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Remember that rhubarb leaves are actually poisonous due to oxalic acid (I've seen quotes of 2-5 kg od leaves being a lethal dose). https://www.nationalgeograph

by rusanu 3y ago

Remember that rhubarb leaves are actually poisonous due to oxalic acid (I've seen quotes of 2-5 kg od leaves being a lethal dose). https://www.nationalgeographic.com/culture/article/does-rhubarb-deserve-its-killer-reputation https://www.nationalgeographic.com/culture/article/does-rhub...

vanderZwan 3y ago
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.
- mtsr 3y ago
  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.
  - markdown 3y ago
    Taro leaves (rourou in Fijian) are cooked for a long time (for a vegetable) in order to break down the oxalic acid.
  - vanderZwan 3y ago
    > 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.
- adrian_b 3y ago
  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 3y ago
    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 3y ago
      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.
- jokethrowaway 3y ago
  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 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 3y ago
    > 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 3y ago
      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.
- pvaldes 3y ago
  > Oxalic acid is poisonous? If you eat too much of it, yes. All Oxalis leaves are edible but only in the correct (small) dose.
- jrmg 3y ago
  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?
- DropInIn 3y ago
  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.
- Modified3019 3y ago
  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.
Xylakant 3y ago
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.
- lostlogin 3y ago
  That’s more oxalic acid than I’d have guessed. 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.
  - progre 3y ago
    Some beekeepers where I live put strips of rhubarb stalks in the hives to treat varoa. Not sure how effevtive it is though.
sergioisidoro 3y ago
That is why so many rhubarb dishes (rhubarb pies, and desserts) are so often served with ice cream and vanilla sauce based on milk products. The calcium in those neutralize any potential issues of the oxalic acid.
- lgsymons 3y ago
  I would be interested to see a source for the claim that milk products are paired with rhubarb for that reason.
  - Illotus 3y ago
    At least in Finland this is common knowledge and pretty much every house has rhubarb growing in the yard somewhere.
    - sergioisidoro 3y ago
      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...
      - lgsymons 3y ago
        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. Thank you for your reply.
- hombre_fatal 3y ago
  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.
qingcharles 3y ago
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.

by rusanu 3y ago

vanderZwan 3y ago

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.

mtsr 3y ago
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.
- markdown 3y ago
  Taro leaves (rourou in Fijian) are cooked for a long time (for a vegetable) in order to break down the oxalic acid.
- vanderZwan 3y ago
  > 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.
adrian_b 3y ago
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 3y ago
  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 3y ago
    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.
jokethrowaway 3y ago
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 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 3y ago
  > 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 3y ago
    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.
pvaldes 3y ago
> Oxalic acid is poisonous? If you eat too much of it, yes. All Oxalis leaves are edible but only in the correct (small) dose.
jrmg 3y ago
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?
DropInIn 3y ago
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.
Modified3019 3y ago
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.

Xylakant 3y ago

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.

lostlogin 3y ago
That’s more oxalic acid than I’d have guessed. 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.
- progre 3y ago
  Some beekeepers where I live put strips of rhubarb stalks in the hives to treat varoa. Not sure how effevtive it is though.

sergioisidoro 3y ago

That is why so many rhubarb dishes (rhubarb pies, and desserts) are so often served with ice cream and vanilla sauce based on milk products. The calcium in those neutralize any potential issues of the oxalic acid.

lgsymons 3y ago
I would be interested to see a source for the claim that milk products are paired with rhubarb for that reason.
- Illotus 3y ago
  At least in Finland this is common knowledge and pretty much every house has rhubarb growing in the yard somewhere.
  - sergioisidoro 3y ago
    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...
    - lgsymons 3y ago
      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. Thank you for your reply.
hombre_fatal 3y ago
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.

qingcharles 3y ago

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.