Re: Is spinach harmful in excess?

In article <[EMAIL PROTECTED]>, Tim Tyler <[EMAIL PROTECTED]> wrote:

> Van Bagnol <[EMAIL PROTECTED]> wrote or quoted:
> 
> > By the way, RDA for iron is 10mg daily (for males - 15 mg for females of 
> > childbearing age), and a half cup of cooked spinach has about 3.2 mg of 
> > iron, so says the charts.
> 
> The iron in spincah is bound up with the oxalate - and is consequently
> not available:
> 
> ``Although spinach contains a lot of iron, it also contains oxalic acid
>   which binds to the iron making it unavailable for absorption. Spinach
>   is still a good source of other nutrients, however.''
> 
>  - http://braindance.com/vegan.htm
> 
> Some think that eating spinach will actually help *reduce* your iron
> levels - since phenolic compounds present in it will inhibit iron
> absorption from a composite meal.

Hmm, that's strange. Another source reports that oxalic acid (and 
Vitamin C) helped _increase_ it:

Reddy NS, Malewar VG. Bio-availability of iron from spinach (Spanicia 
oleracea) cultivated in soil fortified with graded levels of iron. Plant 
Foods Hum Nutr. 1992 Oct;42(4):313-8.

"In vitro availability of iron along with ascorbic acid, oxalic acid and 
phosphorus contents of two varieties of spinach (Pusa Jyoti and 
Allgreen) cultivated in soil with different levels of added iron was 
determined. Addition of graded levels of iron to soil markedly increased 
the total iron and phosphorus contents and significantly decreased the 
bio-availability of iron, ascorbic acid and oxalic acid contents of 
spinach. Ascorbic acid and oxalic acid contents markedly exerted a 
positive influence while phosphorus exerted a negative influence on the 
bio-availability of iron."

<http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&;
list_uids=1438075&dopt=Abstract>

On the other hand, yet another seems to associate reduced oxalic acid 
content and increased Fe availability:

Yadav SK, Sehgal S. Effect of domestic processing and cooking methods on 
total, hcl extractable iron and in vitro availability of iron in spinach 
and amaranth leaves. Nutr Health. 2002;16(2):113-20. 

"Drying and storage had no significant effect on total iron content, 
HCl-extractability and availability (in vitro), while blanching and 
cooking resulted in significant improvement of iron availability, and a 
significant reduction in oxalic acid content, while only blanching 
significantly reduced phytic acid and polyphenol contents. Thus cooking 
and blanching are good ways to improve HCl-extractability and in vitro 
availability of iron."

<http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&;
list_uids=12102364&dopt=Abstract>

Van

-- 
Van Bagnol / v a n at wco dot com / c r l at bagnol dot com
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