[vanderZwan]

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.

[adrian_b]

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.

[cesnja]

You are completely wrong. There are many quality sources of calcium in plants. For example legumes, nuts, seeds, dark leafy greens including spinach.

[adrian_b]

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.

[hombre_fatal]

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.

[adrian_b]

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.

[hombre_fatal]

> 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.

[darkclouds]

> until I have found adequate methods to ensure the correct daily intake for all nutrients,

I use gut feeling, but am mindful of stimulants in the diet, so I mega dose with supplements to get a better idea of what something is doing.

I can highlight the pitfills in the so called double blind placebo gold standard of scientific study on lab animals.

[mminer237]

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.

[hombre_fatal]

They were talking about calcium. But let's plug some iron sources into cronometer:

- 100g lentils: 3.3mg iron, 116cal

- 100g spinach: 2.7mg iron, 23cal

- 100g cooked tofu: 2.7mg iron, 110cal

That's more than 50% of the day's iron recommendation for women in about 250 calories or about 1/8th of the day's calories for the average woman.

[burmanm]

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.

[DropInIn]

The topic every vegan refuses to discuss:

Biolavailability

[adrian_b]

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.

[postmodest]

100g is a large volume of loose spinach and dry lentils. That's a hearty entree for a hungry lass once cooked.

[hombre_fatal]

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.

[mastax]

How does cow's milk contain so much calcium when they only eat plants?

[teruakohatu]

In New Zealand where cows are all grass fed, they eat 50 kg of grass each day. Milk is concentrated nutrients.

[adrian_b]

Correct.

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.

[sva_]

> No vegetable is really rich in calcium, which is why it is recommended for vegans to take calcium supplements

Or just drink German tap water ...

[darkclouds]

> from where they cannot be eliminated.

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.

[vanderZwan]

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

https://www.myfooddata.com/articles/high-calcium-vegetables....

[adrian_b]

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.

[vanderZwan]

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.

[hombre_fatal]

It's often most convenient to incorporate any fortified nut milk into your diet which is what I recommend to most vegans.

My Costco-brand soy milk gives me 60% of the day's calcium and vitamin D in my morning smoothie.

[adrian_b]

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.

[fouc]

do you aim for 500-700 mg/daily?

[mtsr]

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.

[vanderZwan]

> just creates the oxalate in the pan instead of your body and you can’t remove it

If that stops it from being digested and entering my blood stream that would still help though, no?

I'm just confused at how spinach can be both a calcium-rich food and rich in a chemical that extracts calcium from the blood.

[markdown]

Taro leaves (rourou in Fijian) are cooked for a long time (for a vegetable) in order to break down the oxalic acid.

[jokethrowaway]

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.

[elhudy]

> 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…

[adrian_b]

Being “carnivore” is a more foolproof choice.

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.

[hombre_fatal]

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.

[DropInIn]

Animals are intermediaries which process low bioavailability foods and turn into a nutrient highly bioavailable source.

Bioavailability is something vegans practically refuse to acknowledge let alone discuss.

[hombre_fatal]

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.

> Overall these are plants defense mechanisms

This doesn't mean anything. Of the "anti"-nutrients that survive basic cooking, most of them show improved health outcomes in humans: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7600777/

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.

[Modified3019]

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.

[pvaldes]

> Oxalic acid is poisonous?

If you eat too much of it, yes. All Oxalis leaves are edible but only in the correct (small) dose.

[DropInIn]

Don't downplay oxalic acid.

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.

I know first hand it can do serious harm.

Do not downplay it.

[jrmg]

This is still confusing to me. Does it mean that despite the ubiquity of the warnings, I can actually cook and consume rhubarb leaves like spinach?