DOCTOR'S DATA INC. STUDY
Organic Foods vs Supermarket Foods: Element levels
By Bob L. Smith
Doctor's Data Inc., PO Box 111, West Chicago,IL 60185
Published in the
JOURNAL OF APPLIED NUTRITION, VOLUME 45, NUMBER 1, 1993
Copyright © International
Academy of Nutrition and Preventive Medicine
ABSTRACT: Organic food has been noted in various studies
as having similar nutritional value as commercial foods. These studies
usually look at the dry ashed concentration and are designed for the
food producer. In this study the average elemental concentration in organic
foods on afresh weight basis was found to be about twice that of commercial
foods.
The difference in nutritional value of organic
foods compared with commercial foods has been studied many times. Sharon
B. Hornick's paper(l) is a well referenced discussion of this question.
The difficulties in controlling soil factors such as available nutrients,
texture, organic matter, and other factors of temperature, light, seed
type, planting and harvesting dates as well as post harvest handling
makes obtaining statistically reproducible studies difficult to impossible.
These studies are intended and needed for the growers but for the consumers
interested in nutrition,what is needed? They go to a store and must
choose between two potatoes or two pears. One is organic, one commercial.
Each is about the same size and looks like the same variety. They need
a simple, practical answer. Do the foods labeled "organic" have
greater nutritive concentration whether from soil factors, use of chemical
fertilizers, harvesting times or from post harvest differences in handling?
One factor, elemental concentration,is reported here from the consumer's
point of view.
Over a period of two years, foods were purchased
at several stores in the western suburbs of Chicago. Apples, pears,
potatoes, and corn were selected, choosing specimens of similar variety
and size. Organic whole-wheat flour and wheat berries were obtained
from catalogs and markets in the Chicago area. Baby foods and "Junior'
foods were also included in the study.
Specimens were taken to Doctor's Data Laboratories,
Inc. in West Chicago,IL for analysis of elemental concentrations. The
method for sample preparation for the analysis of 38 elements is an
open-vessel hot-plate acid digestion. A 0.4 gram specimen of food was
weighed to ± .005 gr. A 1O ml
mixture of ultra-pure nitric acid and perchloric acid in 3 to 2 ratio
is heated with the sample until a clear liquid is obtained. Digested
samples are diluted to a standard volume and analyzed on state-of-the-art
instruments. Comparable specimens were always analyzed sequentially and
often rerun to determine reproducibility of certain elements.
The six tables below provide the results of the testing except for that
of the baby food. (In the studies of the baby food there were minor differences
and these differences were inconsistent.) Graph 6 is a summary of Graphs
1-4. Results are expressed as a comparison of the percentage of organic
foods having more or less of each element as compared with the commercial
foods. This is done to eliminate the influence of the matrix effect on
the results. The matrix effect (caused by different viscosity,acidity
and residue in the ashed specimen), of each food type must be studied
to produce accurate numerical results. In this study, the matrices were
not studied, so numerical results are not reported.
Why so much difference when only minor differences have been noted before?
First, many prior studies compare dry weight values. Nitrogen(2),jibberelic
acid and other substances can increase moisture content of a food.
Second, commercial and organic farming may have changed in the past
few years since many studies have been done.
Thirdly, post harvest handling may make a difference not addressed in
most studies.
Are the levels of elements in food important? The 1988 Surgeon General's
report on nutrition states that nutrition can play a role in the prevention
of such diseases as coronary heart disease, stroke, cancer and diabetes.
Nutritional Influences on Illness(3) cites studies that have found low
levels of elements correlate with many health conditions citing many
studies which show that supplementation of these elements can reduce
symptoms. Examples include: alcoholism, allergy, cancer, candidiasis,
cardiomyopathy, chronic fatigue syndrome, diabetes mellitus, fatigue,
headache, hypertension,obesity, premenstrual syndrome, and rheumatoid
arthritis to name a few. These studies do not directly prove causation
but do document correlations. The elements found to reduce symptoms are
the same elements found in this study at greater concentrations in organic
food.
The study has many limitations, but specimens taken over a two year
period provided quite similar results. Despite the study's rotation,
this suggests there are significant differences between organic and commercial
food. The organic pears, apples, potatoes and wheat had, on an average,over
90% more of the nutritional elements than similar commercial food and
if sweet corn levels are included, Graph 5, the average difference is
over two and one half times.
Limitations include: except for wheat berries,
specimens were obtained only in the western Chicago area; the number
of specimens varied from 4 to 15 per food; only five foods were reported
here; bioavailability of the elements in these foods was not addressed;
purchases were made of foods labeled "organic", and no attempt
was made to verify whether they were correctly described.
This study found for the consumer interested in elemental concentrations,a
significant difference between organic and commercial foods.
Further study would be suggested.
Graphs: 1 & 2 | 3 | 4 | 5 | 6
Graphs 1 and 2 are not so readable but the rest are press on.
References:
1. Hornick. Sharon B. Factors affecting the nutritional
quality of crops. Am. J. Alternative Ag., Vol. 7. Nos. I & 2, 1992.
2. Kumar, Vinod, W.S. Ahlawat, and R.S. Antil. 1985. Interactions nitrogen
and zinc in pearl millet: Effect of nitrogen and zinc levels on dry matter
yield and concentration and uptake of nitrogen and zinc in pearl millet.
Soil Science 139:351-356.
3. Werbach, Melvyn R. Nutritional Influences on Illness, 2nd Ed. 1993,Third
Line Press, Tarzana, CA.
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