Follow-Up to: Direct Evidence that Vegans have Lower Cancer Rates
Wow – the post on Direct Evidence that Vegans have Lower Cancer Rates was one of my most popular ever. That could have partly been due to my asking people to share it with others – thank you to everyone who did that! And now, please unshare it. 🙁
I wrote the post on Monday evening. This morning (Wednesday) a reader, Dave, commented that after adjusting for BMI, the finding for vegans was no longer statistically significant AND that the authors had not adjusted for physical activity. I had not paid proper attention to either of these facts, partially due to not reading the charts in the study correctly.
The authors found significantly more physical activity among those who did not get cancer and also among the vegans, so it is quite odd that they did not adjust for physical activity. But since they did not, and while this study still shows vegans to have lower cancer rates, I no longer consider the study to be evidence that a vegan diet leads to lower cancer rates, which is the whole idea. I have corrected the original post to reflect this.
I sincerely apologize to everyone for doing such a poor job analyzing the study and then asking people to share it.
This post has a follow-up: