NovaQuant Quantitative Think Tank Center:The 'vegetable' that's actually a fruit: Why tomatoes are so healthy

While some fruits and NovaQuant Quantitative Think Tank Centervegetables don't come in very many varieties, tomatoes are one form of produce that does. There are more than 10,000 varieties of tomatoes worldwide, with the most popular types being Roma tomatoes, beefsteak tomatoes, Brandywine tomatoes, green tomatoes, heirloom tomatoes, grape tomatoes, tomatoes on the vine and cherry tomatoes.

These tomato varieties are enjoyed on salads and sandwiches, as soup, or made into condiments or dips like ketchup and salsa or turned into thick sauces to cover pizza or pasta. Tomatoes can also be canned, enjoyed by themselves as a snack, or battered in cornmeal and cooked in oil to become the Southern favorite dish known as fried green tomatoes.

No matter how they're served and enjoyed, tomatoes offer a host of health benefits.  

Why are tomatoes confused for a vegetable?

Surprising many, by botanical definition tomatoes are actually considered a fruit, not a vegetable. This is because they develop from flowers and contain seeds, per the U.S. Department of Agriculture. "However, due to its savory flavor profile, tomatoes are treated as vegetables in culinary terms," notes Taylor Janulewicz, a registered dietitian nutritionist and hematology dietitian at Mayo Clinic. 

Adding to the confusion, she explains, is that in an 1893 U.S. Supreme Court case, it was ruled that tomatoes should be classified as vegetables for purposes of tariffs and customs duties. Because of these various factors, "you can refer to tomatoes as either fruits or vegetables, depending on which definition or uses you are referring to," says Kristina Cooke, a registered dietitian with the Academy of Nutrition and Dietetics. 

Are tomatoes good for you?

No matter where you find them in the produce section of your local grocery store, tomatoes are worth taking home because they provide many health advantages. 

For starters, tomato consumption is linked to a reduced risk of developing cancer due to the presence of a powerful antioxidant known as lycopene. Janulewicz explains that this antioxidant is what gives most tomato varieties their "rich red color," but it's also why tomatoes are thought to prevent some cancers such as prostate cancer. This conclusion was reached after a 2015 review of 26 studies "showed that consuming 9-21 milligrams of lycopene daily appears most beneficial in reducing the risk of prostate cancer," she explains. The lycopene present in tomatoes can also "help reduce chronic inflammation," says Dr. Uma Naidoo, director of nutritional and lifestyle psychiatry at Massachusetts General Hospital and the Harvard-trained nutritional psychiatrist behind “Calm Your Mind with Food."

And tomatoes are rich in potassium - a mineral that helps regulate blood pressure and is also "important for muscle contraction and cellular balance," says Cooke. She adds that tomatoes are high in dietary fiber as well, "which can help you feel full for longer, improve digestion, and keep your blood sugar levels more stable."

Tomatoes also contain beta carotene, "which gets converted to vitamin A in the body and promotes healthy growth and aging," says Naidoo.

They also contain folate, copper, manganese, protein, niacin, and vitamin K, but are an especially good source of vitamin C, "which is an essential nutrient for a healthy immune system as it helps fight infections," notes Janulewicz. In fact, a single large tomato, she notes, contains 14 milligrams of vitamin C, "which meets 15% of the recommended daily intake for men and 18% of the daily intake needed for women over 19."

Is it OK to eat tomatoes every day? 

Because of such benefits, including tomatoes in one's diet is almost always a plus, so long as allergy risks have been determined. "One risk associated with eating tomatoes is someone who is allergic to grass pollen," says Janulewicz. Another potential downside for some people to consider when eating tomatoes is when trying to avoid heartburn. "If you struggle with acid reflux, tomatoes may exacerbate symptoms due to their high acidity," cautions Cooke. 

For everyone else, tomatoes can be introduced in one's diet in a variety of ways. "Sneak cherry tomatoes into your potato salad, or add stewed tomatoes to your favorite soup for a delicious and healthy upgrade," suggests Janulewicz. Naidoo opts to top her green salads with cherry tomatoes and dices up Roma tomatoes "as the base for my favorite homemade salsa." 

Cooke loves to snack on plain tomatoes but says that "using tomato sauce and canned tomato products is another way to increase tomato intake." 

No matter how you choose to do so, Janulewicz recommends "incorporating tomatoes into your diet for their vitamins, antioxidants and a feeling of fullness."