Garden Myth: Are Green Tomatoes Poisonous?

Standard

Ill.: http://www.pngegg.com & http://www.pngkey.com, montage: laidbackgardener.blog

It’s that time of year again. Nights are getting cold, too cold for your tomatoes to mature on the vine, so you bring them in and put them in a warm spot. Some do continue to ripen, soon turning red, but others remain resolutely green. Can you still eat them?

That’s when you start to hear two different stories. 

“Yes, go ahead and cook them up,” says one side. After all, recipes for green tomatoes abound: chutneys, ketchups, jams, even green tomato bread. And remember the film Fried Green Tomatoes?

“No, don’t!” says another, “They’re poisonous!”

So, what gives? Are green tomatoes toxic or edible? 

The answer to both is … yes! 

Toxic, But Not Deadly

Green tomatoes, one cut open to show the tiny seeds.
Yes, green tomatoes are bit toxic, but not deadly. Photo: http://www.mrswages.com

Most plants contain toxins and that includes your ordinary, everyday vegetables and herbs. People have gotten ill by overeating spinach and carrots, for example. Plants use toxins to protect themselves from predation. But, as omnivores, we humans are pretty good at digesting plant poisons: we can absorb and break down most toxins as long as they’re not too concentrated. So, we can consume a lot of plants and plant-derived foods that other animals (including our dogs, cats and other pets) can’t: onions, coffee, chocolate, walnuts, garlic, etc.

The Toxicity of Tomatoes

Deadly nightshade (Atropa belladonna), purple bell-shaped flower, black berries.
Deadly nightshade (Atropa belladonna) is just one of the many Solanaceae plants considered poisonous. Photo: herbologymanchester.wordpress.com

As for tomatoes (Solanum lycopersicum), they’re in the Solanaceae family, renowned for its poisonous plants: deadly nightshade, mandrake, henbane, datura and more. 

All Solanaceae all contain various toxic alkaloids, of which solanine, atropine and nicotine are the best known. Tomatoes, although they contain a considerable amount of solanine and some atropine, are richest in a less toxic alkaloid called tomatine. 

However, the level of toxic alkaloids is lowest in mature fruits. After all, the plant wants to protect its immature green fruits from predation so they can mature safely and produce viable seeds, so it makes sense green fruits should be toxic, yet mature fruits were designed to be eaten by animals. That’s how fruiting plants reproduce. As the fruit is consumed by a bird, reptile or mammal, its seeds are either dropped on the ground in a new spot or pass intact through the digestive system unharmed, so the animal partner disseminates the seeds far and wide it its feces. 

If tomatoes and other fruits turn bright colors at maturity, it’s an invitation to frugivorous animals: “come and eat me!” the fruit is saying.

As a result, the toxicity of many fruits in the Solanaceae tribe (tomatoes, eggplants, peppers, ground cherries, etc.) drops to nearly zero as they reach maturity. And that’s why most people can eat ripe tomatoes with impunity.

But what about green ones? 

The Green Tomato Situation

Tomato ripening from green to green and red to red.
As tomatoes ripen, they become progressively less toxic… and more and more tasty! Photo: ResearchGate

The closer tomatoes are to ripeness, the less toxic they will be. And the tastier. (Alkaloids are very bitter.) That’s why cooks who know what they’re doing use fairly mature green tomatoes in their recipes: not the hard, dark green balls that are young tomatoes, but full-size fruits starting to turn a paler green, a sign they’re ripening. They’re not as concerned about toxicity (I suspect most cooks don’t even know green tomatoes are somewhat toxic) as about flavor. Those rock hard, very immature tomatoes have a nasty taste and hiding their bitterness takes a lot of inventive food preparation. Also, many recipes that include very immature green tomatoes seriously dilute them with other ingredients. There’s more flour than green tomato in green tomato bread, for example!

Do note that cooking does not destroy alkaloids (it does destroy other toxic compounds), although they do dissolve in water to a certain degree, so if you boil green tomatoes and drain away the cooking water, that would reduce their toxicity. Even so, most green tomato recipes involve them being “cooked in their own juices”: nothing is drained away. Under that circumstance, a cooked green tomato will be just as rich in alkaloids as a raw one.

fried green tomatoes cooking in a pan
The best fried green tomatoes are made from nearly ripe fruit. Photo: http://www.simplyrecipes.com

Still, even hard-as-nails green tomatoes won’t kill you. Their toxicity is quite limited. At worst, if you eat a few, depending on your sensitivity to tomatine and solanine, you may experience a bit of gastrointestinal distress. And indeed, some people seem so highly sensitive to tomato alkaloids, they may not even be able to eat mature tomatoes even though their alkaloid level is very low. So, if green tomatoes make you feel queasy, don’t eat them! 

And don’t eat bowlfuls of green tomatoes, either. That could send you to the hospital. One estimate suggests an average-sized man would have to eat around 300 green tomatoes to reach a lethal dose. But discomfort will set in at much less than that. Moderation in all things is best!

A Few Don’ts

Cartoon of girl feeding a dog a green tomato.
Don’t give green tomatoes to your pet. Ill.: clipartstation.com & http://www.clipartmax.com, montage: laidbackgardener.blog
  • Don’t feed green tomatoes to your pets. Cats and especially dogs are much more sensitive to solanine and tomatine than humans.
  • Don’t eat potato fruits. Potatoes are related to tomatoes and indeed, their fruits look like small green tomatoes, but are much more toxic.
  • Don’t eat green tomatoes in large quantities or if you have a hard time digesting tomatoes.
  • If a green tomato recipe tastes bitter to you, the cook probably used very immature tomatoes that may be fairly rich in toxins, so don’t eat a lot of it.

So, are green tomatoes poisonous? Yes, but only a slightly, not enough to do any harm in most cases. 

4 thoughts on “Garden Myth: Are Green Tomatoes Poisonous?

  1. Dr Gundry says not to eat the tomatoes seeds or skin too! Gastrointestinal distress from tomatoes is why Italians remove the seeds and skins.
    I love fried green tomatoes, but only eat 1 or 2 slices, and now I know why! Thank you! ❤️🦋🌀

  2. JOLJ

    I thought this was well known, we trained young Boyscouts about plants that are toxic.
    As well as the many flowers in the garden that are edible & wild plant that you eat when lost in the forest for days.

  3. Some insist that fried green tomatoes are made from varieties of tomato that are green when ripe, such as ‘Green Zebra’. I sort of suspected that they were made from tomatoes that were not quite so ripe because they were more firm. We do not get many that do not ripen. In fact, there are only a few. They get pickled, and because they are more firm than ripe tomatoes, they pickle reasonably well. One does not eat enough pickles to get sick.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.