Then I read that tomato leaves were toxic, so I stopped using them, even though none of us had ever sickened from them. Turns out their toxicity is sort of like the danger of lead poisoning from children's books- an imagined threat rather than substantiated reality.
Harold McGee tried to find out how we know tomato leaves are poisonous, and all he could find was an undocumented claim that tomato leaf tea made children sick- in a book from the 70s, and some anecdotal evidence which was contradicted by applied research. So he tried cooking with the aromatic leaves.
I tried combining finely shredded tomato leaves and just a hint of fish sauce, and found that they made a savory garnish for both rice and pan-cooked halibut. Then I gently fried whole leaves for a few seconds on each side, and they came out crisp and beautifully translucent, delicious sprinkled with a few grains of salt. Dried, they taste like tea. Blanched and puréed, a few spoonfuls of tomato leaf added deep green flavor and color to a pesto. No side effects noted.
Pondering safety while making pesto prompted me to do a background check on basil. It doesn’t contain any alkaloids, but two of the chemical components in its aroma have been found to cause DNA damage and cancer in animals. These substances, estragole and methyleugenol, are also found in other herbs and are added to manufactured foods. A European food safety agency has proposed regulating their use.
There’s no evidence that eating pesto is hazardous. Researchers at Wageningen University in the Netherlands and the Nestlé Research Center in Lausanne, Switzerland, found that an extract of the whole basil leaf can block the DNA damage caused by estragole.
But the ongoing stories of tomato leaves and basil show how little we really know about what we eat. Plant foods contain many thousands of different chemicals, and each one can have a number of different effects on the body, some benign, others not.
Should you use tomato leaves in your cooking? That's your call. Pin It
