Garden Myths Vegetables

Garden Myth: Tomato Leaves Are Poisonous

Plant Tomato Leaf Vegetable Tomato Growing Leaf
Common knowledge insists tomato leaves are poisonous, but is it true? Photo: Max Pixel

Well, this is kind of a mix of myth and truth, because tomato leaves can be seen as toxic or nontoxic, depending on your point of view.

Yes, they are toxic because they do contain toxic alkaloids, including tomatine and solanine.

But they’re not toxic enough to poison you unless you consume them in very large quantities. (An adult would have to consume about 1 pound/450 g of tomato leaves to become sick.) Also, the leaves’ unpleasant smell is usually enough to discourage most people from munching on them.

Since they can be safely eaten under most circumstances, some chefs recommend adding one or two tomato leaves to tomato recipes to enhance their “tomato flavor” which can otherwise be diluted by cooking.

Destroyed by Cooking?

20170815B Ildar Sagdejev, WC
Cooking won’t significantly reduce alkaloid levels in tomato leaves. Photo: Ildar Sagdejev, Wikimedia Commons

A few sources I looked at suggested that tomatine and solanine are destroyed by cooking, which would make the leaves safe to eat, but in fact, they are very stable compounds that don’t break down to any great degree when they are heated. On the other hand, they do dissolve in water, so if for some reason you boiled tomato leaves, then drained away the cooking water, that would be a way of reducing any toxicity.

Green Fruits Can Be Poisonous Too

20170815C Hans, pixabay
Immature (green) tomatoes do contain toxic alkaloids, but not enough to be harmful. Photo: Hans, pixabay

Green Fruits Too

20170815C Hans, pixabay
Immature (green) tomatoes do toxic alkaloids and it isn’t wise to consume them. Photo: Hans, pixabay

But surely green (unripe) tomatoes are safe to eat. After all, aren’t they used in cooking?

Well, not really.

Recipes for green tomatoes (fried green tomatoes, tomato chutney, tomato relish, etc.) actually use, rather than hard, marble-sized, highly bitter young tomato fruits, ones that are nearly mature: fully formed, starting to turn pale green rather than the dark green of young fruits, and definitely softer and less bitter.

The level of toxic alkaloids decreases as the fruit ripens and these toxins have already almost completely disappeared when it reaches its final color. So, if the chef knows what he or she is doing, cooked green tomatoes contain few toxins and are safe to eat. But you do have to limit your cooking to nearly ripe tomatoes. If a friend offers you cooked green tomatoes that still taste bitter, a sign that they still contain a lot of toxins, say no!

Can Toxins Be Good for You?

Like many toxins, alkaloids like tomatine and solanine can also be, at the appropriate dose, good for your health. Tomatine, for example, has antibiotic and antifungal properties and it would appear it can even help prevent cancer … but many studies still need to be done before offering tomato leaf pills as a cure-all!

Leaves as Insecticide?

While tomato leaves when used in moderation may be non-toxic to humans, they do appear to be toxic to some insects, especially aphids. In fact, some gardeners produce an insecticidal spray by soaking tomato leaves overnight in water. But what is toxic to insects is not always for humans, so that really proves nothing.

Conclusion

There appears to be no risk in consuming tomato leaves in moderate quantities, so it’s best to conclude that the idea that tomato leaves are toxic is a myth. Just don’t overdo it!Plant Tomato Leaf Vegetable Tomato Growing Leaf

Larry Hodgson is one of Canada’s best-known garden communicators. After studies at the University of Toronto and Laval University where he obtained his B.A. in modern languages in 1978, he succeeded in combining his language skills with his passion for gardening in a novel career as a garden writer and lecturer. He has notably been editor-in-chief of HousePlant Magazine, Fleurs, Plantes et Jardins, À Fleur de Pot and Houseplant Forum magazines and is currently the garden correspondent for Le Soleil and radio garden commentator for CKIA-FM Radio. He is a regular contributor to and horticultural consultant for Fleurs, Plantes, Jardins garden magazine and has written for many other garden publications in both the United States and Canada, including Canadian Gardening, Harrowsmith, Horticulture, Fine Gardening, Rebecca’s Garden and Organic Gardening. He also speaks frequently to horticultural groups throughout Canada and the U.S. His book credits include The Garden Lover’s Guide to Canada, Complete Guide to Houseplants, Making the Most of Shade, Perennials for Every Purpose, Annuals for Every Purpose, and Houseplants for Dummies, as well as nearly 50 other titles in English and French. He can be seen in Quebec on French-language television and was notably a regular collaborator for 7 years on the TV shows Fleurs et Jardins and Salut Bonjour Weekend. He is the President of the Garden Writers Association Foundation and the winner of the prestigious 2006 Garden Media Promoter Award offered by the Perennial Plant Association. An avid proponent of garden tourism, he has lead garden tours throughout Canada and to the gardens of over 30 countries over the last 30 years. He presently resides in Quebec City, Quebec.

5 comments on “Garden Myth: Tomato Leaves Are Poisonous

  1. Pingback: Are tomato leaves poisonous? – Oracle Tutoring, Campbell River, BC

  2. Tomato leaves and stems are toxic, and have been linked to human deaths:

    https://www.sciencedirect.com/science/article/abs/pii/S0011502909000340?via%3Dihub

    Cooking can make them even more dangerous, by concentrating toxic alkaloids in the broth produced by cooking (note the death due to consumption of herbal tea, prepared from tomato leaves).

    Calling this danger a “myth” is irresponsible to the point of criminality.

    • I’ve tried to obtain access to the article mentioned to verify your statement. Unfortunately, the cost (I was told $1,200) is far too much. If you know of any way of obtaining the information you mention free of charge, I’ll gladly rewrite my article.

      • Thank goodness you didn’t even spend $12 to access that article — it actually doesn’t say anything about anyone dying from tomato leaves or stems. In fact, it says the opposite: “there are few data that indicate tomatoes cause toxicity” and “Some communities use tomato leaves as a food source without obvious toxicity.”

      • Thanks for filling me in!

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