In Carlene Thomas’ experience, two types of people ask her advice as a dietitian about the healthiest way to prepare vegetables.Those looking to improve their diet are curious about how different cooking methods affect nutritional content.Others wonder how best to work more vegetables into their diet in general.The simplest version of her answer to both groups is: The best vegetables are the ones you actually want to eat.“A lot of people engage in aspirational vegetable shopping” without actually using them, said Thomas, of Leesburg, Virginia.
In that case, “It doesn’t matter how you cook them, because if they’re going in the trash, they’re not in your body.”That said, research shows different cooking methods do affect the nutritional content of produce, but it’s not as simple as raw vs.steamed vs.
roasted.Not always.Prolonged exposure to high heat degrades many nutrients.
But cooking not only softens the cellular walls in vegetables, making them easier to digest, it also changes their structure to increase what’s called bioavailability — the body’s ability to absorb the vegetables’ nutrients, Thomas said.The result is often more nutritious than raw food.Cooked tomatoes, for instance, release more of the cancer-fighting antioxidant lycopene than raw, she said, and cooked carrots have more betacarotene that can be absorbed. Roasting pumpkins, carrots and sweet potatoes boost carotenoids, the rich pigments that are antioxidants known to combat inflammation in the body.Generally, the shorter the cooking time, the more nutrients are preserved.
Partly because they take relatively little time, steaming and microwaving are considered the most nutritious methods (also because they require no fat to cook), said Amber Pankonin, a dietitian in Lincoln, Nebraska.A close second is blanching — tossing vegetables into boiling water for a minute or two — but be careful not to leave them in the water long.Boiling vegetables, besides easily tu...