"The vegan diet will kill me because heme iron!!!" said a meat eater

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carnap
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Re: "The vegan diet will kill me because heme iron!!!" said a meat eater

Post by carnap »

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.
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.

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.

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.
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 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).
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 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.
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:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC340385/

brimstoneSalad wrote: Sat Mar 17, 2018 3:22 am We know there is: pre-menopausal women with heavy periods.
There I'm referring to genetic issues that alter iron metabolism.

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.
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 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.
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.

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.

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.
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 Cherry picking one small study to disprove the recommendations of professional dietitians based on overwhelming controlled studies isn't very convincing.
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.

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.
brimstoneSalad wrote: Sat Mar 17, 2018 3:22 am So which is it? Do only studies on "actual meals" count in your view?
All the studies "count", but studies on complete diets tell you more than studies on single meals or synthetic meals.

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?
I'm here to exploit you schmucks into demonstrating the blatant anti-intellectualism in the vegan community and the reality of veganism. But I can do that with any user name.
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brimstoneSalad
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Re: "The vegan diet will kill me because heme iron!!!" said a meat eater

Post by brimstoneSalad »

carnap wrote: Sat Mar 17, 2018 3:28 pm The absorption of non-heme iron is strongly associated with "environmental variables", that is, your overall diet.
Absolutely, but we also have a good idea of what those are, and it's not plausible that typical advice would not work.
carnap wrote: Sat Mar 17, 2018 3:28 pmThere 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.
Genetic issues that have wide-ranging metabolic implications. In order to qualify, it would have to be somebody who would do just fine with some heme iron and not have medical issues but has a genetic inability to handle non-heme iron which is not easily resolved by dietary intervention to increase non-heme iron or absorption, and that's not plausible.

I'm not saying it's impossible, but there's not even a known example of that in obligate carnivores like cats, not a genetically engineered mouse that expressed such a trait, etc. And not one case report of that.
carnap wrote: Sat Mar 17, 2018 3:28 pmMy 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.
I'm not saying I know it's not possible, but it isn't plausible.

If I head hooves in the park, I'm going to think horse not zebra. If I hear scratching at night, I'm going to think rat climbing in the wall, not a cryptid monster.

carnap wrote: Sat Mar 17, 2018 3:28 pmSo if a "meat eater" says they had trouble with iron on a plant-based diet their report is scientifically plausible.
What is most plausible is that they did something wrong, and that the issue would be easily resolved by a properly planned vegan diet.
The idea that they have some rare genetic anomaly that happens to affect only this is not plausible.

Now if they had expert help and this was published in a case study, sure; you eliminate the most probable explanation, and others become more plausible.
If even one other species exhibited this, it would be more plausible too because we'd at least know it can happen.
I'd call being unable to synthesize taurine unlikely in a human, but plausible on the grounds that we know some obligate carnivores can't and the genetic mechanisms without serious deleterious effects on a taurine containing diet are clear.

I'll try to address the rest later.
I appreciate that you put a lot of time into your arguments, and this is valuable as an exercise in debate, but I really think you need to more carefully assess what you regard as plausible because I think personal biases may be playing in here when the mechanism something like this would work by is by no means clear and we have no examples of it. Iron metabolism appears to be pretty primordial.
I'm interested in knowing when things could go wrong with a vegan diet, because that helps us identify fixes, but I think this is barking up the wrong tree.
carnap
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Re: "The vegan diet will kill me because heme iron!!!" said a meat eater

Post by carnap »

brimstoneSalad wrote: Sun Mar 18, 2018 4:26 am Absolutely, but we also have a good idea of what those are, and it's not plausible that typical advice would not work.
We know of some issues but the science is immature and we don't know how various genetic factors interact with environmental factors.
brimstoneSalad wrote: Sun Mar 18, 2018 4:26 am Genetic issues that have wide-ranging metabolic implications. In order to qualify, it would have to be somebody who would do just fine with some heme iron and not have medical issues but has a genetic inability to handle non-heme iron which is not easily resolved by dietary intervention to increase non-heme iron or absorption, and that's not plausible.
That would be the extreme and by no means the only issue. Firstly heme vs non-heme isn't the only factor, the bio-availability of iron from animal sources is much higher than plant sources (that applies to both heme and non-heme iron) and meat enhances overall absorption of iron in the diet. As such there are a large number of genes that could potentially impact iron metabolism on a vegan diet and this type of research is in its infancy.

For me the key question here is whether there is a subset of the population that will have trouble meeting iron needs on a "well planned vegan diet" but not on a balanced omnivorous diet. Whether or not such a person will respond to medical treatment doesn't negate the underlying issue, if people have to undergo medical observation to maintain their needs on a vegan diet that doesn't make a good case for the diet for that person.

What I'm suggesting here is entirely plausible based on the existing science, the issue here is that the existing science is immature and we don't have good studies that have evaluated the impact of vegan diets on people's ability to meet their nutritional needs and so on. What little research exists today is almost all observational in nature.


brimstoneSalad wrote: Sun Mar 18, 2018 4:26 am What is most plausible is that they did something wrong, and that the issue would be easily resolved by a properly planned vegan diet.
The idea that they have some rare genetic anomaly that happens to affect only this is not plausible.
Without research we don't know how "rare" such an issue would be, the existing research provides little information since it almost all suffers from suvivorship bias.

An improperly planned diet is certainly one potential explanation, but you can get a sense of someone's diet by asking questions. This also brings up another issue, namely, the feasibility of the diet for the person. Let's say someone having issues could resolve those issues with some specific dietary interventions. But that involves two issues: 1.) The person has to discover the dietary interventions which will require experimentation, medical follow-up and so on. 2.) The dietary intervention would need to be feasible within their lifestyle.

Both of these are big barriers, why should someone self-experiment and potentially negatively impact their health to maintain a vegan diet when they know everything worked fine with an omnivorous diet? And the second issue could mean a diet that is impractical for the person to follow or involves foods the person just doesn't enjoy.

brimstoneSalad wrote: Sun Mar 18, 2018 4:26 am carefully assess what you regard as plausible because I think personal biases may be playing in here when the mechanism something like this would work by is by no means clear and we have no examples of it. Iron metabolism appears to be pretty primordial.
Everyone has "personal biases" so when you say something like this it suggests that you're somehow immune to an aspect of human psychology. The only claim I'm making here is that we lack sufficient research to know the long-term impact of vegan diets on iron metabolism in the population at large. As such you cannot claim its implausible that there are people out there that will have major difficulties meeting iron needs on a vegan diet.

Iron metabolism is "primordial", but that doesn't mean there isn't genetic variation in iron metabolism. We know there is, we just don't know the implications and degree.

Also while this thread is about iron, iron is one of the better understood nutrients and we also have an easy method to test for sufficiency. Zinc, calcium, etc sufficiency are much more difficult to determine and we have no way of determining a host of other issues. That means if someone has an issue with a vegan diet after they try the obvious they are going to be pretty much in the dark about potential interventions.
I'm here to exploit you schmucks into demonstrating the blatant anti-intellectualism in the vegan community and the reality of veganism. But I can do that with any user name.
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