WASHINGTON — You might be under the impression that raw vegetables are best for your health, but cooking some veggies boosts what they can do for you.

Cooked white mushrooms have about twice the potassium, niacin, zinc and magnesium as raw mushrooms. Cooking asparagus boosts the level of six different nutrients by more than 16 percent.

An expert explaining all this to Consumer Reports’ ShopSmart magazine details how the cell walls of many vegetables lock in nutrients that heat from cooking can set free to be absorbed by your body. 

To unleash the power of nutrients in carrots, boil them until tender. To get the most out of tomatoes, roast them or simmer on the stove for 30 minutes.  

ShopSmart has special recommendations for getting the most out of spinach. To help your body absorb iron and calcium from the leafy greens, douse fresh spinach in boiling water for one minute. Then, plunge it into ice water for two minutes, drain well, wrap and store it in the fridge.

ShopSmart says spinach prepared that way is great to use in omelets, soup and other dishes.