nutrient decline in vegetables and fruit (fwd)

[Laura Larsson]

Friends:

Followup from a colleague.

Regards,

Laura Larsson
Health Services, University of Washington
listowner: PHNUTR-L, PHNURSES, PNWHEALTH, PHSW, HSR-L +
http://depts.washington.edu/hserv/hshome.html
http://depts.washington.edu/hsic/hsichome.html

"The illiterate of the 21st century will not be those who cannot read and
write, but those who cannot learn, unlearn, and relearn. "  Alvin Toffler

---------- Forwarded message ----------
Date: Fri, 14 Jan 2000 17:05:58 -0600
From: "Karen Kubena" <k-kubena at tamu.edu>
Subject: RE: nutrient decline in vegetables and fruit


Just a question.

Because of changes in technology, how might variation in levels of nutrients
be associated with increased accuracy of measurement?  An example of
changing methodology involves magnesium.  Prior to the use of atomic
absorption spectrophotometry (AAS), values were quite unreliable.  Some were
higher and others lower than actual levels.

Now that AAS, HPLC and other more sophisticated methods are being used for
several nutrients, the lower levels in new tables might represent actual
nutrient values rather than the nutrient plus "substances that were measured
as the nutrient but were not."

Another example of changing methodology affecting levels of a substance in a
food is the egg.  Cholesterol values of hen eggs decreased a few years ago,
not because the chicken started aerobic exercise, but because the techniques
used to measure the sterol were more specific and did not include similar
molecules that had previously been included in the total.

Best wishes.
Karen
*************************************
Karen S. Kubena, PhD
Professor and
Associate Dean for Academic Affairs
College of Agriculture and Life Sciences
Texas A&M University
College Station, TX 77843-2402
Phone  409/845-3712
FAX    409/845-6083
Email  k-kubena at tamu.edu




> -----Original Message-----

> From: PHNUTR-L-owner at u.washington.edu

> [mailto:PHNUTR-L-owner at u.washington.edu]On Behalf Of abm17 at cornell.edu

> Sent: Friday, January 14, 2000 9:54 AM

> To: Public Health Nutrition Discussion and Information Group

> Subject: RE: nutrient decline in vegetables and fruit

>

>

> Monika

> The samples for the comparisons were taken directly from the government

> published UK food tables, so would represent samples that were purchased

> at the time. The older tables, with data from the 1930s would probably

> have included fruits and vegetables grown with less artificial

> fertilizers than the new tables from the 1980s. However, I have no

> information on

> the farming methods used to grow the vegetables and fruits at either time

> period. Unfortunately this information is not given in the 'Composition

> of Foods' tables. The varieties grown would also be different, again

> there is no information on that.

> I agree that the trend may well be meaningful and it would be extremely

> useful to find out what is happening here.

>  Anne-Marie Mayer

>

> On Fri, 14 Jan 2000 THECOUCH at aol.com wrote:

>

> > Ann,

> >

> > Were the samples taken from a commercial farm, an organic farm,

> both?  I work

> > with eating disorders, one of the few diagnoses in the US that is about

> > nutrient deficiencies.  This trend might be meaningful with regards to

> > rehabilitation with whole foods vs. supplements, and

> maintaining recovery

> > after treatment.

> >

> > Monika M. Woolsey, MS, RD

> > http://www.afterthediet.com

> >

>