Does being a vegan mean you won’t get heart disease?

Heart artery plaque- low fat diet doesn’t prevent this

In 1998 Dean Ornish published his data showing a 3 percent reduction in the plaques seen by coronary angiograms on a select group of patients who followed his diet and “lifestyle” plan.  To be exact: they found 1.75% improvement after one year and 3.1% improvement after five years.  Where the control group increased by 2.3% in one year and 11.8% at five years. This was a group of 28 patients who followed his diet to the letter.

Today people are touting the cardiologist, Dr. Kim Williams, president-elect of the American College of Cardiology,  who became a vegan and watched some of his lipid levels improve. What we do not know about his lipid levels were the other foods he ate, what other changes he might be taking – but the news is that veganism is good for the heart. But is it? The Ornish diet restricts not only meat, but refined carbohydrates like added sugars and white flour, which have been implicated in cardiovascular disease.

Since the paper was published in 1998 no one has reproduced that data. No one. In medicine we see a lot of data come through, when it is not reproduced, or unable to be reproduced by others we look at it with a very jaundiced eye. Or to be blunt – we don’t believe it. Yet, his data, with all the issues it has- is still touted by a few in the popular press as “proof” that the “low fat” works. We have levels of evidence in medicine, and while Ornish attempted to get to the highest level of evidence, by having a control group – he fell short with several major statistical issues: (a) his study does not contain enough people to be anywhere nearly significant (b) one cannot rely on angiographic photographs which are interpreted in many different manners (c) one cannot control outside factors, exercise, BMI, smoking cessation.

In contrast, we now have an entire group of lipid medications. A recent study in New England Journal of Medicine showed how that Crestor had produced a regression of plaque in 63% of the individuals. Reproduced. Although most would say they would rather eat vegetables than take a medicine- and I would agree, except that the reduction in plaque from Dr. Ornish studies is not even close to what medications can do.

Modern methods (since Ornish paper in 1998) of measuring arterial plaque are far more sensitive. Intra-vascular ultrasound where they thread a tiny ultrasound probe into the artery and  measure the plaque precisely.   In the Ornish data, he used photos of angiograms ( show two cardiologist the same angiograms and you will get two different interpretations of it – angiograms are not precise). The medications show specific reductions in plaque- not everyones – unlike Ornish. It is rare that anything does 100 per cent to everyone.

When looking at angiograms- like Ornish did- the interpretation of them is so variable, that no scientific publication today would accept that data, or its interpretation. The small amount of plaque reduction is too small to be anything but observer bias.

Two views of the same image- angiogram interpretation is flawed

From one old paper- Dean Ornish has made a career, being the anti-Atkins, and riding the anti-cholesterol, low-fat band wagon with the same religious fervor as Keyes did thirty years ago (see my earlier post about that). His data is quoted by other vegans, as gospel about how heart disease can change – and yet what is missing: no one has done it again.

The difficulty is this: science has caught up with us, and we know a lot more about how plaque forms and doesn’t form. We know that dietary cholesterol is far less important that what the liver makes. We know that the dietary component may be far more related to the triglycerides – and they are raised far more by the grains and pastas that Ornish loves.

Ornish is the lead health-blogger for Huffington Post, has influenced Bill Clinton (see the previous post) and is favorably mentioned by Dr. Oz. He still argues against those who advocate any “low carbohydrate” solution, based on his “empiric” data.

Personality, the willingness to believe in  your hypothesis no matter what science says, and the desire by the public to see “natural” leads to a great career in politics, and entertainment. For most scientists, Ornish’s paper isn’t a breakthrough, but borders on confabulation.