Oxalic acid is poisonous? Should I stop eating spinach then? Oh, looks like the article mentions this actually:
> Chard and spinach, in fact, contain even more oxalic acid than rhubarb—respectively, 700 and 600 mg/100 g, as opposed to rhubarb’s restrained 500. Rhubarb’s killer reputation apparently dates to World War I, when rhubarb leaves were recommended on the home front as an alternative food. At least one death was reported in the literature, an event that rhubarb has yet to live down.
> Oxalic acid does its dirty work by binding to calcium ions and yanking them out of circulation. In the worst-case scenario, it removes enough essential calcium from the blood to be lethal; in lesser amounts, it forms insoluble calcium oxalate, which can end up in the kidneys as kidney stones. In general, however, rhubarb leaves don’t pose much of a threat. Since a lethal dose of oxalic acid is somewhere between 15 and 30 grams, you’d have to eat several pounds of rhubarb leaves at a sitting to reach a toxic oxalic acid level, which is a lot more rhubarb leaves than most people care to consume.
That actually sounds like I should be careful with how I consume my spinach (or chard or rhubarb), but more for the sake of kidney stones. I wonder if adding milk or other calcium-rich foods helps?
[one search for calcium-rich foods later]
So spinach is apparently rich in calcium? I'm getting really confused now.
No, spinach is only rich in oxalic acid, not in calcium.
No vegetable is really rich in calcium, which is why it is recommended for vegans to take calcium supplements.
After you ingest oxalic acid, it will find calcium in your body, where it is abundant in blood and in the other extracellular fluids (like sodium and chloride, most calcium stays outside the cells).
Too much oxalic acid will form insoluble precipitates of calcium oxalate, i.e. small stones, which may happen to form in undesirable places, from where they cannot be eliminated.
Most living beings contain calcium, including all plants, but in quantities that are too small for the needs of anyone who has a calcium-based skeleton, unless you eat daily larger quantities of plants than are practical for most humans (e.g. eating between 1 kg and 2 kg of nuts each day, depending on what kind of nuts they are).
Dark leafy greens are not "quality sources of calcium". One would need to eat several kilograms per day. No human does that. The quantity that needs to be eaten is greater than it could seem from the elemental analysis, because a part of the calcium will be lost during cooking and another part will remain bound in insoluble compounds that will not be absorbed in the intestine. Moreover, eating many kilograms per day of dark leafy greens is guaranteed to cause health problems due to oxalic acid and other substances that are present in excess.
All the studies that I have seen have shown that the vegans who do not take calcium supplements have significantly less amounts of calcium in the body than non-vegans and are more prone to osteoporosis.
This kind of false information about plants that are "quality sources" of substances that are really deficient in all plants is very dangerous for vegans. Any vegan must take up to a dozen supplements to maintain optimal health and those who are not aware of this develop sooner or later various health problems and many go back to a traditional diet, without understanding what they did wrong.
I'd encourage you to go to cronometer.com and put in reasonable servings of the food items they listed (not several kilograms of just one food and washing your hands of the conversation) and seeing what nutrients you end up with. You may be surprised.
Add some nut milks in there, too.
> Any vegan must take up to a dozen supplements to maintain optimal health
This is some bottom tier anti-vegan flame bait. Had I seen this sooner, I wouldn't have even responded.
I happen to be a vegan myself, so it is weird to be accused of "anti-vegan flame bait".
Precisely because I am a vegan and I am aware of the difficulties that I had to surpass when switching to a vegan diet and also of the health problems encountered by some relatives who followed a vegan diet, but without adequate supplementation, because they believed the bad advice that is easy to find on the Internet, I felt the need to reply to these comments that perpetuate myths.
Much of the advice for vegans that can be found on the Internet is completely BS, some of which must have been written by false vegans who have never followed their own advice, while the other suggestions must have been written by rich vegans who do not care whether they pay $5 or $50 for a meal, so they believe that e.g. buying plant protein extracts that are 5 times more expensive than animal meat is a rational food choice.
Now I am happy for switching to a vegan diet, but this change took several years, until I have found adequate methods to ensure the correct daily intake for all nutrients, without paying more for food than before and without gaining weight rapidly.
> they believed the bad advice that is easy to find on the Internet
I'm with you 100% on this. But vegans needing a dozen supplements for optimal health is a different claim than bad internet nutrition advice leading people astray from optimal health.
If you personally feel like you need a dozen supplements even as an informed vegan, I would give you some resources or at least refer you to a dietitian.
A controversial point of my own to some people is that vegans should and often must embrace "processed foods" to hit optimal protein goals. Foods like seitan, textured vegetable protein, tofu, and ultra-processed vegan products have the highest protein density. Yet the fear of processed foods is vogue on social media, and there are plenty of green mommy vegan blogs that will list a cup of lentils as a protein heavy-hitter yet never mention TVP, seitan, etc. There is also plenty of other vegan cringe online like the no-oil vegans who minimize dietary fat.
But that wouldn't mean you can't get sufficient protein on a vegan diet.
Social media and Youtube nutrition advice is horrible for everyone, I think. My own father has been convinced that butter is a superfood by Youtube quacks. They also convinced him to quit his blood pressure meds and that the carnivore diet is so healthy that you can dispose of any cautionary blood panel markers—they simply don't apply to you anymore.
If there are no constraints, then it is easy to get sufficient protein on a vegan diet.
On the other hand, with constraints, which in my case were that I was not willing to spend more money for a vegan-based diet than for a meat-based diet, and that I was not willing to spend more than one hour per day with cooking, cumulated for all the meals of a day, while also wanting to eat mostly, if not exclusively, food cooked by myself from raw ingredients, in order to have complete control over the composition of the food, then it becomes difficult to find a solution for adequate sources of vegetable proteins.
At least in Europe, where I live and where tofu and the like are expensive, I could not find a solution within these constraints for a long time.
You have mentioned seitan, which is just another name for gluten protein extracted from wheat floor. This has been the start of my solution, because gluten is the only vegetable protein that can be extracted at home from a cheap food, without any special equipment and without any chemicals except water.
However, while gluten a.k.a. seitan is cheap, extracting pure gluten from wheat dough requires more time and more water than I was willing to spend. The breakthrough happened when I have realized that I do not have to keep washing the dough until all the starch is removed and I obtain seitan. It is enough to wash for a few minutes until I remove about 75% of the starch.
Then I can bake the dough and I obtain a home-made bread that is highly enriched in proteins, with about a 40% to 50% protein content. Now I make every morning for breakfast such a bread from 500 g of wheat floor (much of which is dumped as starch that does not remain in the baked bread), which provides a little more than a half of my daily protein intake. The rest of the proteins come from various vegetables, including enough legumes for an adequate daily intake of lysine.
The number of supplements that a vegan needs to take depend on the cooking methods that are used. For instance I use some cooking methods that remove some undesirable substances from vegetables, but they also remove some of the necessary nutrients, so I add some supplements to compensate for that.
With other cooking methods, the supplements would not be needed, but then the substances that are not removed by cooking could be harmful.
A few other supplements are optional, but without them it is difficult to compose a daily menu with enough of everything, especially when you have a sedentary work so you must eat little to keep your weight. Such optional supplements allow much more varied daily menus.
Besides the supplements mentioned above that can be omitted, there are supplements that are needed by any vegan, because they either do not exist in plants or they exist in a too small quantity and they either cannot be produced by humans or they can be produced only in a too small quantity, so the studies made on vegans have shown that these substances are present in smaller quantities in the bodies of vegans than in those following a traditional diet.
Among this last kind of supplements are: sodium (table salt is the most ancient nutritional supplement, it is strictly needed by vegans, while with enough animal food it may be not necessary) and calcium, iodine and selenium (some plants that are rich in sulfur, like garlic or onion, may contain some selenium because they extract it from the soil together with the sulfur; however this selenium content is unpredictable because it depends on the soil that happened to be used for cultivation; whoever does not own a chemical analysis laboratory cannot count on a known selenium content, so a supplement is necessary), vitamin B12, creatine and choline and taurine, DHA and EPA omega-3 fatty acids, vitamin D3 and vitamin K2 (the humans make vitamin K2 from the vitamin K1 that is found in green leaves, like they also make vitamin A from the carotene found in plants; however while the efficiency of conversion from carotene to vitamin A is known, so e.g. 100 g of carrots per day are certain to provide enough carotene to cover the need for vitamin A, the efficiency of conversion from K1 to K2 is not known and it is not known whether it is possible to eat enough K1 to eliminate the need for an addition of K2; so until further data the prudent choice is to also take K2).
So the above list counts 12 chemical substances that are needed by all vegans, at least until new studies will determine more accurately if they can be substituted in any way. That does not mean that one needs to have in house 12 different supplements, because many of them can be found combined. For instance I use an oil with DHA+EPA and another oil with D3+K2, which I mix in small quantities with the vegetable oil added to food, while the others are either powders that I mix in small quantities with the table salt, or they are taken in a capsule per day (B12, iodine and selenium).
I’m not vegan so it’s none of my business, but: Sure! if you’re not eating processed foods, and you don’t want to spend hours a day cooking, everyone needs supplements.
Don’t forget that our salt and our flour and our milk and — “raw ingredients” — are supplemented by default with micros the standard diet is deficient in.
If the standard diet was vegan, there’d be taurine in the lentils and we’d be saying a meat-and-dairy diet is impossible without “supplements”.
Which kinds of food are supplemented by default varies from country to country.
While table salt is supplemented by default with iodine almost everywhere, flour and milk are supplemented by default only in a few countries and I consider that this is a very good thing and that they should not have been supplemented by default anywhere.
This forced supplementation is stupid, because it will not achieve an appropriate daily intake, except for a few people who happen to eat a certain amount of floor and milk, while for all the others it will be either too much or too little.
The right way to help the poor is to subsidize the price of vitamins and essential minerals, not to waste them by adding them to a certain kind of food, so that everyone who eats something else will not get them.
And the argument that the government should supplement some food ingredients because people have become too stupid to eat what they should, is even more ridiculous. Even supposing that modern people have become more helpless than their ancestors, so they would not be able to identify or catch anything edible when left alone in a forest, that does not mean that they should not be able to at least have the survival skill of buying the right food from a supermarket.
If it is believed that most people are not capable even of doing that, then they should be educated instead of hoping that the solution is that the state should feed them with food ingredients whose composition they no longer understand.
There certainly are few things more important for any human to know, than how to choose what to eat, in order to not die and to remain healthy.
Seems quite complicated. I think you set your protein goals too high if you need to be so careful about what you eat. In general, a diverse enough diet that gives you enough calories also gives you enough protein.
There have been many studies that have discredited the older recommendation of a daily intake of protein around 0.8 g/kg. Their conclusions correspond to a recommendation around 1.1 to 1.2 g/kg.
The majority of the people living in developed countries eat 1.4 g/kg of proteins per day or more.
Eating 1.2 to 1.3 g/kg of proteins per day from a balanced diet restricted to vegetable food to which no special methods for separating the proteins from starch or fat are applied, results in over 3000 kcal per day.
If I eat more than around 1800 to 1900 kcal per day, I gain weight very quickly.
Removing about 75% of the starch from my bread removes at least 1000 kcal per day, which brings the total to less than 2000 kcal.
I have experimented twice with eating only around 0.75 g/kg of proteins per day, and after a few weeks the concentration of albumin in my blood has decreased (low albumin levels in blood can be noticed even without a blood analysis, because they cause swollen feet).
While this was a little lower than the old recommended value, it was close enough that bad effects were not expected. Now I always eat at least 1 g/kg of proteins per day, and up to 1.3 g/kg.
The only parts of plants that have high protein content are the seeds. Excluding soy, the other seeds of legumes have at least a 3 to 4 times higher calorie content than corresponding to the protein content, while most cereals have at least a 6 to 8 times higher calorie content than their protein content.
When someone does heavy physical work, so 3000 kcal per day or more is OK, then yes, a diverse vegan diet without any special cooking methods is good enough.
On the other hand, for a sedentary life it is not possible to reduce the energy intake from vegan food to 2000 kcal/day or less, without some special protein extraction method.
You would have to eat like 5 cups of legumes every day to get enough iron that way if you're a woman. That's almost two pounds. Nuts or greens would be an even higher amount.
Isn't iron in spinach insanely difficult for humans to actually absorb? Quick googling says it's around ~2% of total iron in spinach which we can absorb, so instead of eating 100g to get 2.7g you'd need to eat 5kg of spinach per day.
That might be the recommendation for a very small woman.
For men of average size, the recommended daily intake of iron varies between countries, but it can be as large as 14 mg, which would need at least 400 g of cooked lentils per day, according to your list, which corresponds to lentils cooked with an unknown amount of water, so it is difficult to compare it with lentils cooked in different ways, though it seems that these 100 g of cooked lentils correspond to about 40 g of raw lentils with about 60 g of water.
That's 100g of cooked lentils and 100g of raw spinach. 100g of raw spinach cooks down to about the size of a deck of cards.
Though I don't see the point of quibbling here. My point only gets stronger and stronger as I add in more foods and calories, even packaged grain foods that are incidentally fortified with iron.
Moreover, the lactating dairy cows which are kept in industrial conditions usually receive mineral supplements with calcium and/or phosphorus, in variable quantities, depending on the composition of their food, to achieve a maximal milk production, unlike the cows which graze freely.
Ultrasound breaks them down, a fast non invasive procedure, much like women having an ultrasound scan (and skip over any effect on the foetus). Either way though, you'll end up with shards in your kidneys.
Do you have a source for that? Because while looking up this spinach thing I've come across half a dozen websites, most of them from health institutes that look fairly responsible, stating leafy greens do have calcium. Although in the case of spinach it's barely absorbed, apparently
Having much calcium among vegetables does not mean having enough calcium as a human food.
Your link uses the silly "cup" unit of measure from which it is hard to assess which is the real calcium content.
The right way to show the content of a nutrient in some food is to show how many kilograms or pounds you must eat daily to provide enough of that nutrient.
In the case of calcium the best case that I have seen for various vegetables is that you would need to eat at least 1 kilogram per day, based on the elemental analysis.
However this is far too optimistic, because when cooking the vegetables a part of the calcium may be lost and another part will be bound in insoluble compounds and it will not be absorbed in the intestine after eating.
So a more realistic estimation is that even for the vegetables with the highest content of calcium you might need to eat at least 2 or 3 kg per day.
For nuts and legumes it is impossible to approach even 1 kg of daily intake, as that would include too much energy in starch or fat.
So only leafy vegetables would avoid gaining weight, but eating kilograms per day would be not only unpleasant, but also harmful.
I happen to be a vegan, so I have studied carefully my alternatives and the best for me is to add some calcium phosphate powder to my food, together with the table salt. I use phosphate and not another calcium salt, because even if all seeds and nuts, including all legumes, have large amounts of phosphorus, most of it is contained in phytic acid, which is harmful, so I use preparation methods that remove much of the phytic acid, but they also remove most of the phosphorus, so I compensate that by adding the calcium as calcium phosphate.
Thanks for the information. Upon closer inspection the authors of the link are a nutritionist and an osteopath, so yeah, not quite as reliable as I thought at first.
True, but I prefer to fortify my food myself, because this is not only cheaper but it also allows me to have complete certainty about the composition of the food.
Fortified food is a reasonable solution, which trades off price for convenience, so whether it is chosen or not depends on personal preferences.
There’s not much you can do since adding chalk (which used to be common for both spinach and rhubarb) just creates the oxalate in the pan instead of your body and you can’t remove it. But cooking with lots of water (very short in the case of spinach) and throwing out the water does help to reduce the amount of oxalic acid.
Probably in small doses (like what our ancestors 20000 years ago probably eat when they couldn't find better food) it won't do too much damage.
Cooking will also remove some oxalates.
Overall these are plants defense mechanisms. We know they work well as anti bug measures, ruminants have more complex digestive systems to break them down; it's not always clear what prolonged use on humans will cause.
Carnivores advocate against eating oxalates rich food and when you start a diet with no oxalates you will experience some weird symptoms, you can read about oxalates dumping: https://www.doctorkiltz.com/oxalate-dumping
There are plenty of people with "auto immune incurable" diseases who stopped eating vegetables and were relieved of their symptoms.
I personally started experiencing problems after 10 years of a 95% vegan diet and went carnivore, getting rid of a number of weird health issues I couldn't explain.
> I personally started experiencing problems after 10 years of a 95% vegan diet and went carnivore, getting rid of a number of weird health issues I couldn't explain.
Have you tried just eating many different things in moderation? Fiber has been repeatedly shown to decrease rates of cardiovascular disease, cancer, and all cause mortality. It’s kind of silly to “go carnivore” and use your resulting feelings as a base measurement of success after being vegan. Especially considering many of the benefits of fiber are longer term.
E.g. If you ate a diet of 100% candy bars then switched to vegan or “carnivore”, of course you would “feel better” and your “weird health issues” might go away, but that doesn’t mean either of those diets is the optimal diet for you. They are just better than eating 100% candy bars…
Following an 100% vegan diet in a healthy way requires more care in choosing some appropriate nutritional supplements and in planning what you eat than for any other kind of diet.
I am vegan and I enjoy it, but I would not recommend this for everyone, because there is no doubt that it would be too tedious for most people, who prefer to eat in a more spontaneous way, without needing to ponder whether what they happen to eat has an adequate nutritional content, taking into account what else they had eaten that day.
I'm starting to have some major doubts about how much you've informed yourself on the topic here when you say "carnivore" is more foolproof than a much less restrictive diet like a plant-based diet.
You can see this just by plugging 2000 calories of meat in Cronometer and viewing the nutrition holes. Even 2000 calories of bagels gives you a wider assortment of nutrients than 2000 calories of beef.
This is a popular talking point among carnivore charlatans on social media, but can you show me any meta analysis or randomized controlled trials where they found adverse health effects when humans consume whole plant foods high in oxalates such as leafy greens, beans or whole grains?
I know the charlatans won't. We'll just get petri dish and rat studies but mostly hand-waving narratives.
Though I'm not sure how people find it convincing on a rhetorical level. If these "defense chemicals" are so bad, then over what time period are they supposed to hurt us? 100 years? Because the overwhelming balance of evidence only shows improved health outcomes with the consumption of fruit and vegetables, especially the scary ones like dark leafy greens and legumes.
This just sounds like the "eek, a chemical in my food!" rebranded for the 2020s.
Finally, to circle back to the topic at hand, I just wouldn't center my diet around rhubarb leaves. They're about as enticing as celery leaves.
Yeah oxalic acid plus calcium is calcium oxalate, aka the most common form of kidney stones. Some people also seem to be sensitive to oxalates for whatever reason, and find improvements in health when broadly removing sources from their diets.
The trick is to bind the oxalates before they get absorbed in the body and require removal. So making things like traditional creamed spinach (or other things like turnip or collard greens) removes the potential hazard from chronic intake.
Incidentally the whey portion of dairy also seems to chelate the form of vitamin B12 found in plants, making it much more bioavailable. The casein portion of dairy doesn’t seem to have this same effect.
It’s fascinating to see how the preparation for so many traditional foods basically mitigates the sources of low level toxicity issues while increasing nutrient update, when as a “modern” person I tend to look at it from the perspective of taste.
There are many things which have it, particularly in the wild edible category, and those who have dietary restrictions which limit them to mostly such foods have serious consequences from the presence of it.
The article mentions the content is 500mg of oxalic acid / 100g and says the deadly dose is at 15 - 30g. That makes for 3-6kg of rhubarb leaves. Quite a serving, if you ask me.
In the original British understatement:
> Since a lethal dose of oxalic acid is somewhere between 15 and 30 grams, you’d have to eat several pounds of rhubarb leaves at a sitting to reach a toxic oxalic acid level, which is a lot more rhubarb leaves than most people care to consume.
Treating bees for varroa more takes about 25g of oxalic acid per box of bees. I’d kind of hoped the leaves might have more oxalic, then I could have tried putting rhubarb leaves in there instead of battling fumes, glycerine and strips of paper.
I've lived in fear of rhubarb leaves for 40 years since my Mum warned me about them. We used to grow rhubarb in our garden in England, which I loved, but was terrified of one day being poisoned by the leaves. Took me this long to find out I really didn't have anything to be afraid of, thank you.
This doesn't make sense to me. 200g of cooked rhubarb already has almost 400mg of calcium which is almost half of the 1000mg daily US recommendation and more than half of the 700mg daily UK recommendation.
Thinking dairy is the only source of calcium is meme-nutrition like eating bananas for potassium especially when talking about a food already high in calcium.
Do you know why doesn't the Oxalic acid bind with the calcium of the Rhubarb, and turns into a problem if consumed? Is there enough calcium to bind with the Oxalic acid? Is the calcium in Rhubarb bioavailable?
Genuine questions here, because as I understand, many of the nutricional fact sheets are calculated after the food is broken down and passed though a mass spectrometer.
I'm living in Finland, and that is where I got that knowledge from. So yes, unfortunately my source is also empirical knowledge.
But knowing how certain African cultures learned to neutralize Cassava, and that knowledge passed through generations without knowing the reason why, I learned to not fully dismiss these kinds of knowledge...
Interesting. I'm in New Zealand and hadn't come across this. Being a commonwealth country makes me suspect it's not common knowledge in England either. Or has perhaps as you mention the reasons have been lost over time.
> Why don’t more plants evolve towards the “grass” strategy?
Grasses have a trick: Grass blades grow at the base of the blade and not from elongated stem tips. This low growth point evolved in response to grazing animals and allows grasses to be grazed or mown regularly without severe damage to the plant. https://en.wikipedia.org/wiki/Poaceae#Description
TL;DW the equipment is empty as it is just like a fancy light switch, an ardiuno hack could replace it, it's all the car's job to negotiate the power it needs. The cost is in the installation.
In The vital Question https://en.wikipedia.org/wiki/The_Vital_Question Nick Lane is arguing that the eukaryote symbiotic cell (archea host, bacterial mitochondria symbiot) leads, via sex and the requirement for gene compatibility between the small mitochondrial genome and the host nuclear genome, to a "best fit" pressure on organism with extreme metabolism. Simplified, "Heartbeat hypothesis" (https://en.wikipedia.org/wiki/Rate-of-living_theory) doe snot apply to, say, birds, that have extreme metabolic requirements (= flight). The fact that, among mammals, is bats that fit the same longevity may indicate that the mitochondrial-nucleus gene match idea could be right.
https://www.nationalgeographic.com/culture/article/does-rhub...