ARE ORGANIC VEGETABLES HEALTHIER?
by
JOE SCHWARCZ
___________________
Dr.
Joe
Schwarcz is Director of McGill University’s
Office for Science and Society. He hosts The Dr. Joe Show on
Montreal's CJAD and has appeared hundreds of times on The Discovery
Channel, CTV, CBC, TV Ontario and Global Television. Dr. Schwarcz
also writes a newspaper column entitled The Right Chemistry
and has authored four best-sellers, Radar, Hula Hoops
and Playful Pigs, The Genie in the Bottle, That's
The way The Cookie Crumbles, and Dr. Joe And What You
Didn’t Know.
There
were piles of all sorts of tomatoes in the produce aisle of
the supermarket. But the ones that caught my attention sat neatly
wrapped in plastic in groups of four. They weren’t any
better looking than the others, but their price was a stunning
five dollars and eighty cents! What sort of tomatoes were these
to command a king’s ransom? Well, they were “organic.”
Why did they warrant the investment? Because as the label declared,
“when you purchase organic produce you are taking part
in the healing of our land, the purifying of rivers, lakes and
streams, and the protection of all forms of life from exposure
to chemicals used in conventional farming.” Surely only
a callous chemist with a disregard for nature would purchase
any other sort of tomato.
There
is no doubt that the organic produce market is growing. Some
buy organic because they believe such foods are healthier, others
do so to help save the environment from those nasty agro-chemicals.
These beliefs are certainly worth investigating. But what exactly
does “organic” actually mean? Essentially, organic
food must be produced without the use of synthetic pesticides,
artificial fertilizers, antibiotics or growth promoting hormones.
Genetically modified organisms are not allowed and irradiation
cannot be used to control bacteria. Sounds just like farming
roughly a hundred years ago. Back then feeding the masses required
some 70% of the population to be involved in farming in some
way. Yields were low, crop losses to insects, fungi and weeds
were high. That’s why farmers welcomed the introduction
of scientifically designed fertilizers and pesticides. That’s
why today 2% of the population can feed the other 98%.
Such
advances have not come without a cost. Pesticides and nitrates
from fertilizer enter ground water with potential environmental
and health consequences. So people harken back to the “good
old days,” when food was untainted and people lived in
blissful health. Of course, those “good old days”
only exist in people’s romanticized imagination. Food-borne
diseases were rampant and fresh fruits and vegetables in winter
were virtually unheard of. Nutrient deficiency diseases cut
a wide swath through the population. Of course, not even the
greatest advocates of organic agriculture suggest that we can
realistically turn back the clock and provide food for the world’s
population using only organic methods. They claim a niche market
that caters to people who are conscious of their environment
and health.
So,
do consumers who buy “organic” avoid pesticides?
Hardly. Organic farmers are allowed to use a number of pesticides
as long as they come from a natural source. Pyrethrum, an extract
of chrysanthemum flowers, has long been used to control insects.
The Environmental Protection Agency in the U.S. classifies it
as a likely human carcinogen. There you go then, a “carcinogen”
used on organic produce! Does it matter? Of course not. Just
because huge doses of a chemical, be it natural or synthetic,
cause cancer in test animals, does not mean that trace amounts
in humans do the same. Furthermore, pyrethrum biodegrades quickly
and residues are trivial. But that is the case for most modern
synthetic pesticides as well! And how about rotenone? This compound
was discovered in the 1800s in the extracts of the root of the
derris plant. Primitive tribes had learned that the ground root
spread over water would paralyze fish which then floated to
the surface. Rotenone is highly toxic to humans and causes Parkinson’s
disease in rats. It can be used by organic farmers to control
aphids, thrips, and other insects on fruit. Residues probably
pose little risk to humans, but synthetic pesticides with the
same sort of toxicological profile have been vilified.
Organic
farmers are also free to spray their crops with spores of the
Bacillus thuringiensis (Bt) bacterium which release
an insecticidal protein. Yet, organic agriculture opposes the
use of crops that are genetically modified to produce the same
protein. Isn’t it curious that exposing the crop to the
whole genome of the bacterium is perceived to be safe, whereas
the production of one specific protein is looked at warily?
The truth is that the protein is innocuous to humans, whether
it comes from spores sprayed on an organic crop or from genetically
modified crops. True, organic produce will have lower levels
of pesticide residues but the significance of this is highly
debatable.
A far bigger concern than pesticide residues is bacterial contamination,
especially by potentially lethal E. coli 0157:H7. The source
is manure used as a fertilizer. Composted manure reduces the
risk, but anytime manure is used, as of course is common for
organic produce, there is concern. That’s why produce
should be thoroughly washed, whether conventional or organic.
Insect damage to crops not protected by pesticides often leads
to an invasion by fungi. Some fungi, like fusarium, produce
compounds which are highly toxic. In 2004 two varieties of organic
corn meal had to be withdrawn in Britain because of unacceptable
levels of fumonisin, this natural toxin.
Are
organic foods more nutritious? Maybe, marginally. When they
are not protected by pesticides, crops produce their own chemical
weapons. Some of these, various flavonoids, are antioxidants
which may contribute to human health. Organic pears and peaches
are richer in these compounds and organic tomatoes have more
vitamin C and lycopene. But again, this has little practical
relevance. When subjects consumed organic tomato puree every
day for three weeks, their plasma levels of lycopene and vitamin
C were no different from that seen in subjects consuming conventional
puree. Where organic agriculture comes to the fore is in its
impact on the environment. Soil quality is better, fewer pollutants
are produced and less energy is consumed. But we simply are
not going to feed 7 billion people organically.
Finally,
do organic tomatoes taste better? I can’t tell you. Instead
of shelling out $5.80 for four tomatoes, I bought a bunch of regular
tomatoes, some apples and some oranges for the same total. And
I think I got a lot more flavonoids and vitamins for my money.
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