[pishpash]

This sounds like something that should be followed up with placebo experiments.

[dmitryminkovsky]

For sure, but how would that be possible with NIH human experimentation guidelines?

[srtjstjsj]

Take a bunch of people and remove annatto from the diet of half of them. For the annatto foods or their placebo substitutes, grind up and dye the food so the eater can't distinguish from placebo.