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Earlier this week renowned podcaster Joe Rogan hosted a debate between vegan cardiologist Joel Kahn, MD and pro-paleo author Chris Kresser.
I have not yet heard this debate, BUT if the graphics below by Kresser are any evidence, more misinformation was shared to confuse people.
Cholesterol
Let’s start with the statement that there is no evidence that dietary cholesterol affects cholesterol. Wrong!
It is true that most of our cholesterol is synthesized, only about 20-30 percent comes from diet. Also true that there is down regulation in synthesis with increased consumption. So we absorb about 60 percent of consumed cholesterol BUT this number may be lower if you are a high consumer and higher if you are a low consumer, which is why vegans will see a dramatic rise in cholesterol if they start eating it.
That being said, ward studies show a very definitive increase in cholesterol with eating cholesterol. The prospective ward studies show an increase of 2-2.5 mg/dL per 100 mg of cholesterol.
Wrong
So he is clearly wrong. This effect is much lower than saturated fats effect on cholesterol. In fact, studies Kresser will cite to show dietary cholesterol won’t increase serum cholesterol were studies that increased dietary cholesterol BUT decreased saturated fat. A sneaky way to publish a study saying dietary cholesterol doesn’t increase serum cholesterol.
Now the statement that higher cholesterol doesn’t affect mortality is UTTERLY wrong. I mean, come on! You could write a book on this, and many have been written. Hundreds of studies.
This is why we have cholesterol lowering drugs. I can list so many studies here but let’s go with this recent excellent prospective study on people with low risk followed 10 years.
Saturated fat
Now, the statement that there is ‘no’ evidence that saturated fat increases your risk of mortality is beyond ridiculous. None? Really?
Studies clearly show that reducing saturated fat by switching to monounsaturated fat significantly reduces risk of cardiac event. Likewise, shifting saturated fat to polyunsaturated fat greatly decreases coronary events.
Even replacing saturated fat with whole grains will reduce heart disease. This review showed that replacing saturated fat with carbs didn’t decrease heart disease but DOES decrease risk of death.
Much of the issue may have to do with the food as a whole rather than just looking at saturated fat. Certainly saturated fat coming from meat is more tied to mortality.
Discrepancy?
Now it is vital to understand that there is data that suggests that saturated fat has no effect on cardiac events. How can there be such discrepancy. The main study that demonstrated this, and the most referenced study on the topic is this one.
I suggest you look at where the funding came from for this study.
Now let me explain to you the trick in this study. They were looking to show that saturated fat did not affect heart disease. So, they wanted to eliminate all confounding factors that can contribute independently to heart disease.
In doing so, they controlled for cholesterol. The problem here is the fact that saturated fat, in part, contributes to heart disease by increasing cholesterol. So basically they are removing the key pathological step. What is left are people who are not as affected by saturated fat.
This is called over adjustment. Dr. Stamler provided excellent critique of this article in NEJM.
Bottom line is that the literature certainly suggests cutting back on saturated fat is good for your heart. We know that the Ornish program and Dr. Esselstyn’s program cut saturated fat tremendously and actually reverse heart disease.
Life expectancy
I can go on forever but let’s get to longevity, because at some point I have to get back to my day job.
So let’s go to the question of who lives longer. This is a tough one. Very hard to compare life long vegetarians and lifelong omnivores. So many variables.
The EPIC Oxford trial attempted to compare vegetarians, vegans, and meat eaters. Of note, the meat eaters were low level meat eaters and controlled to be moderate veggie consumers. In other words, the meat eating control was healthier than your average omnivore in England, as evidence by lower mortality rates compared to their compatriots.
Joe Rogan hosted the debate on his podcast
Review
There was in fact a mortality difference though small. Recently the authors did a much larger review.
This exhaustive review showed vegetarians had much lower pancreas and blood cancer but all cause mortality was not lower. How could this be? Well they explain in their discussion that their results are different to the Adventist Health study and this may be because of differences in diet quality between the Adventist Health and the Epic group.
This is CRUCIAL to understand. The Adventist Health Study May be the best population to study for several reasons. First off, the population is very similar. They live in the same area, they practice generally healthy lifestyle, yet they are genetically different.
Many thousands have been placed in their database and followed for many years.
Variables
The authors of the epic study note that one deficit in their study is the fact that there was not a large difference between their meat eaters, and even their high meat eaters were not eating a lot of meat compared to US meat intake.
This is important. If you are doing a study looking at two groups but they don’t differ much with regards to the variable being measured then you won’t see big differences. In fact, the Adventist group had much larger differences between groups.
Also, the Epic vegetarians and vegans were not very healthy eaters. In several studies this group was found to eat about the same amount of fiber, a measly 20 gm, as the meat eaters. Several studies showed that many did not supplement B12 or did not get at least 500mg of calcium. The Adventist group did better in these regards, though still not to the diet I recommend.
Longevity advantage
The Adventist Health Study shows a clear longevity advantage?. These are excellent well controlled studies.
An excellent Meta-Analysis was done on vegetarians and mortality and it showed a definite benefit to cardiovascular mortality and lower cancer incidence.
Of course, there have not been that many studies on vegetarians and longevity because there are not that many vegetarians.
The literature, however, is rich with studies showing that lower meat consumption is associated with lower all cause mortality. I list many in my book but this is perhaps the best review.
