Broccoli is loaded with vitamins A, C and K, minerals like calcium, potassium and iron, fiber, and a compound tied to potential cancer-fighting effects. But nutrition experts say the way you cook it can make a big difference in how many of those benefits actually make it onto your plate.
According to a recent Washington Post report, boiling broccoli causes water-soluble nutrients to leach out into the cooking water, while high-heat or prolonged cooking methods, including roasting, can weaken its antioxidant, anti-inflammatory and cancer-fighting properties.
“Boiling causes the most loss in nutrients,” said Sol Figueroa, a Florida-based registered dietitian nutritionist with Mochi Health. “Vitamin C and glucoraphanin dissolve in water, so a lot of them end up in the cooking water that gets poured down the drain.”
Glucoraphanin is a natural compound in cruciferous vegetables that converts into sulforaphane during digestion. Sulforaphane has been studied for potential antioxidant and anti-inflammatory effects, along with possible benefits for liver, metabolic and gut health, and cancer prevention.
Simple Ways to Preserve Nutrients
Figueroa recommends using as little water as possible if you do boil broccoli. Sprinkling mustard powder on cooked broccoli can also help, since mustard seeds contain myrosinase, an enzyme that aids the conversion of glucoraphanin to sulforaphane and that can otherwise be lost in cooking.
Prep matters too. “Chopping the broccoli and letting it sit for about 30 to 40 minutes before cooking gives sulforaphane time to form first,” Figueroa said.
She cautioned that much of the research behind broccoli’s health claims comes from lab and animal studies. “We can’t say broccoli prevents disease, but the findings are promising,” she said.
Steaming is considered one of the best cooking methods for preserving broccoli’s enzymes. While steaming usually reduces vitamin C in other vegetables, research suggests broccoli may be an exception, according to the Washington Post. Quickly microwaving broccoli may also help retain nutrients, and saving the cooking water for soup or stew can capture some of the water-soluble vitamins that would otherwise be lost.
Tips From a Chef’s Kitchen
Felice Kaufman, a Florida-based food blogger at Cooking in the Keys and a former chef at Whole Foods Market, said she typically steams broccoli, cutting florets into similar sizes and checking for doneness after about three minutes.
“Taste a piece. If you’d eat it right then, take it out of the pot,” Kaufman said. “The heat keeps cooking the broccoli after it comes out of the pot.”
Kaufman also uses the stalk, trimming and slicing it to cook alongside the florets. “The stalk is the best part,” she said.
She generally prefers steaming over boiling to protect vitamin C, but admits that’s not always practical. “If the sink is full — it happens — I’ll throw the broccoli straight into the boiling water,” she said. “One less thing to wash.”
Despite the differences between cooking methods, both experts agree the most important thing is simply eating broccoli, however you prepare it.
“The most important thing is eating broccoli at all,” Figueroa said, adding that roasting is fine if that’s how your family likes it best.
Kaufman offered similar advice: “Five ounces of broccoli, organic, conventional or frozen, is better than any processed food you can eat.”
