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You Ask, I Answer: UV Light’s Effect on Nutrients

800px-apples_supermarketMy science teacher told [my class] that we should never store vegetables in the top shelf of the refrigerator since that exposes them to UV light, which destroys the nutrients.

Is that true?

– Bill (last name withheld)
Tallahassee, FL

Certain nutrients (i.e.: vitamin C and B6) are light-sensitive, which is why vegetables that sit out under harsh UV lights in supermarkets for days on end are often times less nutritious than frozen varieties that are picked and immediately packed.

However, this is completely irrelevant when it comes to refrigerator storage.  Seems to me your teacher forgot that, when a refrigerator door is closed, there is no light inside the actual unit.

The lightbulb only comes on when the door opens to make for easy scouring.

It’s often preferred to store vegetables in crisp drawers, rather than shelves, for better moisture control, not for nutritional purposes.

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6 Comments

  1. kb said on May 29th, 2009

    I actually heard something, I think on NPR last week, that the veggies on the top of the pile grocery stores are actually healthier because the lights promote an increase in some vitamins or maybe anti-oxidants. I just Googled and can’t find anything, but I remember being really surprised that this report said that it’s better to take the veggies that have been on top and exposed to the light.

  2. Andy Bellatti said on May 29th, 2009

    Hmmm… I also tried Googling that, but was unsuccessful. Let me know if you ever find it, as it sounds a little odd to me.

  3. kb said on May 29th, 2009

    Ooh, I found it! The flavonoids in lettuce were found to increase with exposure to LED lights. The radio report definitely overstated these findings :)

    http://www.plantechuk.co.uk/2009/05/19/ultraviolet-light-increases-lettuce-phytonutrients/

  4. dave said on May 29th, 2009

    Ok, now what about food irradiation? :)

  5. Michael Allen said on May 30th, 2009

    While fluorescent lights do emit small amounts of UV radiation, the sun emits much more. This study from the UK Health Protection Agency – http://www.hpa.org.uk/webw/HPAweb&HPAwebStandard/HPAweb_C/1195733790804?p=1158934607746 – indicates that UV exposure from fluorescent lights is about 3% that of natural sunlight. If the nutrition in fruits & vegetables is affected by exposure to UV radiation, isn’t it far more likely that the sun is the cause?

    This article – http://www.startribune.com/lifestyle/homegarden/11311421.html – indicates that 8 hours under fluorescent lights is equivalent to one minute under the noon sun.

  6. Andy Bellatti said on May 30th, 2009

    Michael,

    While true that the sun emits more UV radiation, how often do you see produce left out in the sun for days? In supermarkets, it is not uncommon to have, say, broccoli sit on a shelf for 4 or so days, CONSTANTLY under UV light. Most outdoor markets have produce under some sort of covering so they are in the shade.

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