How poisonous are tomato vines?

December 19, 2007 2:11 PM

I've always thought that tomato vines were quite poisonous, but now I am curious since I've seen one occurrence of someone on TV (celeb chef) cooking with one as flavoring.

When growing up, my mother used to take the stance that the leaves and vine were quite poisonous, to the extent that if she opened a can of tomatoes and there was a leaf in the can, the whole can got tossed. Being a good little scientifically minded kid I did a bit of looking into that one day, and found that yes, there are alkali poisons in a tomato vine, so in my mind, that was good enough for me and it pretty much validated the wisdom of my mother.

Then last night I was watching Heston Blumenthal's show on Food Network where he was trying to make his perfect pizza, and to help flavor the sauce he threw the vine into the sauce for a few hours. He extracted the vine again before preparing the pizza, but based on what I thought I knew about tomatoes and alkali vines, this shocked me. I've done some poking around online but can't seem to get a definitive answer of how poisonous the vine is. Is it "eat an inch and you'll die" class poisonous, or "eat a whole vine and you'll have a tummy upset" class poisonous, or something else entirely.

Because the pizza sauce he made looks very intriguing, and if not for this latent fear of poisoning myself, I'd love to give it a go.

posted by barc0001 to Food & Drink (19 answers total)

This site has them in the "Varied" category, along with spinach and water hemlock. (So, apparently, somewhere between "entirely edible" and "highly toxic.")
posted by fogster at 2:27 PM on December 19, 2007

I can't help on the poison / no pison thing but tomatoes have no real smell. The vines however have that glorious tomato aroma and that's obviously what Heston was after.

His cooking is ridiculously scientific some times so he'll have investigated this fully and used a type or methodology that was completely safe.

His food is also jaw droppingly good.
posted by brautigan at 2:32 PM on December 19, 2007

According to this page it is only toxic if you use large quantities. Still, some people get reactions just touching tomato leaves. I'd leave them out of my sauce.
posted by Alison at 2:37 PM on December 19, 2007

I'd put it in since the people that would die are allergic to tomato anyway.

You should check the sources of your tomato vines though. Stay away from the organic stuff because tomatoes produce these toxins to ward off pests. If you spray the tomatoes with pesticides you can rinse off the poison and there wont be much of it in the vines and leaves because then there is no need for the tomato plants to make poison of their own.

My guess is tomatoes were a lot more poisonous before we started spraying chemicals on them.
posted by uandt at 3:29 PM on December 19, 2007

"there wont be much of it in the vines and leaves because then there is no need for the tomato plants to make poison of their own."

Off topic....... but is that true, or did you make it up? Not to be snarky, I'm curious. Do tomato plants not make natural toxins until something starts eating them?
posted by Ragma at 3:45 PM on December 19, 2007

I'd put it in since the people that would die are allergic to tomato anyway.

Um, what? Toxins and allergens are not the same thing. Tomatine is a glycoalkaloid that irritates the GI tract and affects the nervous system.
posted by oneirodynia at 3:48 PM on December 19, 2007

... in other words, you don't need to be allergic to tomatoes to end up vomiting and convulsing by ingesting a bunch of tomatine. General consensus seems to be that you have to eat quite a bit, since tomatine is present in fried green tomatoes and green tomato pickles, which people eat all the time. I doubt letting the tomatoes sit in a closed container with tomato stems is going to be an issue, however, if you detect any bitterness in the sauce, don't eat it. (I have to say that I'm not sure that any frangrance imported to the tomatoes from the leaves and stem is going to stick around once the sauce is heated. Let me know if I'm wrong about that.)
posted by oneirodynia at 4:00 PM on December 19, 2007

Tomatoes are of the nightshade family, which they share with the famous "deadly nightshade." Their leaves are very, very similar. I've always been advised to stay away from leaves and stalks, but probably some essence is all right.

Sort of like the cyanide in apple seeds...a couple won't hurt ya.
posted by TomMelee at 4:04 PM on December 19, 2007

Uandt, do you have any sources for that? I'd be particularly interested if there are studies on that particular phenomenon.
posted by lilithim at 4:07 PM on December 19, 2007

The leaf that your mother found in the can of tomatoes -- could that possibly have been a basil leaf? Tomatoes (especially italian brands) are often packed with a basil leaf. I don't mean to derail -- I am just hating the thought that a perfectly good can of tomatoes was tossed because of a harmless lil basil sprig.
posted by brain cloud at 4:37 PM on December 19, 2007

Not exactly what you want about edibility of the leaves and vines, but when I grow tomatoes, I should (but don't always) wear gloves and long sleeves to work with the plants. I can't imagine trying to eat the things. Where the vines and leaves touch my skin, it kind of burns and I get a little rash. It doesn't seem to be quite like a normal allergy.

I can eat tomatoes, though.
posted by dilettante at 4:52 PM on December 19, 2007

Our 8 month old grabbed one and ate it while I was picking tomatoes. Poison control said yes, they are poisonous but one was no big deal even for a 8 month old as long as there were no obvious symptoms.
posted by true at 4:58 PM on December 19, 2007

Saw the same Blumenthal show on youtube yesterday. Honestly, I'm in favour of experimentation and all, but the lad obviously never chewed on a tomato leaf as a kid. I remember it's BITTER! (never tried that again, must admit. One time was enough - one leaf won't kill you anyway) Not to mention the glass-like hair covering the vine and leaves... I think I'll stick to basil.

(I tried the reverse-pan + grill cooking method and it works *splendidly*, by the way)
posted by _dario at 5:05 PM on December 19, 2007

It should be noted that nettles are a common ingredient in cheese -
http://www.northumberlandcheese.co.uk/acatalog/copy_of_Nettle.html

Just because something stings or leaves a rash that doesn't mean it's poisonous.
posted by Ragma at 5:11 PM on December 19, 2007

At least according to Harold McGee (On Food and Cooking), the Tomatine is not absorbed and flavoring sauce with a few leaves is fine. As alluded to previously, the reason to do this is to get back the fresh tomato-y aroma that generally gets cooked off from the tomato sauce in its long simmering (so you would add the leaves very close to the end of cooking, as with basil or other fresh herbs).
posted by madmethods at 6:55 PM on December 19, 2007

Thanks for the replies, everyone! And the feedback on the reverse pan cooking method -dario, I will try that as well. I used to work at a pizza restaurant in high school, and found the thought of cooking a pizza in 2 minutes to be mindboggling, but if it works, I'm game!
posted by barc0001 at 8:51 PM on December 19, 2007

Off topic....... but is that true, or did you make it up? Not to be snarky, I'm curious. Do tomato plants not make natural toxins until something starts eating them?

In The Omnivore's Dilemna, Pollan definitely talks about how organic lettuce has stronger natural defenses than conventional over-protected lettuce, and that these chemicals the lettuce produces to protect ourselves are good for us, but the chemical being discussed there wasn't an alkaloid, (if I'm remembering all this right), so tomatoes might be different.
posted by salvia at 9:50 PM on December 19, 2007

And at least if you are a trout tomatine will prevent cancer so my guess is that it is one of those friendly poisons that are good for us in moderation.

Here (pdf) is a pretty good article on how toxic the stuff we eat is. It's just my personal opinion that people eating organic veggies for personal health reasons are being scammed because what they get are just different and more "natural" poisons. I support those eating organic for reasons like sustainability, worker safety and taste though.
posted by uandt at 2:33 AM on December 20, 2007

being a foodie AND italian, I can see how Blumenthal is after the "ur-pizza", and by his process he's after the strongest, richest flavouring possible, both in the dough (adding dry yeast somehow as a flavouring) and in the topping (w/ oven dried tomatoes in addition to a very concentrated tomato sauce, plus the already discussed tomato vine and leaves, I'll pass on that).

Best compromise imho is not to overdo the thing, have a dough with very little yeast and a very long leavening time (standard in Naples is 12 hours, up to 24), b/c due to the very short cooking time (yes, 2 minutes, 4 minutes tops: pizza is traditionally baked in a wood oven heated around 450°C - 840°F ) yeasts are not actually killed during the cooking, so it all can end up to be quite indigestable afterwards (heartburn and all). Such high temperatures make the difference, actually.
posted by _dario at 5:19 AM on December 20, 2007