I’m an internal medicine physician who has been vegan since July 2010, and I was shocked how hard it is to find comprehensive, unbiased info about the health effects of a vegan diet. Up To Date, a usually great web-reference for physicians, has practically nothing on the topic. If you search PubMed (the NIH database of medical literature) for vegan studies, over 2,000 come up, but there is no go-to source that sums up what all this research is telling us.
The topic of veganism tends to bring out strong feelings, so I want to make the purpose of this blog totally clear from the beginning. I am only writing about the health effects (good or bad) of a vegan diet. No ethical arguments, no impassioned pleas, no advocacy, no propaganda, just impartial health info. I am going to do my best to sort through all this research and present what we know and be honest about what we don’t. If anything, being a vegan will make me especially vigilant for any health risks. After all, if I’m hurting my body by doing this I want to know!
There is one huge limitation about vegan research that we have to be honest about from the very beginning. The best kind of study is a double-blind randomized controlled trial, which has never (and may never) be done with vegans. It would be almost impossible, and let me explain why. Double blind means neither the scientists or the subjects know who is in the control or study group, which means a person in the study couldn’t know if they were eating a vegan diet or not. I suppose it’s possible for people to eat only non-descript mush given to them by scientists for a few months or years, but I don’t think very many people would volunteer.
What we are left with is “real world” studies, which can give a lot of information, but cannot PROVE cause and effect. All it can show is that two things are associated. Wearing a life jacket is associated with a shipwreck, but it did not cause the shipwreck. So if a study shows that vegans have less heart attacks, maybe it is the vegan diet that caused it, or maybe vegans as a group are more health-conscious (so they are less likely to smoke, be sedentary, etc.).
These limitations are important, but I believe there are some common-sense conclusions we can draw about what being vegan does to the body. I guess a logical place to start is vegan pregnancy, so I’ll start working on that and post what I find out.