The Healthy User Bias and the Unhealthy User Bias
The healthy user bias is such an important point to note that, when we’re looking at epidemiology studies, in these observational studies we always need to consider the possibility that, whether we’re looking at increased consumption of fruits and vegetables or increased consumption of fiber, those can also be often associated with other healthy behaviors.
And maybe it’s the other healthy behaviors that are benefiting those people, rather than the fruits and vegetables or rather than the fiber.
There are some really elegant studies that suggest that’s very much the case. For example, there’s a study from Britain called ‘The UK Shoppers Study’, where they looked at vegetarians and they compared the standard mortality ratio of vegetarians to the general population. And what they found is what we see generally in Westernized populations, that vegetarians have a lower standardized mortality ratio than the general population.
Then they did a really smart thing, they compared the death-rate ratio (the comparison of the rate of death) of those vegetarians to non-vegetarians who also did healthy behaviors.
And they found that people who exercised, who didn’t smoke, who got sunlight and who did other healthy behaviors, low and behold, same death-rate ratio!
So all the benefits of being a vegetarian went away when they compared it to someone who had healthy behaviors.
This is probably what we’re seeing in all of these studies, it’s fake news, it’s unfair reporting and this misleading reporting, this is a real problem confounding these studies.
On the flip-side there’s also such thing as an unhealthy user bias!
The fact that when we see studies that say meat is bad for you, that meat is associated with decreased longevity, those are the James Dean types who are like ‘you know what, just screw it all, I’m gonna eat meat and I’m gonna smoke and ride my motorcycle and not exercise’ because in the USA and in the Westernized world, we’ve been told meat is bad for you, so who eats meat? People who are rebels!
Then in Asian countries people have been told, ‘meat is what rich people eat’, so the people who eat meat over there are seeing it as a health food or a reward or a status symbol.
But in the West we only see meat as a rebellious food. You’re gonna smoke a cigarette, eat a hamburger, eat some french fries and have a coke, because you know what, you’re fed up with everything. And that is a type of behavior that really makes it hard to separate whether it was the effect of the meat or everything else that person was doing.
Source: Sisson, Mark, guest. Saladino, Paul, guest. Baker, Shawn, guest. “Part 47 – The Great Meat Debate w/ Mark Sisson, Dr. Paul Saladino, & Dr. Shawn Baker” Peak Human, 18 July 2019. https://www.peak-human.com/home/the-great-meat-debate-with-mark-sisson-dr-paul-saladino-and-dr-shawn-baker