Saturday, March 24, 2007

More Antioxidants in Food

Blackberries rank #1 in antioxidants.Question: Steam either of these foods and you increase their antioxidant content by over 400%.
Hint: They're both vegetables.

Answer: (Select text above line with your mouse.)
Green peppers or Green cabbage

The above might not come as a surprise to those who recall my post Antioxidants in Food, where I discussed a study that found higher levels of antioxidants in a russet potato after it was baked than before. The same was true for cooked tomatoes.

Since I ended my last post advocating food as the preferred source of antioxidants (over supplements), I felt obliged to name some of the best food sources for these compounds.

The most exhaustive analysis of antioxidants in common foods I could find was published in the July 2006 issue of The American Journal of Clinical Nutrition. Researchers analyzed 1113 food samples:

Content Of Redox-Active Compounds (Ie, Antioxidants) In Foods Consumed In The United States

Processing Increases Antioxidant Content of Certain Foods

Before I get to the top 50 antioxidant-rich foods, I want to share an unexpected finding of this study: many foods actually increase their antioxidant content after being cooked.

I compiled the following table from data in the study. It shows 20 foods that have higher antioxidant levels after being cooked compared to before. (Note cabbage and pepper from question above.) Since these numbers are percents, values below 100 represent a loss of antioxidants after cooking. Only 3 foods in this table fell into that category: rice, spaghetti, and corn grits.

Note: I've been getting emails about the pie crust entry in this "Effect of Processing" table. Let me clarify:
  1. This table does not indicate the antioxidant content of foods, only which foods' antioxidant content changes when heated. If you'd like information on the antioxidant content of foods, see the table beneath this one.

  2. In fact, this study's measurement of antioxidants in pie crust is negligible: 0.009 mmol/serving. If the effect of baking increased this amount by, as the table shows, 311% to 1450%, that would still only raise pie crust's antioxidant content to 0.028 mmol to 0.130 mmol/serving. Pie crust is not a good source for antioxidants.

Click for larger.

Top 50

As promised, below is a table of the 50 most antioxidant-rich foods tested in this study, by serving size.*

Click for larger.

* Serving size varies. Below are some that apply to the above table:
  • For fresh fruit, a serving was 1 cup.
  • For walnuts, a serving was 1 oz.
  • For coffee, a serving was 8 oz. brewed.
  • For ground cloves, a serving was 1 teaspoon. (I dare you to consume 1 tsp. ground cloves in a sitting.)
  • For red wine, a serving was 3.5 oz. (That's less than 1/2 cup. Somebody there is a teetotaler.)
  • For fruit juices, a serving was typically 8 oz.
  • For vegetables, a serving was typically 1/2 cup.
Photo by snowcat, from Flicker.

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