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drdoombot's avatar

Do genetically-modified foods have a negative effect on human health?

Asked by drdoombot (8095 points ) August 31st, 2009

I’ve heard about African nations with food shortages turning down food aid packages that included genetically-modified rice. Cows in the US are fed genetically-modified corn because people don’t want to eat it.

I have to admit, I wonder myself if we know enough about manipulating fruit and vegetable genomes to prevent them from affecting our human physiology. DNA strands and genetic markers work in subtle ways we don’t yet understand; tweaking them might have effects that are not immediately clear.

Is it possible that messing with the DNA of food could have a negative effect on our own DNA? Is there any solid evidence concerning the safety of GM food?

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20 Answers

Qingu's avatar

All foods have been “genetically modified” over history. Before we could raise plants in agriculture, we had to domesticate them from their wild ancestors. (Compare corn to teosinte, its wild ancestor).

Now, most of this has been done simply by selective breeding. Genetic engineering is different because we are actually going into these plants’ DNA and modifying it at that level.

There is no danger that messing with a food’s DNA will negatively affect our own DNA. They aren’t creating glowing mutant crops that will turn you into an octopus.

However, genetic engineering food crops does pose several threats that, while less glamorous, deserve attention (and regulation). For example, a lot of GMO crops are created to be resistant to insects or other pests. But if they become too common, then an insect could develop an immunity. This is the same concern about use of pesticides, and is a natural consequence of any monoculture. Another concern is that GMO crops will interbreed with non-GMO crops in unexpected ways, without human control (such as seeds blowing in the wind). And any crop or food source needs to be tested for human safety.

Facade's avatar

I’m no expert, but I’d say yes.

cwilbur's avatar

Genetic modification in itself is neither good nor bad. It’s the actual modifications themselves that make the difference.

The_Compassionate_Heretic's avatar

Given the choice, I’d rather my food came from as close to the original source as possible with minimal human modifications.
When we start deciding we can make nature better through chemicals or genetic modification, there’s usually undesirable side effects.

dpworkin's avatar

My objection to GMO is not health-related, as Nature and Man have been modifying the genetics of plants for years.

My objection is that huge multinationals like Cargill and ADM have patented genes, and may soon have market-cornering monopolies on certain strains.

Also there is an effect on general diversity – the less diverse the gene-pool, the more subject we are to a single disatster, as in, say the Irish potato famine. Imagine that writ large.

kevbo's avatar

It’s mainly another expression of fascism/imperialism.

The Future of Food

South African GMO crop failure

Although the Starlink debacle certainly doesn’t inspire confidence.

jeffgoldblumsprivatefacilities's avatar

Nope, altered DNA is yummy.

YARNLADY's avatar

I wonder how those who supposedly rejected the food could tell what it was. I have read that it is not labeled.

I was going to point out that humankind would have died out long ago if it was bad, since they have been “modifying” food ever since the ancient times.

drdoombot's avatar

I guess I should have been more precise in my question: I wasn’t referring to selective breeding, grafting and the like. I was specifically referring to laboratory work: genetic modification at the DNA level, etc.

YARNLADY's avatar

@drdoombot To the scientist, there is no appreciable difference.

Shuttle128's avatar

What’s the difference between laboratory genetic modification and selective breeding?

Gah, YARNLADY beat me too it!

Jack79's avatar

Mainly what pdworkin said:

There is no proof that GM food is bad for you. Not even suspicion of that (we’ve been eating GM bananas for almost a century now, none of us grew extra hair, have we? Not to mention a series of products that have been tampered with since ancient times).

However, reducing biodiversity can cause major problems if the preferred strain gets hit (we have seen this happen already with oranges, olives, grapes and other uniform plants). And I also don’t like the taste of all these fake tomatoes that are modified to look red, but not tasty. Or the GM watermelons that are a cross-breed with pumkins and cost a lot less to grow but taste like water. When I was a kid watermelons were dark green (no stripes) and much sweeter.

But it’s all about the money, innit?

YARNLADY's avatar

@Jack79 I’m with you on the taste of grocery store tomatoes. I have noticed the same thing with peaches and other fruits and melons. The mass produced just doesn’t taste good. I grow my own or buy as much as possible at the Farmer’s Market in our near by parking lot.

drdoombot's avatar

I might be gravely mistaken, but I’ve always thought it was like this:

Selective breeding – using nature’s own genetic soup to come up with better plants. It’s still kinda natural.

Laboratory gene-splicing – where a scientist goes, “ooh, let’s try turning this gene off,” resulting in blue tomatoes or zombie epidemics. But seriously, I’ve thought the way this worked was a scientist experimenting with rearranging genes, activating or deactivating genes, or importing genes from other plants. In other words, genetic modifications that cannot occur naturally.

I guess the point I’m getting it is the first method is more like gentle nudging whereas the second is like taking a hatchet to the whole thing.

YARNLADY's avatar

@drdoombot Yes, you and I might see it that way, but to a scientist, both methods are the same.

Shuttle128's avatar

True, the only real difference between natural interspecies breeding and splicing is that you can arrive at a final product that does not, or cannot emerge from nature. This is important though because certain limitations can be overcome. However, doing this can decrease the variability of the species due to overuse of the more successful strain. The United States Department of Agriculture regulates the ways in which splicing is done and tests viability of the species before they are allowed to be sold to the public.

The technical side of what is happening is no different than natural breeding though. New genetic material is being sought after to change the properties of the new species to that of a more desirable nature. There’s as much harm in cross breeding than there is in splicing as far as I know.

BhacSsylan's avatar

@drdoombot You’ve already been answered, but I thought I’d illuminate the subject a bit more. The main difference between the two methods is not what happens, but how quickly it happens. Both methods splice genes between two plants, causing a new modified strain to occur. GM in the laboratory sense is simply faster at this, since scientists are capable of selectively targeting the gene they want, instead of creating many splices and hoping for the right effect. The natural process of mutation and evolution constantly causes genes to be turned on and off in a species, which is easy to see in fast-breeding creatures like the fruit flies used in genetic labs. Saying something like ‘cannot occur naturally’ doesn’t have any real meaning. Genes re-combine into crazy combinations all the time. Again, it’s mostly an issue of the speed at which the changes occur.

For a good example, I point you toward bacteria. Many bacteria, especially the more successful and drug-resistant ones, have machinery explicitly designed for chopping up DNA harvested from other bacterium and splicing it into their own, in case it has a useful effect. This is a completely natural evolution on their part, scientists just happen to use it a lot for experimental work.

Now, to your original question, I’ll just say this: as a biochemist who knows a bit about the subject, in terms of the effect of ingesting GM foods, there is no known or even theorized side effects. The materials used to effect the GM change are never present in further generations of the subject, only the resultant genome, and the DNA injested from these products is harmless. Saying otherwise would be like saying that all the food we ingest could have a chance of suddenly invading our cells and mutating us into, say, wheat people.

Now, the ecological or economic problems with GM crops, that’s a different matter. I’m neither an Ecologist or an Economist, so I won’t even try to touch that.

Darwin's avatar

It’s bad for you only if it is all fried in lard.

mattbrowne's avatar

GMO is like selective breeding in a short time lapse. Time-tested selective breeding gives both the breed and the environment a chance to check out whether they agree with each other.

Cartman's avatar

@BhacSsylan

…Children of the Corn

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