A tomato is 95% water, contains 4% carbohydrates and less than 1% each of fat and protein (table). In a 100 gram amount, raw tomatoes supply 18 calories and are a moderate source of vitamin C (17% of the Daily Value), but otherwise are absent of significant nutrient content (table).
Potential health effects
No conclusive evidence indicates that the lycopene in tomatoes or in supplements affects the onset of cardiovascular diseases or cancer.
In the United States, supposed health benefits of consuming tomatoes, tomato products or lycopene to affect cancer cannot be mentioned on packaged food products without a qualified health claim statement. In a scientific review of potential claims for lycopene favorably affecting DNA, skin exposed to ultraviolet radiation, heart function and vision, the European Food Safety Authority concluded that the evidence for lycopene having any of these effects was inconclusive.
The tomato is native to western South America. Wild versions were small, like cherry tomatoes, and most likely yellow rather than red. The Spanish first introduced tomatoes to Europe, where they became used in Spanish and Italian food. The French and northern Europeans erroneously thought them to be poisonous because they are a member of the deadly nightshade family. This was exacerbated by the interaction of the tomato’s acidic juice with pewter plates. The leaves and immature fruit contains tomatine, which in large quantities would be toxic. However, the ripe fruit contains no tomatine.