We're drowning in neutraceuticals, which are unregulated and often make ridiculous health claims--which is probably the key reason why they've become a $23 billion industry.
The bubbles show a given supplement, and the health benefit in confers. The higher the bubble on the chart, the more evidence there is for its effectiveness. Some supplements appear more than once--for example, omega 3--because they might have multiple effects. And each of those has varying amounts of scientific back-up.