Microwaving destroys key antioxidant nutrients in fresh vegetables

With the USDA’s recent new recommendations for greatly increased fruit and vegetable consumption, it is a bit surprising that they didn’t also address optimal preparation methods that leave the most nutrients intact. In particular, they might have noted that nutrients are destroyed by microwaving, as referenced below:

Phenolic compound contents in edible parts of broccoli inflorescences after domestic cooking. F. Vallejo, F.A. Tomás-Barberán, C. García-Viguera. Journal of the Science of Food and Agriculture, Volume 83, No. 14, Pages 1511 - 1516, October 2003.

This article was reported on by NewScientist (25 October 2003), with an included graph showing that one important antioxidant nutrient in broccoli, flavonoid, was nearly obliterated by microwave cooking: less than 5% remained in the broccoli, in comparison to steaming which left nearly 90% of this nutrient in the broccoli. (Boiling and pressure-cooking had intermediate results.)

Also as reported in NewScientist, the study authors (García-Viguera, et al.) suspect that the reason microwave cooking is so destructive of antioxidant nutrients is that it produces far higher internal temperatures.

A quick Google search shows that this study has received little, if any, press coverage, and yet, if we are trying to enhance our health through increased vegetable consumption, wouldn’t we want to get all the nutrition possible from the vegetables in our diets? Steaming is quick and easy and produces vegies that taste good, so why wreck them in a microwave?