Are Rhubarb stalks poisonous too ?

I know that you must not eat the leaves.

For the past couple of weeks I've been having stewed rhubarb with double cream for my pudding every evening. It's lovely! But the end of last week I was suddenly unwell, sickness and diarrhea. I'm rarely sick and soon recovered, but laying off the rhubarb just in case. I'm the only one in the family eating it and the only one to get sick, so I'm pretty sure it's the amount of rhubarb I've eaten and not some other bug going around.

Do the stalks also contain the same substance as the leaves but in smaller quantities? Should you only eat the red part of the stalks?

I hate to see it go to waste as there is a ton of it coming in the allotment this year.

 

"The poison in rhubarb
Oxalates are contained in all parts of rhubarb plants, especially in the green leaves. There is some evidence that anthraquinone glycosides are also present and may be partly responsible. It is not clear as to the exact source of poisoning from rhubarb, possibly a result of both compounds. The stalks contain low levels of oxalates, so this does not cause problems.

Chemical Composition of Rhubarb




Water 91.2 - 96.1 %
Solids, total 4.0 - 8.48 %
Solids, soluble 2.1 - 3.0 %
Sugars 0.3 - 2.3 %
Nitrogen, total 0.127 - 0.211 %
Proteins 0.6
Fats traces - 0.7 %
Pectins (Ca-pectate) 0.11 - 0.77 %
Tannins 0.058 - 0.110 %
Fiber, Crude 1.1 - 1.2
Carotenes 1.2 ug/100g
Ash 0.62 - 1.23 %
Acids
Malic 0.73 - 2.15 %
Oxalic acid 0.124 - 1.360 %
Citric acid 0.07 - 0.18 g/100g
Acetic acid 0.02 - 0.16 g/100g
Fumaric acid 0.01 - 0.10 g/100g
Glucolic acid 0.01 g/100ml
Succinic acid 0.02 g/100ml
pH 3.01 - 3.59
Ash constituents
mg/100g
K 212-425
Na 2.2
Ca 44 - 103
Mg 13.6
Fe 0.40 - 0.80
Cu 0.13 - 0.50
P 21.0 - 31.0
S 8.2
Cl 87
Vitamins
A1 30 - 100 I.U.
B1 0.2 ug/100g
B2 0.06 - 0.3 ug/100g
C 7 - 34 mg/100g






During World War I rhubarb leaves were recommended as a substitute for other veggies that the war made unavailable. Apparently there were cases of acute poisoning and even some deaths. Some animals, including goats and swine, have also been poisoned by ingesting the leaves.

The biodynamic (toxicity) mechanism by which oxalic acid works is somewhat different from organic poisons and is more analogous to heavy metal poisoning. Organic poisons often work through at the biochemical level, e.g. cyanide by interfering with respiration at the cellular level, strychnine by screwing up inter-synaptic transmission. There are many molecular substances in foods which offer no nutritional benefit, and must be processed and excreted. Oxalic acid, for example, is excreted in the urine, and its crystals are commonly found in microscopic urinalysis. Too much oxalic acid in the urine will result in kidney or bladder stones. Calcium combines with oxalic acid to form the less soluble salt, calcium oxalate, which is also found in kidney stones. Plant leaves, especially rhubarb, cabbage, spinach, and beet tops, contain oxalic acid. Oxalic acid is also found in potatoes and peas. Vitamin C is metabolized to oxalic acid; it contributes to over-saturation of the urine with crystals and possibly to stone formation."

 

The concentration of oxalic acid is quite low whereas the malic acid is about twice that of oxalic.

Neither should be a problem. Rhubarb contains about the same amount as Brussels sprout and a third as much as spinach.

Apparently bicarb counteracts some of the acidity in the rhubarb but whether it lowers toxicity of oxalic I'm not sure. I eat a lot of it and don't have any stomach problems.

I picked 20lb today (for sale for charity) and shall probably pick another 50lb this week. So I shall almost certainly eat it five times this week (the other times I shall be working my way through the apples in the freezer).

 

That's good to hear, going by what you and others say on here I can rule out Rhubarb as the cause of my one-off sickness bout. I'll try it again next week when my appetite returns.

 

I forgot to add:- apart from @NigelJ 's warning of not to use an aluminium pan (which I heartily endorse) you should try and avoid using copper pans - not that many people have those nowadays.

 

Could it have affected your memory?

 

Never tried them raw before must give it a try.

 

They can be a bit Tart, John,



so you need something sweet, like sugar, honey, maple syrup, to contrast it.......but it is nice!