A friend of mine shared this story on Facebook today, and the story (and the report it’s based on) is so stupid I feel the need to shred it to pieces. (Not the friend, of course.) Also it maligns my beloved bacon, and I won’t have that. The headline says that bacon and alcohol have been linked to stomach cancer, according to the World Cancer Research Fund.
First of all, we know the problems inherent with every study of diet: Subjects have to self-report, or may be analyzed as a group by how much a region consumes. There’s absolutely no way to control properly for what a person eats outside of very time-limited, very strict lab settings, and of course those can’t give you data on long-term outcomes, so there’s really no such thing as scientifically studying a person’s diet to begin with because there’s no such thing as a controlled experiment. And that’s not even counting the fact that you can’t isolate all the other possible variables.
Analyzing people by region is even dumber, and it appears to be at least one of the methods behind this report based on some of the things mentioned in the article. There is zero methodological validity to analyzing people by region, because the number of variables in play is huge and there’s no controlling for them at all. Call this the “But the French eat X” fallacy. You can’t read any meaning into it.
So to start off with, there’s no such thing as a scientific link between a given food and cancer, because you can’t study such things with any method that could be called science. I know governments and advocacy groups throw money at “studies” like this all the time, but all they are are makework projects for biochemistry grad students. They can get better results in animal testing of course; some that could be called science because they can account for variables there. But mice and humans have a very wide gulf between them, which is why whenever you read news about a medical breakthrough and the article says “in mice”, you should stop holding your breath and pretend you didn’t read it in the first place. You can bet 99% of those breakthroughs never survive in human trials. So it is with diet. (Have you heard that very low calorie intake can cause a huge boost to your lifespan? Based on research in mice, and repeated ad nauseum. It didn’t hold up in humans, but it still gets repeated anyway. There are lots of reasons to watch how much you eat, but living longer isn’t directly one of them.)
Here’s where the junk science gets even junkier. The World Cancer Research Fund says right up front that they analyze research around the world—that is, they’re not doing their own original research. (Or maybe they’re doing some of that too, but it doesn’t appear to be their core focus.) The article even repeats this. That means that what they’re reporting is what’s called a meta-study, and meta-studies are the very junkiest of junk science. These aren’t research at all, but merely collecting multiple research papers on a subject and analyzing them for trends to draw broader conclusions. Anyone familiar with the scientific method knows this is like collecting dozens of history textbooks with the goal of using them to open a time portal to ask George Washington what he had for breakfast. No doubt the WCRF thought they really did find something, and this was a sincere effort to get the word out, but it makes their methods no less wrong.
Cancer is serious business, so I have no ill will toward the WCRF and wish them the very best of luck in advancing human knowledge toward a cure. But it bothers me that they operate by doing meta-studies, which can’t advance knowledge at all. Heck, it’s right in their mission statement that comes up when you Google them. Meta-studies are absolute garbage; they can’t help anyone learn anything except how not to do science. At best they have no value; at worst, and this is most often the case, they lead science on wrong paths and impede real investigation.
Analyzing research around the world means nothing unless you’re working to reproduce, question, or debunk that research, because those are the only reasons to analyze research at all. (I’d like to hope some of what the WCRF does is exactly that, looking for flawed research to cut apart so that other researchers will step up and do better. All science is skepticism.) You can’t draw conclusions without data, and a study is not data; it’s output. When an experiment is done right, you get to see the raw data, the process used to analyze that data, and the conclusions drawn from it if any. Those conclusions are not raw anymore, and can’t be used as data points in another study. Not only that, but you also can’t combine raw data points from different studies because you can’t know for sure they used the exact same methodology or that a new variable (or ten) doesn’t exist between the different subject groups. This is not only basic logic, basic science, but basic information theory.
So what does this mean for bacon and alcohol? It means nothing one way or the other, because this report is junk. If there truly were a link between bacon and stomach cancer, the methods used by the WCRF to find it couldn’t tell you that. Those same methods could just as easily tell you that liking the color yellow makes you five times more likely to be a serial killer, because the science involved is not science.
Incidentally, another way you can tell this article is BS is that they equate the increased risk from eating “processed foods” (and seriously, what in the frell does that even mean?) with the increased risk from smoking. Smoking. You know, that thing that so reliably and predictably causes cancer that nothing else we know about—except for maybe certain chemicals, high-dose radiation, and an excess of ultraviolet light—comes close. This is like saying that glancing at a road sign increases your risk of a car accident as much as driving blind drunk, in a snowstorm, with one eye closed, while texting. The result doesn’t pass the sniff test. You wouldn’t need a meta-study or even a real study to tell you this if it were any kind of true, because it’d be like having a neon sign flashing over ten generations’ worth of demographic data.
Now if you’ll excuse me, there’s some leftover bacon with my name on it.