with a low-fat, low-cholesterol diet. The other 50 patients were not given any specific treatment and acted as controls. By the end of 12 years, 19 of the 50 patients treated with the diet survived. Of the 50 control patients, all had died by the 12th year of observation.
Caldwin Esselstyn’s studies have also shown positive effects of a low-fat strategy in patients with coronary atherosclerosis. But again very few patients were studied. In his book, Prevent and Reverse Heart Disease, Esselstyn writes: … “I believe that coronary artery disease is preventable, and that even after it is under way, its progress can be stopped, its insidious effects reversed. I believe, and my work over the past twenty years has demonstrated, that all this can be accomplished without expensive mechanical intervention and with minimal use of drugs. The key lies in nutrition—specifically, in abandoning the toxic American diet and maintaining cholesterol levels well below those historically recommended by health policy experts…”
It’s the Cholesterol Stupid
Obviously, there is a lot of evidence suggesting that plant based diets positively affect atherosclerosis and coronary artery disease compared with a traditional Western dietary pattern. But many questions remain. Do we have to avoid all animal products? How about dairy foods, eggs and fish? What are the advantages and risks of soy consumption? What about compliance? Are vegetarian diets more difficult to stick with than other diets. Well, clearly more research is needed before we can answer the question whether cardiologists will be out of business if the world goes vegan.
Now let’s get back to Kim A Williams blog article. Williams apparently believes that cholesterol is what defines a healthy diet. He writes: … “I thought I had a healthy diet — no red meat, no fried foods, little dairy, just chicken breast and fish. But a simple Web search informed me that my chicken-breast meals had more cholesterol content (84 mg/100 g) than pork (62 mg/100 g). So I changed that day to a cholesterol-free diet, using “meat substitutes” commonly available in stores and restaurants for protein. Within 6 weeks my LDL cholesterol level was down to 90″...
In a paper published 2010 in the American Journal of Cardiology, William C. Roberts famously wrote: … “The lower the LDL cholesterol, the better, and this principle has been established repeatedly despite voices of the anticholesterol, antistatin fallacy mongers! It’s the cholesterol, stupid!“…
Dr. Roberts has been editor-in-chief of the American Journal of Cardiology for 32 years. Although not within the scope of my article, I can’t but wonder how many of the “anticholesterol, antistatin fallacy mongers” have managed to get their papers accepted for publication in the journal.
Mixing medicine with anal retentiveness is bad. You may remember that according to Freudian psychoanalysis “the term anal retentive (also anally retentive), commonly abbreviated to anal, is used to describe a person who pays such attention to detail that the obsession becomes an annoyance to others, potentially to the detriment of the anal-retentive person”.
So, let’s open our minds a little bit. Is it possible that the positive health effects of eating fruits and vegetables have to do with something else than cholesterol? I can assure you that by admitting that’s possible, you’re not saying that cholesterol doesn’t matter, and hopefully you’ll not be classified as an “anticholesterol fallacy monger.”
Last week The BMJ published a meta-analysis of sixteen cohort studies analysing the relation between fruit and vegetable consumption and risk of all cause, cardiovascular, and cancer mortality. Higher consumption of fruit and vegetables was significantly associated with a lower risk of all cause mortality. However, there was a threshold around five servings of fruit and vegetables a day, after which the risk of all cause mortality did not reduce further. Mortality from cardiovascular causes, but not cancer, was significantly related to less consumption of fruits and vegetables.
The authors discuss the possible mechanisms underlying their findings. Antioxidant compounds and polyphenols in fruit and vegetables—such as vitamin C, carotenoids, and flavonoids may play a role. These have been shown to prevent the oxidation of cholesterol and other lipids in the arteries and to increase the formation of prostacyclin with positive effects on arteries and blood clotting.
Reduction in blood pressure may play a role. Fruit and vegetables are good sources of magnesium and potassium, which have been inversely associated with mortality in previous studies. Fruit and vegetable increase plasma concentrations of antioxidants, such as alpha and beta carotene and other compounds such as vitamin C, carotenoids, and other phytochemicals may be important as well.
So, after all, it’s not only the cholesterol (stupid) …