Maximizing the Nutritional Power of Produce

Dorian Martin Health Guide

    I’m excited! Today is my first opportunity to snag a share from the produce from the community supported agriculture program. I can’t wait to see what I get! Last week’s stash – which my friend who I’m splitting the share with – included green beans, bok choy, cilantro, carrots, cucumbers, eggplant, green onion, okra, sweet peppers, salad turnips and sweet potato greens. I just received the email about this week’s produce. This week’s stash includes carrots, green beans, cucumbers, eggplant, garlic chives, green onion, okra, habanero peppers, sweet peppers, radishes, turnips and zucchini.

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     This produce is freshly picked and I can smell the earthiness of the various vegetables in the car as I drive the produce bag home. And the taste of freshly picked produce transports me back to summer vacations when I was a girl and we visited my grandparents, who had a garden on the lot next to their home in Independence, MO.


    All of this vegetable love makes me wonder – when are vegetables the healthiest? And when does the nutritional value drop?


    Rice University biologists have found that vegetables and fruits remain alive even after they are harvested. Produce has a circadian rhythm that may affect nutritional value. The circadian rhythms helps the plants defend against insects, especially during daylight when many bugs are active. Plants actually produce chemicals that discourage the plants from eating them. And these chemicals that are designed to ward off bugs can also increase the cancer-fighting properties of some vegetables, such as cabbage.


    In their study, the researchers used cabbage that was purchased from a supermarket. The cabbage leaves were then subjected to changing light conditions. The researchers found that these cabbages leaves continued to adjust the circadian rhythms. Other vegetables that were tested, including sweet potatoes, carrots and leafy greens as well as fruits, also responded to varying levels of light and dark. The researchers found that the amount of chemicals that help fight off bugs – and help humans fight off disease – were elevated during light cycles in these already-harvested vegetables and fruits.


    That tip should help you when you grocery shop (such as picking the vegetables that are near the top or front of the bin where it's the lightest), even if you can’t gauge when the produce was harvested. It’s also important at this point to make sure you look for the hallmarks of the freshest produce.  The University of Tennessee’s Agriculture Extension Service has developed a guide that provides suggestions on how to identify this produce. For instance, apples’ peak season is September through May. The extension publication suggests looking for good color for the type of variety of apple, as well as firmness to touch. In comparison, grapefruit, which are in season between October and June, should be firm, well-rounded, smooth-textured and heavy for the size. You should avoid coarse, puffy and rough-skinned grapefruit. Lettuce, which is available all year, should not be wilted or have bruised areas. Mushrooms, which are coming in season from November through April, should have dry, firm caps and stems. However, small brown spots or open caps still will have good flavor.


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    Another option to boost the nutritional value is eating microgreens. Dr. Michael Greger, a physician and author, points out that microgreens are much more nutritious than mature leaves. “For example, red cabbage microgreens have a 6-fold higher vitamin C concentration than mature red cabbage and 69 times the vitamin K,” he said. Dr. Greger also pointed to research that found that different microgreens provided wide ranging amounts of vitamins and carotenoids. This study found that the microgreens versions of red cabbage, cilantro, garnet amaranth and green daikon radish have the highest concentrations of a variety of nutrients, including ascorbic acids and carotenoids.


    Using these tips, you should be able to begin to make good nutritious choices when picking produce at the farmer's market, in the supermarket, or in your own backyard garden. Enjoy!


    Primary Sources for This Sharepost:


    Berger, E. (2013). Internal clocks of vegetables keep on ticking. Houston Chronicle.


    Greger, M. (2013). Are microgreens healthier?


    The University of Tennessee Agricultural Extension Service. (nd). A guide to buying fresh fruits & vegetables.


    Xiao, Z., et al. (2012). Assessment of vitamin and carotenoid concentrations of emerging food products: edible microgreens.


Published On: October 15, 2013