How to cook broccoli for maximum health benefit

Broccoli is considered a nutritional powerhouse, containing many minerals—including potassium, sodium, calcium, magnesium, iron, manganese, zinc, and copper—as well as plenty of vitamin C and disease-fighting compounds. But how does cooking influence its health-promoting properties?

Broccoli is part of the Brassica family of vegetables; other famous members of this group include cauliflower, kale, Brussels sprouts, cabbage, and collard greens. These veggies have received lots of attention for their health benefits, especially for their potential to help prevent cancer.

Polyphenolic compounds in broccoli lend it antioxidant properties, fighting off the effects of free radical damage to cells in the body. It also contains glucosinolates—parents to other substances that may help protect against certain types of cancer. Previous studies have shown that the content of these compounds can vary widely depending on how the broccoli is prepared.

A study published in the Journal of Food Science investigated the effect of stir-frying broccoli with different cooking oils on its nutritional profile. The broccoli was lightly cooked for just over three minutes in each of these oils: refined olive oil, extra virgin olive oil, peanut oil, safflower oil, sunflower oil, and soybean oil. The nutrient content of the cooked broccoli was then compared with that of raw broccoli.

Cooking with different oils didn’t change the mineral content of the broccoli, but vitamin C, polyphenol, and glucosinolate levels were all affected. Peanut oil was the best at preserving broccoli’s polyphenol content; extra virgin olive oil, soy, peanut, and safflower oils were best at maintaining glucosinolate levels; and extra virgin olive oil and sunflower oil were best at maintaining vitamin C content.

The best way to prepare your broccoli

  • Studies have shown that lightly steaming broccoli helps to best preserve its nutritional content.
  • According to George Mateljan, author of The World’s Healthiest Foods, the activity of cancer-fighting glucosinolates can be increased by cutting the broccoli into small pieces, drizzling it with lemon juice, and letting it sit out for five minutes before cooking. This helps activate the enzyme that converts the glucosinolates into their active form.
  • If you are going to stir-fry your broccoli, do so for only three minutes, using either extra virgin olive oil or peanut oil.
  • An alternative to cooked broccoli is to enjoy broccoli sprouts in salads and sandwich wraps. The sprouts contain 20 to 50 times more cancer-fighting compounds than the mature broccoli heads.

“I’ve worried about defeating the health benefits of broccoli by cooking it,” says Erica LePore, a naturopathic doctor and mother of three young children. “It’s great to know that there are some simple things you can do to maximize broccoli’s nutritional content.”

(J Food Sci 2007;72:S064–8)

Kimberly Beauchamp, ND, earned her bachelor’s degree from the University of Rhode Island and her Doctorate of Naturopathic Medicine from Bastyr University in Kenmore, WA. She cofounded South County Naturopaths in Wakefield, RI. Dr. Beauchamp practices as a birth doula and lectures on topics including whole-foods nutrition, detoxification, and women’s health.

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