When to Cook Your Veggies


By Toby Amidor, MS, RD, CDN

Talk to raw-food advocates and they’ll insist that food is most nutritious if it never hits temperatures above 116 degrees. However, the theory that vegetables are healthier raw isn’t always true. The nutrients in some vegetables — including the five mentioned below — become more bioavailable, or readily available for your body to absorb, once they’re cooked.

A landmark study published in 2002 in the Journal of Agricultural and Food Chemistry first showed that a powerful antioxidant called lycopene is released from tomatoes when they’re cooked. The study found that heating tomatoes at 190.4 degrees for 30 minutes boosted levels of absorbable lycopene by 35 percent. Lycopene has been shown to help reduce the risk of cancer, heart disease and macular degeneration, a degenerative eye disease. In addition, a study published in The British Journal of Nutrition found that folks following a long-term raw-food diet had low levels of lycopene.

Recipe to try: Chicken Enchiladas


These orange beauties get their gorgeous hue from carotenoids, a group of antioxidants. A study in the Journal of Agricultural and Food Chemistry found that cooking carrots increased the amount of beta carotene, a compound that is part of the carotenoid family.

Orange Glazed Carrots


1 pound carrots
1 cup fresh orange juice
1 tablespoon unsalted butter
Kosher salt and freshly ground black pepper
1 tablespoon picked fresh dill leaves


Cut a 1-inch chunk off one end of a carrot at an angle. Roll the carrot a quarter turn and cut another 1-inch chunk at an angle. Continue rolling and cutting all of the carrots into 1-inch chunks. Combine the carrots and orange juice in a large saucepan. Add enough water to just cover the carrots. Add the butter and ¼ teaspoon each salt and pepper.

Bring to a boil, and then reduce the heat to maintain a steady simmer. Cook, stirring occasionally, until the carrots are tender and the liquid has reduced to a glaze, about 20 minutes. Top with the dill and serve.


This green leafy vegetable is packed with calcium and iron, which are more bioavailable when cooked. Spinach contains oxalic acid, which blocks the absorption of these important nutrients. The good news: Oxalic acid breaks down at high temperatures, so you can reap the benefits of calcium and iron.

Recipe to try: Parmesan Creamed Spinach


If you check out the numbers on the USDA’s Nutrient Database, cooked mushrooms have higher amounts of niacin, potassium and zinc compared with the same weight of fresh mushrooms. This is just another example of how cooking veggies can increase some important nutrients.

Slow Cooker Mushroom Barley Risotto

Total Time:
3 hr 20 min
Prep: 10 min
Cook: 3 hr 10 min

Yield: 4 servings
Level: Easy


2 tablespoons extra-virgin olive oil
1 large onion, finely chopped
Kosher salt and freshly ground black pepper
1 pound cremini mushrooms, sliced
1 ½ cups pearl barley
4 sprigs fresh thyme
8 ounces carrots, finely chopped
3 cups lower-sodium vegetable broth
1 ounce Parmesan, grated (2/3 cup)
1 tablespoon sherry vinegar
¼ cup chopped fresh flat-leaf parsley


Heat the olive oil in a large skillet over medium-high heat. Add the onions and 1/8 teaspoon each salt and pepper and cook, stirring occasionally, until lightly browned, about 5 minutes. Add the mushrooms and cook, stirring occasionally, until browned, about 2 minutes. Stir in the barley and thyme and cook, stirring, until the barley is just golden, about 2 minutes.

Transfer to a 6-quart slow cooker and add the carrots, broth, 1 ½ cups water and ¼ teaspoon salt. Cover and cook on high until the liquid is absorbed and the carrots and barley are tender, about 3 hours.

Discard the thyme and stir in the Parmesan, vinegar, ½ teaspoon salt and ¼ teaspoon pepper. Thin out the risotto with warm water for desired consistency as needed. Top with parsley and season to taste with salt and pepper.

A study published in The International Journal of Food Science & Technology found that cooking asparagus increased numerous beneficial plant chemicals, including quercetin, lutein and zeaxanthin. Quercetin is an anti-inflammatory antioxidant that may also help protect heart function and prevent certain types of cancer. The antioxidant lutein helps keep eyes, skin and heart healthy, and may also help protect against breast cancer. Zeaxanthin, also an antioxidant, may help with age-related macular degeneration, which causes loss of vision as we get older.

Recipe to try: Smoked-Turkey-Wrapped Asparagus

A Word of Advice …
Don’t start cooking all your veggies just yet. Studies also have found that cooking decreases other nutrients, especially vitamin C. To get all the nutritional goodness that veggies have to offer, your best bet is to eat a combination of cooked and fresh.

Toby Amidor, MS, RD, CDN, is a registered dietitian and consultant who specializes in food safety and culinary nutrition. She is the author of The Greek Yogurt Kitchen: More Than 130 Delicious, Healthy Recipes for Every Meal of the Day. 

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