Hmm. Let me ask you a question. What is really truly safe? The food that we eat are only determined to be safe through the test of time, food that we have eaten over hundreds of years with no mass death.

Even so, it can be dangerous if we eat too much of it. Eg, beer has been around for many years and have been seen to be healthy in some circles, but too much of it can be fatal.

So how do you really know for sure? Would it not be possible that the plant we eat has gone through nature's version of modification known as evolution and has become toxic for consumption?

Figure out what is actually being done. What I found was that a single enzyme found in a closely related species was being imported into this species. It is a more efficient enzyme than a very similar enzyme that is already present. So having this new enzyme (a protein) in the modern cultivated banana pushes the equilibrium slightly towards the manufacture of Vitamin A over its precursor. This might subtly effect the equilibrium metabolism of the plant, but likely no more than a particularly hot or cold day would. Further, the enzyme is only expressed in the fleshy portion of the plant, and so has little bearing the 'plant', only its fruit.

As for the health of the consumer, there is more variation and deviation between two species of banana (of this same kind) than there is between the modified and cultivated varieties. And keep in mind too that the cultivated varieties as we currently eat them are so far removed from their genetic capacity to survive as to actually be sterile.

A single, more efficient protein from a similar species was imported from a non-cultivated species into the more common, sterile, cultivated species to shift the fruit's own biochemical equilibrium along a single metabolic axis towards a few-fold increase in the production of Vitamin A.

On the scale of risk, this one is very near the bottom.

Margarine has a more interesting history than that:

http://en.wikipedia.org/wiki/Margarine#History

It was mostly about making a fat spread that was cheaper than butter. Relatively recent marketing probably made lots of health claims.

I suppose that makes the development a closer parallel with golden rice (or bananas), but I think you are underestimating the understanding that the developers of these organisms have.

Interestingly enough butter consumption has skyrocketed and has surpassed margarine consumption for the first time since the 50s. The hype has worn off, the health benefits haven't been proven, and margarine has become the poster child for "fake" foods.

http://www.businessweek.com/articles/2014-01-30/unilever-add...

It helps that butter tastes so much better. I grew up on margarine and butter was like a forbidden fruit to my mom because it was "so bad for you." I grew up thinking butter was death in stick form. I always bought margarine as an adult because you do what your parents did unless you have a reason not to. Well, at some point a few years ago I questioned it and switched over to butter. Guess who also switched to butter recently after decrying it my whole life? My mom.

The spreads you find in shops in most countries today bear little to no resemblance to margarine. Hence the "modern" health claims.

Is starvation more safe?