Repudiating what “obligate carnivore” means—Kindly, but stridently, we have to correct folks that obligate carnivore stems from observation, not a diet requirement
Could you provide a source for this? In biology, “obligate carnivore” means “obligate meat eater”. They cannot get sufficient nutrition from plants alone. This doesn’t rule out an artificial diet providing the missing nutrients, or someone incorrectly classifying a non-obligate carnivore as obligate due to bad data. But it does not mean “based on observation”. Your description holds for the order carnivora, but that is not synonymous with carnivore because biology as a field is dumb.
In your Opportunities section you suggest doing more rigorous RCTs on vegan cat diets (which I agree with), but the rest of your post feels like you considered the question settled. You link to sources claiming that result, but it feels like an aside rather than your focus. I wish you had gone into these in detail, because the papers look quite bad to me.
The main website you link to links to a review article in which only 4 studies with a combined 39 subjects use blood tests rather than owner reports, and more than half of those were given vegetarian diets, not vegan (even though the table header says vegan). The only RCT didn’t compare with carnivorous diets. This is already not nearly enough to consider the question settled, even if the studies strongly supported no-meat diets.
But also I can’t find where this paper actually reports results for cats in an organized way? There are tables for dogs, but for cats there are only text descriptions. These mentions multiple problems, albeit one of them preventable. And again, these cats were mostly on vegetarian diets, not vegan (and not necessarily for very long, although 2 weeks was long enough to develop problems)
It very much looks like the authors of this review article wanted to say no-meat diets were harmless for cats, but the data went so strongly against their point they couldn’t manage it.
I’m confused why the study both says this as you’ve highlighted, but then in the discussion and conclusion it says:
Discussion
The finding of this study suggests, on the face of it, that there is very little evidence of major adverse effects resulting from the feeding of vegan diets in dogs or cats. The majority of the animal-based parameters were within normal reference ranges and when there were deviations from normal reference ranges, there were rarely clinical signs reported alongside the finding. In addition, whilst the broad literature in this area commonly makes reference to concerns around nutrient deficiencies, such as that of taurine, folate, and cobalamin, there were a limited number of studies that measured these outcomes (generally, only two studies for key outcomes), with limited evidence of these deficiencies arising (with some of the alterations likely being attributable to confounding; for example, as a result of secondary disease, e.g., giardiasis in a dog). These conclusions should, however, be interpreted cautiously, given the breadth and quality of the evidence presented as described below
Conclusion
This review has found that there is no convincing evidence of major impacts of vegan diets on dog or cat health. There is, however, a limited number of studies investigating this question and those studies available often use small sample sizes or short feeding durations. There was also evidence of benefits for animals arising as a result of feeding them vegan diets. Much of these data were acquired from guardians via survey-type studies, but these can be subject to selection biases, as well as subjectivity around the outcomes.
Except, as you pointed out, convincing evidence of major adverse effects resulting from feeding cats vegan diets appear to have actually been observed as stated by the same authors saying it has not been observed. I notice I am confused given I do not think the paper is authored by bad actors.
Part I want to highlight in image below: Cats were supplemented. So the adverse affects you highlighted it sounds like you could prevent with supplements. Is this the only reason the authors conclude cats can be fed a vegan diet? But then it sounds like a better and more responsible conclusion by the authors would have been: it seems theoretically possible that a vegan cat food could exist with correct supplementation, but no healthy vegan diet for cats exists yet (all studies show specific supplementation thus far is neccesarry for existing vegan foods otherwise your cats might very quickly develop major adverse health outcomes—am I wrong?).
They also highlight they didn’t review the suitability of the supplements? What does this mean—“suitability”? Cant find an answer for that.
Could you provide a source for this? In biology, “obligate carnivore” means “obligate meat eater”. They cannot get sufficient nutrition from plants alone. This doesn’t rule out an artificial diet providing the missing nutrients, or someone incorrectly classifying a non-obligate carnivore as obligate due to bad data. But it does not mean “based on observation”.
I could have the official definition wrong—I edited the post. I’m thinking about it colloquially and repudiating how it’s conceived for example here.
I agree that the paper you highlighted is not making its case strong nor clear.
This is not a semantic issue you can fix with a minor edit. Your post rests on the assertion that cats can be healthy when fed an exclusively plant-based diet, and that these diets are already available. You are sure enough of this to say we should “stridently correct” people who believe they can’t.
You can claim people are wrong to categorize cats as obligate carnivores, but you need to demonstrate that with evidence, which you absolutely have not done. You say the best evidence is survey based, but with such a motivated population and minimal reporting I consider it meaningless.
Even in this comment you act as if the linked reddit comment (copied below) is obviously false, but it is using obligate carnivore correctly and you have provided minimal evidence to even suggest reconsidering that designation.
My steel man here is that it might be possible to render cats vegan with new technology, and you think it’s worth doing. I don’t necessarily disagree with that, but it is such a different claim than “cats are not obligate carnivores and can all happily live on a vegan diet today”.
Reddit comment Karthik links to:
> Hello there. Pet nutritionist here, trust me when I say cats ARE obligate carnivores. If you feed them a vegan diet they WILL die slowly and painfully, no ifs ands or buts. If you cannot cope with the idea of your cat eating what it needs to in order to survive. Give it up
The argument isn’t solely based on the survey data. It’s supported by fundamentals of biochemistry, metabolism, and digestion too. I won’t presume to know your biology knowledge. Earlier, you said “biology as a field is dumb”, which may or may not be indicative of much personal study of biology. So I apologize if this is over-explaining, but I feel that I may have glossed over it when making the post:
Mammals such as cats will digest food matter into constituent molecules. Those molecules are chemically converted to other molecules—collectively, metabolism--, and energy and biomass (muscles, bones) are built from those precursors. For cats to truly be obligate carnivores, there would have to be something exceptional about meat: (A) There would have to be essential molecules—nutrients—that cannot be sourced anywhere else OR (B) the meat would have to be digestible in a way that’s not possible with plant matter.
(A) is very easy to correct for. Just test formulations for missing nutrients (molecules) and add them. So far, there are no “special” meat molecules that can’t be sourced from elsewhere. (B) is making a more digestible formulation. If we extract pea protein and measure the digestibility, we’ll know if it’ll work for a cat or not.
On (A), AAFCO is setting this already with their nutritional guidelines, e.g. minimum amount of proteins, vitamins, etc. On (B), part of the ingredient testing is making sure the food is digestible for cats (also testing for toxicity).
So any plant-based food that passes AAFCO guidelines is nutritionally complete for cats. Ami does, for example.
One of my points is that people’s assumptions about carnivory fail to consider biochemistry. Yes, the formal scientific studies are lacking, but it really shouldn’t matter based on what’s known about more fundamental biology. Do we need long term studies to absolutely know that Yellowclothea people are safe to wear purple?
I agree that more formal studies higher on hierarchy of evidence would convince folks, seemingly like yourself. And to that point, I advocate for more of it. But given what I’ve researched and what I know about biology, I would feel comfortable raising a cat vegan healthily and recommending others to do the same.
I have a BA in biology. “Biology is dumb” was an attempt to be cute about the inherent messiness of living organisms and attempts to classify them.
You say you’ve done research satisfying you that this is all biochemistry and we know everything we need. Can you write that up? How are we sure we’ve identified every useful nutrient? How do we know the bioavailability tests are any good? Without that this is still just an asserton, and a fairly surprising one given the state of human nutrition.
You say you’ve done research satisfying you that this is all biochemistry and we know everything we need.
To be clear, this is not what I’m arguing. Biochemistry research is never complete. I’m arguing that it’s safe to feed cats vegan based on what’s known.
Can you write that up?
Here’s the AAFCO list of required nutrients for cats and what I view as authoritative (pages 13-14):
How are we sure we’ve identified every useful nutrient? How do we know the bioavailability tests are any good?
I’m not sure. But these questions persist for Fancy Feast and any other meat cat food as much as they apply to vegan cat food. Are we sure they have every useful nutrient and that the measured bioavailability is good?
Okay, it sounds like your argument is “vegan cat food is capable of meeting the same standard as meat-based food”.
From skimming the AAFCO document it’s not obvious to me AAFCO thinks meeting its standard is sufficient for health (see screenshot below, from page 2). Perhaps there is something I missed, but I have put a lot of time into reading papers I found shoddy and you didn’t find worth defending, so I would like to be sure this why you believe what you believe before investing more time checking it out.
Okay, it sounds like your argument is “vegan cat food is capable of meeting the same standard as meat-based food”.
Indeed.
From skimming the AAFCO document it’s not obvious to me AAFCO thinks meeting its standard is sufficient for health (see screenshot below, from page 2).
As you pointed out earlier, we don’t know everything that we could know. What do you propose we do? It sounds like your concerns are with food testing for cats period, and they’re not specific to the vegan formulations.
My stance is that if it’s okay to feed cats meat-based food, then it’s fine to feed them vegan food.
Feed animals close to their natural diet while researching how to do better. You dismiss this as “appeal to nature”, but I would describe it as “the burden is on the attempt to change the default”.
> It sounds like your concerns are with food testing for cats period
I assure you I am at least as obnoxious about human nutrition testing, which is better studied and features a more adaptable subject.
Feed animals close to their natural diet while researching how to do better. You dismiss this as “appeal to nature”, but I would describe it as “the burden is on the attempt to change the default”.
“Meeting nutritional requirements” is a far better default standard than what’s “natural”. Few problems with the “natural” standard:
Retail based meat cat food is far from what’s “natural” as I covered in the post.
What’s “natural” isn’t more equivalent to what’s healthy. Is a diseased bird corpse more “natural” than nutritionally-complete vegan cat food? Probably. Healthier? Hmmmm.
“Natural” is imprecise and hard to make actionable. How would an organization like AAFCO put that into words and regulations?
I assure you I am at least as obnoxious about human nutrition testing, which is better studied and features a more adaptable subject.
Yep, human nutrition is better studied. There’s more funding and more interest in the subject.
As discussed before, we’re both in agreement for more studies. Funding is needed.
I think when she said “natural diet” she didn’t mean to invoke the naturalistic fallacy.
She meant the diet that we have the most empirical evidence doesn’t harm/kill them. We have some empirical evidence that vegan diets appear to quckly give cats major bad health outcomes without supplementation? The first comment in this thread by Elizabeth pointed this out.
We don’t have empirical evidence of the same happening with meat-based diets. So modern nutritionally complete meat-based diets presently have a 100%-wont-cause-major-adverse-health-outcomes rate. Is this not what the studies seem to show?
What’s “natural” isn’t more equivalent to what’s healthy. Is a diseased bird corpse more “natural” than nutritionally-complete vegan cat food? Probably. Healthier? Hmmmm.
No, but consider statistical averages rather than semantic absolutes. If you were to consider all possible meals a cat could reaonably be fed today. On average, it seems reasonable to suspect that they would be healthier if more of those meals were meat-based than plant-based. This is an empirical question, not a semantic one. The nutritionally-complete vegan cat food might be better than the diseased corpose (one single comparison). But having nothing but the nutritionally-complete vegan cat food might be far worse than nothing but meat (statistical average across many samples).
Given how nascent the field is and how we’re only just finding out what supplementation we might have to give cats, it seems like if we were to tell everyone to feed their cat vegan food that we’d probably get a lot of cats with bad health outcomes.
And this would be pretty bad optics-wise for the vegan movement.
She meant the diet that we have the most empirical evidence doesn’t harm/kill them.
We don’t have empirical evidence of the same happening with meat-based diets.
Do we have empirical evidence that a specific meat-based food is consistently safe over many years? My understanding is that many change constantly.
So modern nutritionally complete meat-based diets presently have a 100%-wont-cause-major-adverse-health-outcomes rate. Is this not what the studies seem to show?
Best we can do is what AAFCO and FDA already do. AAFCO sets nutritional guidelines and ingredient requirements. FDA regulates the safety.
We have some empirical evidence that vegan diets appear to quckly give cats major bad health outcomes without supplementation? The first comment in this thread by Elizabeth pointed this out.
Why is that diet representative of for example nutritionally complete Ami, which has been around for years? Isn’t it much better to just defer to AAFCO’s and FDA’s standards, which Ami meets?
The most parsimonious explanation is that the lack of supplements was the problem, not the “vegan”-ness. If I get sick from my potato chip diet, it doesn’t mean I should avoid a plant-based diet with all required nutrients.
If you were to consider all possible meals a cat could reaonably be fed today. On average, it seems reasonable to suspect that they would be healthier if more of those meals were meat-based than plant-based.
Based on what? I don’t intuit this at all. Furthermore, we’re not saying any plant ingredients. We’re saying the ones that meet nutritional, toxicity, and digestibility requirements for cats.
Both you and Elizabeth have offered something fairly distinct from AAFCO’s/FDA’s standards. And so far, I’m finding neither to be better.
Given how nascent the field is and how we’re only just finding out what supplementation we might have to give cats
It’s not nascent. AAFCO has been providing guidance on the nutritional requirements for cats for decades.
For me: I agreed with you and felt like my mind was being changed to being pro-vegan-cat—until I read Elizabeth’s comment pointed out the issues in the study. So for me it is mostly because you haven’t engaged with that specific comment and pointed out why the concerns that are highlighted in her screenshots (from the actual study!) are not something that I need to worry about.
Convince Elizabeth and you, by proxy, convince me I’m pretty sure.
The most parsimonious explanation is that the lack of supplements was the problem, not the “vegan”-ness.
Sounds reasonable to me. I didn’t say that a lack of supplementation wouldn’t solve it. I argued that meat would. Arguing for X doesn’t mean I argued for ~Y.
The study came out January of this year. That’s pretty recent.
Does a nutritionally complete vegan cat food exist yet that takes everything learnt from this study and all the studies it references into account without need for additional supplementation? If yes, I’d want to see a study where cats are fed it first before I place my own cats exclusively on it. Till then I’d probably be too paranoid to feed them a fully vegan diet.
Why is that diet representative of for example nutritionally complete Ami, which has been around for years? Isn’t it much better to just defer to AAFCO’s and FDA’s standards, which Ami meets?
I’m confused. By “that diet” you mean to say the diet that was tested in the actual study you use as support for your claims should not be taken as an example of something nutritionally complete?
Ok, after trying to figure out what “Ami” was I see in your post you refer to it as vegan cat food that exists on the market.
Apparently it has also been around for 20 years after a quick Google search. Now I’m just hyper-confused why Ami wasn’t used in the Domínguez-Oliva et al. Study instead.
Thanks Cornelis, I sincerely appreciate the good will shown.
For me: I agreed with you and felt like my mind was being changed to being pro-vegan-cat—until I read Elizabeth’s comment pointed out the issues in the study. So for me it is mostly because you haven’t engaged with that specific comment and pointed out why the concerns that are highlighted in her screenshots (from the actual study!) are not something that I need to worry about.
I conceded on Domínguez-Oliva et al., and Elizabeth’s concerns were entirely valid. However, it’s one study and one diet, and I felt that Elizabeth was ignoring the basis of nutrition and biochemistry that I emphasized throughout the post. Thanks for highlighting that the food was lacking necessary, known supplements. That was a key point that would have been helpful to broach earlier.
A RCT study will likely be just a formality for something like the Ami vegan cat food. And yes, it’s frustrating that this hasn’t been done/published yet! As I understand from Andrew Knight, there’s a better study coming out this year.
Convince Elizabeth and you, by proxy, convince me I’m pretty sure.
I haven’t found Elizabeth willing to falsify their thinking as much as you and perceive general antagonism and defensiveness.
(A) There would have to be essential molecules—nutrients—that cannot be sourced anywhere else OR (B) the meat would have to be digestible in a way that’s not possible with plant matter.
Nutrition is hella complicated. As someone who drinks a ton of Soylent, I am often surprised by how my own view of “it shouldn’t matter as long as the molecules—when you break it down—are the same” is overly simplistic. If you have food substance A and food substance B and their molecules are organized differently, then even if you were to break them down and get the same base nutrients, this does not mean they are equally healthy for you. This is because their different initial arrangement can lead to different biochemical cascades. I recently learnt that antimicrobial mouthwash might influence your mouth bacteria to such a degree that is leads to a decrease in NO production to the point that your blood veins don’t dilate as much = causally linked to increased arteriosclerosis. There is an entire scientific journal just dedicated to this pathway. See here.
I would never have intuitively thought this could happen. I can increase my risk of heart disease by nuking the bacteria in my mouth? Lol… wat?
It really is not a stretch to imagine that even if meat and vegan food appears to be nutritionally complete and—if broken down -they yield similar macronutrients—that still because the vegan food has a different composition before being broken down that different biochemical pathways are kicked off leading to harm that the meat-based one does not lead to. Something weird and unexpected like the NO pathway could explain why cats on vegan diets still get health issues as the pro-vegan study Elizabeth linked to shows.
An escape hatch from this would of course be lab grown meat that is to the molecule identical to meat. In that case it wouldn’t make sense for one to be any different from the other because they are not only to the molecule identical, but also to the molecules are arranged the same way before being broken down.
So my read is you haven’t considered option C: There could be an essential arrangement of molecules in meat before they are broken down, that currently cannot be sourced elsewhere (not until we get lab grown meat anyway).
Something weird and unexpected like the NO pathway could explain why cats on vegan diets still get health issues as the pro-vegan study Elizabeth linked to shows.
But we have the same uncertainty with retail meat-based cat food, which I’ve highlighted is quite distinct from what cats evolved on.
An escape hatch from this would of course be lab grown meat that is to the molecule identical to meat.
I don’t understand the obeisance to molecularly-exact meat. Evolution doesn’t select for health and well being. It selects for propagation for a specific niche in a specific environment. Our goals with domestic cats are different than what evolution optimized for.
Consider human evolution. For most of it, life expectancy was far lower than today. The diet of prehistoric times isn’t by default aspirational. Instead, current nutrition studies focus on health outcomes, e.g. life expectancy, blood pressure, rate of obesity, etc.
So recommendations focus directly on cause (food eaten) and effect (health outcomes). And that’s what we should do with cats. We should not put meat on a pedestal and beeline for that.
But we have the same uncertainty with retail meat-based cat food, which I’ve highlighted is quite distinct from what cats evolved on.
Actually, I think we don’t have the same uncertainty. Those products have been iterated on for a far longer time than vegan cat food—including multiple FDA recalls as you pointed out. We’ve had much more of a “trial-by-fire” of retail meat-based cat food over a longer period of time.
Though in the other comment you pointed out Ami, which given it has existed for 20 years, I imagine has gone through the same trial-by-fire. A new post that does nothing but focus on the evidence that Ami is fine for your cat would probably convince a ton more people. As I mentioned in my other comment I’m very confused why Ami wasn’t used in the Domínguez-Oliva et al. Study instead.
I don’t understand the obeisance to molecularly-exact meat.
I’m not interested in molecularly-exact meat. I’m interested in what—via strong empirical evidence—we know wont harm my cat.
Our goals with domestic cats are different than what evolution optimized for.
Couldn’t agree more, which is why, if we get enough empirical evidence that some particular vegan meal will be ay-ok for cats I’m all aboard.
It is worth adding that I do think we have enough empirical evidence to place dogs on a vegan diet without issue. But my read of the study is we’re not there with cats yet. I really don’t understand why the study authors make the same conclusion for both cats and dogs. The evidence appears to clearly be vastly stronger for dogs than it is for cats.
We should not put meat on a pedestal and beeline for that.
We should put empirical evidence on a pedestal and while truth-seeking be neutral about whether that includes or excludes meat.
Thanks Cornelis, I agree about the empirical evidence. And indeed, emphasizing Ami and how long it’s been around would have obviated a lot of confusion here.
We seem to disagree about (1) the variance of meat-based retail products versus vegan ones and (2) whether or not the “trial-by-fire” standard is more helpful than just simply the criteria that AAFCO/FDA defines regarding nutritional, toxicity, digestibility, and safety.
(1) Sounds like your priors for the intra-variance of meat-based cat food are lower than the inter-variance between validated meat and vegan cat food. I don’t share these same priors, and the best I can offer is Chapter 6 of After Meat where I explain in detail how I think about nutrition including the fungibility of food. Long story short, I really don’t think there’s anything special nutritionally about meat that can’t be recapitulated elsewhere, but I understand that not everyone has that intuition.
(2) AAFCO updates their standards in light of new evidence. The “trial-by-fire” is baked into their standards. And I suspect if we had similar priors regarding (1), this point may be moot.
But I appreciate your good faith, and I’ll leave it here.
Could you provide a source for this? In biology, “obligate carnivore” means “obligate meat eater”. They cannot get sufficient nutrition from plants alone. This doesn’t rule out an artificial diet providing the missing nutrients, or someone incorrectly classifying a non-obligate carnivore as obligate due to bad data. But it does not mean “based on observation”. Your description holds for the order carnivora, but that is not synonymous with carnivore because biology as a field is dumb.
In your Opportunities section you suggest doing more rigorous RCTs on vegan cat diets (which I agree with), but the rest of your post feels like you considered the question settled. You link to sources claiming that result, but it feels like an aside rather than your focus. I wish you had gone into these in detail, because the papers look quite bad to me.
The main website you link to links to a review article in which only 4 studies with a combined 39 subjects use blood tests rather than owner reports, and more than half of those were given vegetarian diets, not vegan (even though the table header says vegan). The only RCT didn’t compare with carnivorous diets. This is already not nearly enough to consider the question settled, even if the studies strongly supported no-meat diets.
But also I can’t find where this paper actually reports results for cats in an organized way? There are tables for dogs, but for cats there are only text descriptions. These mentions multiple problems, albeit one of them preventable. And again, these cats were mostly on vegetarian diets, not vegan (and not necessarily for very long, although 2 weeks was long enough to develop problems)
It very much looks like the authors of this review article wanted to say no-meat diets were harmless for cats, but the data went so strongly against their point they couldn’t manage it.
I’m confused why the study both says this as you’ve highlighted, but then in the discussion and conclusion it says:
Except, as you pointed out, convincing evidence of major adverse effects resulting from feeding cats vegan diets appear to have actually been observed as stated by the same authors saying it has not been observed. I notice I am confused given I do not think the paper is authored by bad actors.
Part I want to highlight in image below: Cats were supplemented. So the adverse affects you highlighted it sounds like you could prevent with supplements. Is this the only reason the authors conclude cats can be fed a vegan diet? But then it sounds like a better and more responsible conclusion by the authors would have been: it seems theoretically possible that a vegan cat food could exist with correct supplementation, but no healthy vegan diet for cats exists yet (all studies show specific supplementation thus far is neccesarry for existing vegan foods otherwise your cats might very quickly develop major adverse health outcomes—am I wrong?).
They also highlight they didn’t review the suitability of the supplements? What does this mean—“suitability”? Cant find an answer for that.
I could have the official definition wrong—I edited the post. I’m thinking about it colloquially and repudiating how it’s conceived for example here.
I agree that the paper you highlighted is not making its case strong nor clear.
The best evidence seems to be survey based; for example, here: https://faunalytics.org/plant-based-cats-are-healthier-according-to-guardians/
Andrew Knight, a foremost researcher in the area, has a more definitive study publishing this year.
Otherwise, yes, I agree that we must continue to work our way up the Hierarchy of Evidence and campaign for more and better “formal” science.
This is not a semantic issue you can fix with a minor edit. Your post rests on the assertion that cats can be healthy when fed an exclusively plant-based diet, and that these diets are already available. You are sure enough of this to say we should “stridently correct” people who believe they can’t.
You can claim people are wrong to categorize cats as obligate carnivores, but you need to demonstrate that with evidence, which you absolutely have not done. You say the best evidence is survey based, but with such a motivated population and minimal reporting I consider it meaningless.
Even in this comment you act as if the linked reddit comment (copied below) is obviously false, but it is using obligate carnivore correctly and you have provided minimal evidence to even suggest reconsidering that designation.
My steel man here is that it might be possible to render cats vegan with new technology, and you think it’s worth doing. I don’t necessarily disagree with that, but it is such a different claim than “cats are not obligate carnivores and can all happily live on a vegan diet today”.
Reddit comment Karthik links to:
> Hello there. Pet nutritionist here, trust me when I say cats ARE obligate carnivores. If you feed them a vegan diet they WILL die slowly and painfully, no ifs ands or buts. If you cannot cope with the idea of your cat eating what it needs to in order to survive. Give it up
The argument isn’t solely based on the survey data. It’s supported by fundamentals of biochemistry, metabolism, and digestion too. I won’t presume to know your biology knowledge. Earlier, you said “biology as a field is dumb”, which may or may not be indicative of much personal study of biology. So I apologize if this is over-explaining, but I feel that I may have glossed over it when making the post:
Mammals such as cats will digest food matter into constituent molecules. Those molecules are chemically converted to other molecules—collectively, metabolism--, and energy and biomass (muscles, bones) are built from those precursors. For cats to truly be obligate carnivores, there would have to be something exceptional about meat: (A) There would have to be essential molecules—nutrients—that cannot be sourced anywhere else OR (B) the meat would have to be digestible in a way that’s not possible with plant matter.
(A) is very easy to correct for. Just test formulations for missing nutrients (molecules) and add them. So far, there are no “special” meat molecules that can’t be sourced from elsewhere. (B) is making a more digestible formulation. If we extract pea protein and measure the digestibility, we’ll know if it’ll work for a cat or not.
On (A), AAFCO is setting this already with their nutritional guidelines, e.g. minimum amount of proteins, vitamins, etc. On (B), part of the ingredient testing is making sure the food is digestible for cats (also testing for toxicity).
So any plant-based food that passes AAFCO guidelines is nutritionally complete for cats. Ami does, for example.
One of my points is that people’s assumptions about carnivory fail to consider biochemistry. Yes, the formal scientific studies are lacking, but it really shouldn’t matter based on what’s known about more fundamental biology. Do we need long term studies to absolutely know that Yellowclothea people are safe to wear purple?
I agree that more formal studies higher on hierarchy of evidence would convince folks, seemingly like yourself. And to that point, I advocate for more of it. But given what I’ve researched and what I know about biology, I would feel comfortable raising a cat vegan healthily and recommending others to do the same.
I have a BA in biology. “Biology is dumb” was an attempt to be cute about the inherent messiness of living organisms and attempts to classify them.
You say you’ve done research satisfying you that this is all biochemistry and we know everything we need. Can you write that up? How are we sure we’ve identified every useful nutrient? How do we know the bioavailability tests are any good? Without that this is still just an asserton, and a fairly surprising one given the state of human nutrition.
To be clear, this is not what I’m arguing. Biochemistry research is never complete. I’m arguing that it’s safe to feed cats vegan based on what’s known.
Here’s the AAFCO list of required nutrients for cats and what I view as authoritative (pages 13-14):
https://www.aafco.org/wp-content/uploads/2023/01/Model_Bills_and_Regulations_Agenda_Midyear_2015_Final_Attachment_A.__Proposed_revisions_to_AAFCO_Nutrient_Profiles_PFC_Final_070214.pdf
I’m not sure. But these questions persist for Fancy Feast and any other meat cat food as much as they apply to vegan cat food. Are we sure they have every useful nutrient and that the measured bioavailability is good?
Okay, it sounds like your argument is “vegan cat food is capable of meeting the same standard as meat-based food”.
From skimming the AAFCO document it’s not obvious to me AAFCO thinks meeting its standard is sufficient for health (see screenshot below, from page 2). Perhaps there is something I missed, but I have put a lot of time into reading papers I found shoddy and you didn’t find worth defending, so I would like to be sure this why you believe what you believe before investing more time checking it out.
Indeed.
As you pointed out earlier, we don’t know everything that we could know. What do you propose we do? It sounds like your concerns are with food testing for cats period, and they’re not specific to the vegan formulations.
My stance is that if it’s okay to feed cats meat-based food, then it’s fine to feed them vegan food.
Feed animals close to their natural diet while researching how to do better. You dismiss this as “appeal to nature”, but I would describe it as “the burden is on the attempt to change the default”.
> It sounds like your concerns are with food testing for cats period
I assure you I am at least as obnoxious about human nutrition testing, which is better studied and features a more adaptable subject.
“Meeting nutritional requirements” is a far better default standard than what’s “natural”. Few problems with the “natural” standard:
Retail based meat cat food is far from what’s “natural” as I covered in the post.
What’s “natural” isn’t more equivalent to what’s healthy. Is a diseased bird corpse more “natural” than nutritionally-complete vegan cat food? Probably. Healthier? Hmmmm.
“Natural” is imprecise and hard to make actionable. How would an organization like AAFCO put that into words and regulations?
Yep, human nutrition is better studied. There’s more funding and more interest in the subject.
As discussed before, we’re both in agreement for more studies. Funding is needed.
I think when she said “natural diet” she didn’t mean to invoke the naturalistic fallacy.
She meant the diet that we have the most empirical evidence doesn’t harm/kill them. We have some empirical evidence that vegan diets appear to quckly give cats major bad health outcomes without supplementation? The first comment in this thread by Elizabeth pointed this out.
We don’t have empirical evidence of the same happening with meat-based diets. So modern nutritionally complete meat-based diets presently have a 100%-wont-cause-major-adverse-health-outcomes rate. Is this not what the studies seem to show?
No, but consider statistical averages rather than semantic absolutes. If you were to consider all possible meals a cat could reaonably be fed today. On average, it seems reasonable to suspect that they would be healthier if more of those meals were meat-based than plant-based. This is an empirical question, not a semantic one. The nutritionally-complete vegan cat food might be better than the diseased corpose (one single comparison). But having nothing but the nutritionally-complete vegan cat food might be far worse than nothing but meat (statistical average across many samples).
Given how nascent the field is and how we’re only just finding out what supplementation we might have to give cats, it seems like if we were to tell everyone to feed their cat vegan food that we’d probably get a lot of cats with bad health outcomes.
And this would be pretty bad optics-wise for the vegan movement.
Do we have empirical evidence that a specific meat-based food is consistently safe over many years? My understanding is that many change constantly.
Not really. Check out the recall withdrawals over the year: https://www.fda.gov/animal-veterinary/safety-health/recalls-withdrawals
Best we can do is what AAFCO and FDA already do. AAFCO sets nutritional guidelines and ingredient requirements. FDA regulates the safety.
Why is that diet representative of for example nutritionally complete Ami, which has been around for years? Isn’t it much better to just defer to AAFCO’s and FDA’s standards, which Ami meets?
The most parsimonious explanation is that the lack of supplements was the problem, not the “vegan”-ness. If I get sick from my potato chip diet, it doesn’t mean I should avoid a plant-based diet with all required nutrients.
Based on what? I don’t intuit this at all. Furthermore, we’re not saying any plant ingredients. We’re saying the ones that meet nutritional, toxicity, and digestibility requirements for cats.
Both you and Elizabeth have offered something fairly distinct from AAFCO’s/FDA’s standards. And so far, I’m finding neither to be better.
It’s not nascent. AAFCO has been providing guidance on the nutritional requirements for cats for decades.
For me: I agreed with you and felt like my mind was being changed to being pro-vegan-cat—until I read Elizabeth’s comment pointed out the issues in the study. So for me it is mostly because you haven’t engaged with that specific comment and pointed out why the concerns that are highlighted in her screenshots (from the actual study!) are not something that I need to worry about.
Convince Elizabeth and you, by proxy, convince me I’m pretty sure.
Sounds reasonable to me. I didn’t say that a lack of supplementation wouldn’t solve it. I argued that meat would. Arguing for X doesn’t mean I argued for ~Y.
The study came out January of this year. That’s pretty recent.
Does a nutritionally complete vegan cat food exist yet that takes everything learnt from this study and all the studies it references into account without need for additional supplementation? If yes, I’d want to see a study where cats are fed it first before I place my own cats exclusively on it. Till then I’d probably be too paranoid to feed them a fully vegan diet.
I’m confused. By “that diet” you mean to say the diet that was tested in the actual study you use as support for your claims should not be taken as an example of something nutritionally complete?
Ok, after trying to figure out what “Ami” was I see in your post you refer to it as vegan cat food that exists on the market.
Apparently it has also been around for 20 years after a quick Google search. Now I’m just hyper-confused why Ami wasn’t used in the Domínguez-Oliva et al. Study instead.
Thanks Cornelis, I sincerely appreciate the good will shown.
I conceded on Domínguez-Oliva et al., and Elizabeth’s concerns were entirely valid. However, it’s one study and one diet, and I felt that Elizabeth was ignoring the basis of nutrition and biochemistry that I emphasized throughout the post. Thanks for highlighting that the food was lacking necessary, known supplements. That was a key point that would have been helpful to broach earlier.
A RCT study will likely be just a formality for something like the Ami vegan cat food. And yes, it’s frustrating that this hasn’t been done/published yet! As I understand from Andrew Knight, there’s a better study coming out this year.
I haven’t found Elizabeth willing to falsify their thinking as much as you and perceive general antagonism and defensiveness.
Nutrition is hella complicated. As someone who drinks a ton of Soylent, I am often surprised by how my own view of “it shouldn’t matter as long as the molecules—when you break it down—are the same” is overly simplistic. If you have food substance A and food substance B and their molecules are organized differently, then even if you were to break them down and get the same base nutrients, this does not mean they are equally healthy for you. This is because their different initial arrangement can lead to different biochemical cascades. I recently learnt that antimicrobial mouthwash might influence your mouth bacteria to such a degree that is leads to a decrease in NO production to the point that your blood veins don’t dilate as much = causally linked to increased arteriosclerosis. There is an entire scientific journal just dedicated to this pathway. See here.
I would never have intuitively thought this could happen. I can increase my risk of heart disease by nuking the bacteria in my mouth? Lol… wat?
It really is not a stretch to imagine that even if meat and vegan food appears to be nutritionally complete and—if broken down -they yield similar macronutrients—that still because the vegan food has a different composition before being broken down that different biochemical pathways are kicked off leading to harm that the meat-based one does not lead to. Something weird and unexpected like the NO pathway could explain why cats on vegan diets still get health issues as the pro-vegan study Elizabeth linked to shows.
An escape hatch from this would of course be lab grown meat that is to the molecule identical to meat. In that case it wouldn’t make sense for one to be any different from the other because they are not only to the molecule identical, but also to the molecules are arranged the same way before being broken down.
So my read is you haven’t considered option C: There could be an essential arrangement of molecules in meat before they are broken down, that currently cannot be sourced elsewhere (not until we get lab grown meat anyway).
But we have the same uncertainty with retail meat-based cat food, which I’ve highlighted is quite distinct from what cats evolved on.
I don’t understand the obeisance to molecularly-exact meat. Evolution doesn’t select for health and well being. It selects for propagation for a specific niche in a specific environment. Our goals with domestic cats are different than what evolution optimized for.
Consider human evolution. For most of it, life expectancy was far lower than today. The diet of prehistoric times isn’t by default aspirational. Instead, current nutrition studies focus on health outcomes, e.g. life expectancy, blood pressure, rate of obesity, etc.
So recommendations focus directly on cause (food eaten) and effect (health outcomes). And that’s what we should do with cats. We should not put meat on a pedestal and beeline for that.
Actually, I think we don’t have the same uncertainty. Those products have been iterated on for a far longer time than vegan cat food—including multiple FDA recalls as you pointed out. We’ve had much more of a “trial-by-fire” of retail meat-based cat food over a longer period of time.
Though in the other comment you pointed out Ami, which given it has existed for 20 years, I imagine has gone through the same trial-by-fire. A new post that does nothing but focus on the evidence that Ami is fine for your cat would probably convince a ton more people. As I mentioned in my other comment I’m very confused why Ami wasn’t used in the Domínguez-Oliva et al. Study instead.
I’m not interested in molecularly-exact meat. I’m interested in what—via strong empirical evidence—we know wont harm my cat.
Couldn’t agree more, which is why, if we get enough empirical evidence that some particular vegan meal will be ay-ok for cats I’m all aboard.
It is worth adding that I do think we have enough empirical evidence to place dogs on a vegan diet without issue. But my read of the study is we’re not there with cats yet. I really don’t understand why the study authors make the same conclusion for both cats and dogs. The evidence appears to clearly be vastly stronger for dogs than it is for cats.
We should put empirical evidence on a pedestal and while truth-seeking be neutral about whether that includes or excludes meat.
Thanks Cornelis, I agree about the empirical evidence. And indeed, emphasizing Ami and how long it’s been around would have obviated a lot of confusion here.
We seem to disagree about (1) the variance of meat-based retail products versus vegan ones and (2) whether or not the “trial-by-fire” standard is more helpful than just simply the criteria that AAFCO/FDA defines regarding nutritional, toxicity, digestibility, and safety.
(1) Sounds like your priors for the intra-variance of meat-based cat food are lower than the inter-variance between validated meat and vegan cat food. I don’t share these same priors, and the best I can offer is Chapter 6 of After Meat where I explain in detail how I think about nutrition including the fungibility of food. Long story short, I really don’t think there’s anything special nutritionally about meat that can’t be recapitulated elsewhere, but I understand that not everyone has that intuition.
(2) AAFCO updates their standards in light of new evidence. The “trial-by-fire” is baked into their standards. And I suspect if we had similar priors regarding (1), this point may be moot.
But I appreciate your good faith, and I’ll leave it here.