Calories in Tomatoes

What makes tomatoes so powerful?

In 1893, the U.S. Supreme Court ruled in Nix v. Hedden that the tomato is legally a vegetable for tariff purposes, despite being botanically a berry. The justices reasoned that people use tomatoes in dinners, not desserts, so common culinary usage trumped botanical science. But the tomato's most surprising property is chemical, not legal. Tomatoes are the richest dietary source of lycopene, a carotenoid pigment linked to cardiovascular health. Counterintuitively, processing tomatoes—cooking them, pureeing them, or canning them—increases lycopene bioavailability rather than destroying it. Heat breaks down the plant cell walls that trap lycopene in chromoplasts, and the thermal isomerization of all-trans lycopene into cis-isomers makes the molecule easier for the human gut to absorb. Adding fat amplifies this further: lycopene is lipophilic, so cooking tomatoes in oil can raise absorption several-fold compared to eating them raw and dry. This is why a tomato sauce simmered in olive oil delivers more usable lycopene than a fresh tomato sliced over a salad. The tomato plant itself belongs to the nightshade family (Solanaceae), making it a close relative of potatoes, eggplants, and bell peppers.