Tomatoes are known for the earthy, spicy odor of the green foliage that is distinct to the species. People seem divided on whether that scent is pleasant or off-putting.
As it turns out, the pungent aroma is thought to be part of the plant’s defenses against pests and disease. It’s caused by oils stored at the ends of hair-like structures called trichomes on the stems and leaves. You may have noticed this tomato fuzz if you’ve looked closely.
When insects, squirrels, or attentive gardeners disturb the plants, bulbs at the ends of the trichomes are crushed open and release the oils. The volatile chemicals in the oils take to the air, and we smell that recognizable scent.
Though the oils and compounds are meant as a deterrent, tomato leaves are safe for healthy humans to touch and eat. The plant’s association with the nightshade family gave it an unsavory reputation in 1700s Europe and its colonies in America, but evidence suggests it was a victim of circumstance.
Other nightshades, including the more dangerous deadly nightshade, produce a toxic chemical called solanine. Tomatoes were once included among these solanine producers, but leading experts now believe it instead produces a similar chemical called tomatine.
Studies downplay the danger of ingesting tomatine—an adult likely would need to eat at least a pound of tomato leaves to get a dangerous dose—and some suggest it may help lower cholesterol and reduce the risk of some cancers.