You know the mantra: Eat more fruits and vegetables.
Is there more nutritional value when they're cooked or raw? Fresh or frozen? How about canned?
The answer varies, and it depends on many factors. And, considering the big picture, it also may not matter.
Even before they're picked, the same varieties of fruits and vegetables can differ in nutritional makeup depending upon where they are grown – the quality of the soil and other growing conditions.
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Whether or not they're picked at the peak of ripeness, the time in transit from field to store, and the length of time the foods sits on the shelf before you buy and eat it also makes a difference.
To complicate things even further, cooking or processing can have different effects on different nutrients in the same foods.
For example, research suggests that when carrots are cooked, the body has access to more of their health-supporting carotenoids, beneficial chemicals that give carrots their orange color.
At the same time, though, cooking may decrease the amount of polyphenols – another beneficial plant chemical – in carrots.
To maximize the nutritional value of fruits and vegetables:
Buy foods in season and grown locally. They're more likely to have been picked at peak ripeness and less likely to have lost nutritional value in transit to the store or your kitchen. Frozen is as good as fresh.
Conserve nutrients. Use a variety of quick-cooking methods that require minimal added fluids. Steam, sauté, stir-fry or cook in a microwave oven. Cook vegetables until they are tender but not mushy.
Save vitamins and minerals leached into cooking water by using the water to make soup.
Leave the peels on organic produce – cucumbers, carrots, apples – to get the benefits of the added fiber.
Diversify your choices. Fresh and frozen are better than canned, but canned is better than no vegetables at all. Eating a variety of cooked, raw, mashed, whole, fresh, frozen and canned fruits and vegetables can help you get a wide range of nutrients in a number of tasty forms.
The bottom line: Eat more fruits and vegetables. Eating them in different forms can help ensure you get the widest possible range of nutrients.
And if the variety encourages you to eat more of them more often, all the better.