Alan Levinovitz has a great article in Slate about scientific claims on food, which he argues are both misleading us and making us dumber. You should read the whole thing, not least because he (perhaps with tongue in cheek?) calls 43(b)log “the Web’s best false advertising blog.” Excerpt:
Regulating this kind of deception is difficult in America for a variety of reasons. First, there’s a peculiar bipartisan skepticism that frames scientists as minions of either big government or big business, depending on one’s political leaning. The FDA is either a liberal cabal out to destroy capitalism and dictate public access to medicine, or it is a pawn of Big Pharma, a corporate arch-villain bent on keeping us from knowledge of Mother Nature’s secret blessings…
Unfortunately, belief in the power of disclaimers is as unscientific as belief in the power of vitamin C. We know this because the FDA’s very own scientific studies prove it! When examining the effect of qualified health claims, investigators reported that FDA qualified health claims at Levels 2 and 3 were actually “more positive with a disclaimer than without.” For health claims in general, “the disclaimer being there made no difference.” And as for claims like Coca-Cola’s may help shield the omega-3s in the brain? “We got what we sometimes refer to as a boomerang effect where people were more negative when they saw a claim that didn’t have the ‘may’ there.”
In other words, disclaimers don’t work, and qualifications might actually make unfounded claims sound even stronger. (Notice the “might” in that last sentence. Did it work?) Not very encouraging, and not something people want to believe.