North American Fruit Explorers mailing list at ibiblio

["Stephen Sadler" <Docshiva@Docshiva.org>]

The paradox stated at the start of that article is correct, but the
conclusion, though possible, is not definitive.  There are other
explanations, such as catalysis in the liver, that could explain why apples
increase antioxidant action in the blood at a greater degree than would be
expected by their apparent serum metabolites.  

It's happened several times in nutrition that we think food compounds are
poorly absorbed but find that the actions that those compounds would have
caused still occur.  This is exactly the paradox here.  In the past there
has been an underestimation of the complexity of absorption and conversion
of those food compounds.  

You just can't adequately measure uptake (and utility) of many food-borne
compounds by measuring serum metabolites, although the method certainly
works for, say, testing for certain drugs or chemicals.  

What would work is seeing what's left over - in this case the amount of
flavonoids - in the portion of the animal's waste directly attributable to
the apple.  Another thing that works is looking at the resultant antioxidant
effect then backing up the chemistry, reaction by reaction, to the source.  

BTW, this study doesn't mean you need to switch to Red Delicious.  Red
apples would generally have more action than green, and cider apples
probably more than eating apples (but no so much the cider - you need to eat
the fruit).  

Stephen Sadler, Ph.D.
USDA 9, AHS heat zone 8, 
Sacramento CA - Mediterranean climate


-----Original Message-----
From: nafex-bounces@lists.ibiblio.org
[mailto:nafex-bounces@lists.ibiblio.org] On Behalf Of Mark Lee
Sent: Monday, June 20, 2005 12:39 PM
To: 'North American Fruit Explorers'
Subject: [NAFEX] why apples are healthful

http://lpi.oregonstate.edu/fw04/apples.html

The link above will take you to a discussion about why apples are
healthful.  It is a simplified version of a study published last year in
the journal called Free Radical Biology and Medicine (Lotito, S.B., and
Frei, B. (2004) The increase in human plasma antioxidant capacity
following apple consumption is due to the metabolic effect of fructose
on urate, not apple-derived antioxidant flavonoids. Free Rad. Biol. Med.
37, 251-258).

The conclusion of the study is that apples are healthful because of the
fructose they contain.  The antioxidant flavonoids are getting in the
news lately, but this study found that this substance is not making its
way into the bloodstream.  If this study is true, it would make much of
the effort to promote flavonoid-rich fruits seem like a waste of money.
It also would mean fructose is not the evil substance that nutrition
experts are making it out to be.

I have contacted both authors on the paper and some others involved in
flavonoid research, and asked for comments on the study.  I haven't
received any replies yet.  Are there any fruit explorers out their doing
nutrition research in their day job that can comment on this paper?

Thanks,
Mark Lee

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