How healthy are tomatoes?

UNITED STATES – Tomatoes have come a long way since the 16th century, when some Europeans called them “poison apples” because they were mistakenly believed to be toxic.

Now, they are the second-most consumed vegetable in the US – behind only potatoes – and recognised for a range of health benefits.

Here is what nutrition experts say about tomatoes.

They are hydrating

Tomatoes are 95 per cent water. One cup of chopped raw tomatoes has about 180ml of water, making them even more hydrating than watermelon.

Fresh, raw tomatoes have the highest water content, said Emeritus Professor John Erdman of nutrition and food science at the University of Illinois Urbana-Champaign. When they are cooked, they tend to lose a bit.

Lycopene may help protect against cancer

Tomatoes pack a hefty dose of the antioxidant lycopene, whether they are raw, cooked or sun-dried. Tomatoes and tomato products – ketchup, spaghetti sauce and juice – provide more than 80 per cent of the lycopene in the US diet, Prof Erdman said.

Antioxidants like lycopene can help counteract oxidative stress in the body, he said. Over time, that stress can cause chronic inflammation which, in turn, can increase the risk for many types of cancers.

Scientists have not definitively found that eating foods high in lycopene – or any antioxidant, for that matter – can directly stave off cancer, said Associate Professor Rachel Kopec of human nutrition at Ohio State University.

But human and animal studies – some using tomatoes, some using other sources of lycopene like supplements – have suggested links between high lycopene levels and lower risk of prostate and lung cancers, among others.

Some studies have also suggested that lycopene could help prevent heart disease, liver disease and other chronic health conditions. But researchers have not proven cause and effect here either, Prof Kopec said.

The redder the tomato, the higher the lycopene level, Prof Erdman said.

Orange and yellow tomatoes have a different type of lycopene that presumably has similar health benefits, but researchers have not studied it enough to know for sure. Green tomatoes do not contain lycopene.

Cooked tomatoes contain more lycopene than raw ones, added Professor Alice H. Lichtenstein of nutrition science and policy at Tufts University. That is because cooked tomatoes become more concentrated when they lose some water.

One cup of cooked tomatoes has about 7,300 micrograms of lycopene, as opposed to about 4,600 micrograms in raw tomatoes. What is more, Prof Lichtenstein said, the heat involved in cooking tomatoes breaks down their cell walls, making the lycopene more accessible.

And because lycopene is fat-soluble, eating tomatoes with a bit of healthy fat can help your body absorb the lycopene, Prof Kopec said. She recommended drizzling tomatoes with olive oil, or pairing them with avocado.

Abundant in vitamins and minerals

Tomatoes are a good source of potassium, said dietitian Pinkin Panchal and assistant teaching professor of nutritional sciences at Rutgers University. One large, raw tomato has 431mg of potassium, about as much as a medium-sized banana.

She also noted that tomatoes have decent amounts of folate, a vitamin that helps your cells divide – especially important during pregnancy – and vitamin K, which helps with blood clotting and bone health.

How to enjoy them

Fresh tomatoes are most nutritious when they are picked off the vine at peak ripeness, so buying them locally and in season is best.

All the experts said while it is not necessary to buy organic, rinsing raw tomatoes before eating them can help to remove any lingering pesticides or residue. NYTIMES