Vegan Nutrition Testing Project: Interim Report

Although I have no doubts that iron deficiency is a problem, I do not think the evidence linked for this is particularly strong backing for it having massive effects. In particular, estimating the cognitive impacts of anything from one study that hits marginal statistical significance with a massive estimated effect size (0.5 standard deviations)  seems likely to lead to a wildly inaccurate estimate of the true effect. This is because this study possesses all the hallmarks of low statistical power interacting with publication bias.

Furthermore, given that the the other studies appear to have small samples sizes (note: I am an economist, not a medic) and the p-values are not far off 0.05, I would be worried about publication bias exaggerating any effects there as well, especially as I suspect studies conducted fifteen to twenty years ago were unlikely to be pre-registered.

To convince me of an effect size, I would want to see a study with p<<0.01 or a meta-analysis of RCTs that addresses the issue of publication bias.

I was even both iron deficient and vitamin D deficient while taking a multivitamin with 100% RDA of both iron (18mg amino acid chelate) and vitamin D (although as D2). I continue to take the multivitamin, on top of separate iron and vitamin D3 supplements, and last I checked (a few years ago), I had normal blood levels. The testing was prompted by blacking out when I'd get up too fast. For the past few years, I've been taking just over the upper limit in iron from supplements alone (46 mg/day, the UL is 45). Your previous post prompted me to check if this was safe, but I think it's fine since the iron doesn't absorb as well as heme iron, but maybe I should get tested again and see if I can cut back a bit.

I had been giving blood regularly, too, before I started to black out, but even when I stopped, my ferritin levels didn't really recover to normal and I kept blacking out, so I added the iron supplement.

The tests you're using sound quite involved. In the UK at least, there are simple and cheap blood tests you can order for vit D and iron e.g. here and here respectively, which I thought might be useful for people to know. I don't know how reliable they are, though. There look to be home vit B12 tests that are more expensive and I've not used one myself.

Thanks for the project and the write-up!

Does anyone know any good sources to help someone going vegan to figure out:

• which deficiencies to worry about
• how to counter them (not just supplements, which I would like to avoid relying on when possible)

Borderline D is common enough in the general population that I wouldn't draw any clear conclusions about the effect of diet here.

Am not vegan, but have had B12, iron, and D tests done through insurance. The cost was significantly lower than private testing, and my insurance picked up the bulk of the cost to boot. "Vegan patient -- or any patient, really -- complains of some fatigue" should be a valid reason to run those tests from the perspective of any decent US insurer, and who isn't fatigued from time to time? Can't speak for other countries, but since everyone should have a primary-care doctor they see at least every few years anyway, it might be more efficient to push the ops work and test expense largely onto the insurer here.