The absorption of non-heme iron is strongly associated with "environmental variables", that is, your overall diet. There are known genetic issues that impact non-heme iron metabolism and this is an area of nutrition that is rather immature so a lot more details is likely to be discovered going forward.brimstoneSalad wrote: ↑Sat Mar 17, 2018 3:22 am The point I was emphasizing is that none of these genetic or environmental variables affect non-heme iron specifically, so this is just an issue of consuming a little more than some other people might need (or extra vitamin C which does affect non-heme, in a good way). And it's not that much more.
My point here is that based on current science you cannot rule out the existence of a subset of the population that will have profound difficulties meeting their iron (and other mineral) needs on a plant-based diet. So if a "meat eater" says they had trouble with iron on a plant-based diet their report is scientifically plausible.
Based on what evidence? I'm not aware of any studies that have been done on vegans with iron issues or that have evaluated the issue of iron needs as a whole in the vegan population. We just have observational studies riddled with survivorship bias.brimstoneSalad wrote: ↑Sat Mar 17, 2018 3:22 am The chances are just very low, and the fix is pretty easy. It can be as easy as switching to a multi with iron instead of one without and drinking OJ with your dinner or something along those lines.
We don't have good studies on the topic, the fact that vegetarian men don't seem to have higher rates of iron deficiency doesn't mean much when people can readily return to eating meat. To study this you'd need to use a longitudinal study (ideally starting in childhood or birth) and track outcomes overtime including dietary shifts.brimstoneSalad wrote: ↑Sat Mar 17, 2018 3:22 am I don't think it's ever something men need to worry about, particularly since we don't see iron deficiency in vegetarian men in the developed world (although men may need to be mindful of zinc consumption).
Some groups recommend that but its not based on rigorous research, its their best guess. Similar with recommendations for zinc and protein, there are some guesses but no good studies. And 1.8 times is hard to achieve for non-menopausal women without supplements. But iron supplements come with some long-term health consequences that aren't entirely understood, for example:brimstoneSalad wrote: ↑Sat Mar 17, 2018 3:22 am IIRC, guidelines recommend vegetarians and vegans consume 1.8 times more iron due to evidence based differences in absorption.
So, this is already accounted for. If a vegan or vegetarian is having trouble, it could make sense to aim for that, and a multi can help.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC340385/
There I'm referring to genetic issues that alter iron metabolism.brimstoneSalad wrote: ↑Sat Mar 17, 2018 3:22 am We know there is: pre-menopausal women with heavy periods.
There are also plenty of people that smoke that ever get lung cancer. Anecdotes from dietitians provide very little information, they are riddled with cognitive bias. And correcting iron issues long-term with supplementation comes with potential negative consequences that would have to be studied as well.brimstoneSalad wrote: ↑Sat Mar 17, 2018 3:22 am There are plenty of vegans who have issues with iron and correct them with diet improvement and supplementation.
I think you underestimate the determination of some vegans and the amount of case study knowledge that exists among dietitians. Not everybody just quits when they experience problems.
But there is a plausible explanation, namely, cognitive bias. Vegan dietitians are more likely to report and remember the positive stories rather than the negative ones. And there is going to be a good deal of selection bias here, people with profound iron issues are likely to just give up on the diet in the first place.brimstoneSalad wrote: ↑Sat Mar 17, 2018 3:22 am There doesn't seem to be a plausible explanation for the absence of case reports on people who were unable to correct iron deficiency from vegan dietitians aside from such cases just not existing or being so profoundly rare nobody with such an issue has sought help.
Confirmation bias is an amusing thing, you can find dietitians (and doctors) promoting all sorts of diets all with "case studies" supporting what they want to believe. Why listen to one over the other? No reason, the focus should be on science not anecdotes. The conversation is de-evolving into anecdotes because there is a lack of research.
The proteins are the same whether they are in the whole food or a mock meat (this isn't entirely true because the processing can alter the proteins a bit), if they increased absorption it should occur in either case. You're speaking as if the proteins in mock meat are perfectly isolated, but that isn't the case. Regardless, since the proteins in meat and legumes, etc are significantly different there is no reason to believe they would have the same impact. You're speculating here, you'd have to test mock meats to see if they had a similar impact.brimstoneSalad wrote: ↑Sat Mar 17, 2018 3:22 am What??? No, precisely the opposite.
The point of the efficacy of that protein is that an impediment to absorption has been removed. The study YOU linked to discussed the same possibility for chicken due to the unusual results.
When have I done that? You asked what I was basing my comment on and I gave you an example (the study cites a variety of other studies as well) The research here is hardly "overwhelming", that is why you had to cite a small study from 40 years ago using a synthetic diet rather than recent research.brimstoneSalad wrote: ↑Sat Mar 17, 2018 3:22 am Cherry picking one small study to disprove the recommendations of professional dietitians based on overwhelming controlled studies isn't very convincing.
Also I never denied that vitamin C can increase iron absorption, rather I suggested the impact appears to be less than the impact seen in meat.
All the studies "count", but studies on complete diets tell you more than studies on single meals or synthetic meals.brimstoneSalad wrote: ↑Sat Mar 17, 2018 3:22 am So which is it? Do only studies on "actual meals" count in your view?
A lot of your response seems to be based on a straw-man, namely, the idea that I'm going against the "consensus" on vitamin-c role in iron absorption despite the fact that I never denied a positive role. You also keep misrepresenting the intent of what I'm citing, for example, never have I suggested that a single study "proves" or "refutes" anything. Now perhaps you just misunderstand my intent which is fine, but why make wild assumptions rather than ask for clarification?