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Jun 9, 2010 12:23 PM

Cooking vegetables: does the nutrition really cook out?

Is it really true that the longer you cook vegetables, the less nutritious they are? I have a friend who is a real health nut. She barely uses any seasonings, oil, etc when cooking. She usually steams her food and eats it totally plain. Even salt and pepper are rarely used. Recently she discovered collard and kale greens. I was telling her how an old boyfriend's mother used to prepare collard greens and how delicious they were, and she went off on this tangent about how there would have been no nutrition left in vegetables prepared the way I was telling her, and that they weren;t even worth eating that way, What is the real truth when it comes to cooking vegetables? I grew up in a household where vegetables were cooked to death and were mushy (second generation Irish American here, so that's how they do it). I prefer my vegetables a bit firm these days. But I'd really like to know if and when greens and other vegetables do lose their nutritional value due to cooking.

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  1. There are basically two types of vitamins- fat-soluble and water- soluble. The water -soluble vitamins are the B-complex vitamins, and Vitamin C. Water soluble vitamins do not stay in the body and must be replenished every day.
    Also, the water soluble vitamins do lose a lot of their nutritionaly value when cooked in water for any length of time. So, for vegetables with water-soluble vitamins (B-complex and C) it is not recommended that they be cooked in water. The best way to prepare these vegetables so as to retain their nutritional value, is to steam them. So, your friend does have a point.
    Hope this helps

      1. re: ipsedixit

        Excellent. Collards and similar greens are typically braised, and the pot likker is consumed greedily by the wise, except by stupid people, including stupid health nuts. (Most health nuts are stupid in an overeducated but underwise way.)

        Mmm. Collards. Mmm.

        1. re: Karl S

          There are few things in life better than pot likker.

          1. re: MandalayVA

            Yes, there are. Pot likker and bacon are divine.

            By the way, is there canned or boxed pot likker?

            1. re: ipsedixit

              If there are, I can't imagine assorted grandmothers would approve.

              My appreciation for collards and likker only comes in the past 3 years. I've lived in the Boston area for over a generation, grew up in the NYC area, and went to college in a part of the upper South where greens were not a big focus of local country cooking that I could see (I never once saw them on a menu, and I also worked in food service for 4 years).

              Now I know better. If only collards weren't so pricey for much of the year. (Not a fan of sharp mustardy type greens, though.)

              1. re: Karl S

                My mom grows collard greens in her garden, as well as kale and Chinese mustard and Chinese chives (and too many things to recount). Everytime she comes over, it's bushels and bushels of these things.

      2. While as a general rule you're going to lose vitamins and minerals in the cooking process, certain fruits and vegetables require cooking to unlock most of their nutritional power for the body to more readily absorb. Tomatoes are a good example. While they lose some Vitamin C, the ability of the body to absorb the lycopene present goes up significantly. Nutrients from raw food is absorbed at a lower rate than cooked foods. So while cooking you lose some of the nutrients, the higher rate of absorption can make up for some of it. Your best bet is to eat a mix of both cooked and raw whenever you can. Variety is key.

        1. Some have mentioned that a combination of raw and cooked veggies are the way to go...a light braise or better yet, steaming, is good for most greens from what I've's more:

          1. Can someone knowledgeable comment on which cooking method is better for retaining nutrients in beans (not green beans obviously but dry beans)? Short blast of high heat (e.g. pressure cooker for beans) or longer and slower (e.g. crock pot)?
            I've not seen any definitive argument one way or other.