Are You Sure This Is the Analogy You Want?

Some of the commenters on an Instapundit post on the GMO controversy are comparing it to the global warming and cholesterol controversies. The odd thing is that these people are critical about the claims that both Anthropogenic Global Warming and saturated fat are dangers but they regard GMO foods as a danger. The reasoning appears to be as follows: If the fear mongers were wrong about X and wrong about Y, they must be right about Z. Is it their turn to be right?