Genetically modified food is food which contains
ingredients that have had their genetic structure modified
in order for them to grow faster, bigger or be more resistant
to pests when growing. Many people are unhappy about genetically
modified foods because they believe they may be harmful to
health and because not enough tests have been done into its
What harmful effects might turn out to be associated
with the use or release of genetically engineered organisms?
This is not an easy question. Being able to
answer it depends on understanding complex biological and
ecological systems. So far, scientists have identified a number
of ways in which genetically engineered organisms could potentially
adversely impact both human health and the environment. Once
the potential harms are identified, the question becomes how
likely are they to occur. Here are the some examples of the
potential adverse effects of genetically engineered organisms
may have on human health. Most of these examples are associated
with the growth and consumption of genetically engineered
[ New Allergens in
the Food Supply ]
Transgenic crops could bring new allergens into
foods that sensitive individuals would not know to avoid.
An example is transferring the gene for one of the many allergenic
proteins found in milk into vegetables like carrots. Mothers
who know to avoid giving their sensitive children milk would
not know to avoid giving them transgenic carrots containing
milk proteins. A study by scientists at the University of
Nebraska shows that soybeans genetically engineered to contain
Brazil-nut proteins cause reactions in individuals allergic
to Brazil nuts.
Genetic engineering routinely moves proteins
into the food supply from organisms that have never been consumed
as foods. Some of those proteins could be food allergens,
since virtually all known food allergens are proteins. Recent
research substantiates concerns about genetic engineering
rendering previously safe foods allergenic.
[ Antibiotic Resistance
Genetic engineering often uses genes for antibiotic
resistance as "selectable markers." Early in the engineering
process, these markers help select cells that have taken up
foreign genes. Although they have no further use, the genes
continue to be expressed in plant tissues. Most genetically
engineered plant foods carry fully functioning antibiotic-resistance
The presence of antibiotic-resistance genes
in foods could have two harmful effects. First, eating these
foods could reduce the effectiveness of antibiotics to fight
disease when these antibiotics are taken with meals. Antibiotic-resistance
genes produce enzymes that can degrade antibiotics. If a tomato
with an antibiotic-resistance gene is eaten at the same time
as an antibiotic, it could destroy the antibiotic in the stomach.
Second, the resistance genes could be transferred
to human or animal pathogens, making them impervious to antibiotics.
If transfer were to occur, it could aggravate the already
serious health problem of antibiotic-resistant disease organisms.
[ Production of New
Many organisms have the ability to produce toxic
substances. For plants, such substances help to defend stationary
organisms from the many predators in their environment. In
some cases, plants contain inactive pathways leading to toxic
substances. Addition of new genetic material through genetic
engineering could reactivate these inactive pathways or otherwise
increase the levels of toxic substances within the plants.
[ Enhancement of the
Environment for Toxic Fungi ]
Although for the most part health risks are
the result of the genetic material newly added to organisms,
it is also possible for the removal of genes and gene products
to cause problems. For example, genetic engineering might
be used to produce decaffeinated coffee beans by deleting
or turning off genes associated with caffeine production.
But caffeine helps protect coffee beans against fungi. Beans
that are unable to produce caffeine might be coated with fungi,
which can produce toxins. Fungal toxins, such as aflatoxin,
are potent human toxins that can remain active through processes
of food preparation.
[ Unknown Harms ]
As with any new technology, the full set of
risks associated with genetic engineering have almost certainly
not been identified. The ability to imagine what might go
wrong with a technology is limited by the currently incomplete
understanding of physiology, genetics, and nutrition.