Assessment of long-term, multigen feeding studies says GM foods are safe

Jason Major

TechNyou

A review of long-term and multi-generational animal feeding studies declares GM foods are safe, though there are many criticisms of the studies.

The review appears in the journal Food and Chemical Toxicology (in press). They analysed 12 long-term (greater than 90 days) feeding trials and 12 multi-generational feeding trial on a range of GM crops and traits. They analysed these alongside the many 90 day or less feeding studies.

Their overall conclusion is that GM plants are nutritionally equivalent to their non-GM counterparts and can be safely used in food and feed.  The caveat here is that the reviewers had serious concerns with the study design and consequent strength of the statistical analysis for a lot of the studies reviewed. Topping the concern list was the lack of a comparable isogenic lines in the feeding trials. This means that the GM cultivar the researchers used was different to the non-GM one they used as a control. For example, if you go to the nursery to buy sweet corn, you will have loads of different varieties to choose from – all different cultivars. Each of these varieties (or cultivars) will have different nutritional and metabolomic/proteomic, etc profiles and consequently your body will produce different metabolites, etc in response to them. Hence if you have a specific GM cultivar, you should use the same cultivar without the transgenic trait for an accurate comparison.

There were also concerns with many trial having insufficient animals to provide sufficient statistical strength – the more you have the more certain you can be about your results.

Statistics V Biology

One thing that needs to be pointed out is that there is a big difference between something that is statistically significant and something that is biologically significant. In a few of the studies some parameters showed small differences that were statistically significant but not biologically significant. In the case of toxicology, it is the biologically significant that is important. For example, if 10 units of a particular toxin found naturally in a food is declared harmless for humans, and the normal range in a specific cultivar or plant is between 2 and 5 units. If your GM plant is found to have 6 units that may be declared statistically significant, but it is still going to be harmless from a biological perspective so has no biological significance and would be considered safe to eat.

It will be interesting to see if there is any controversy of this review. I have yet to see any which is surprising given the amount of uncertainty regarding the scientific methodology on some of the public papers and the criticism from the review authors. I would have thought this would have provided loads of ammunition for the opposing camps in this debate.  Maybe it is too close to Christmas?