Snake Oil

The folks at Information is Beautiful have assembled a nice dataset consisting of measurements of the effectiveness and popularity of 129 different dietary supplements.  The graph they produced is appropriately beautiful and interactive, although I don't find it particularly useful for addressing the main question -- is there some relationship between effectiveness and popularity?  That is, are people using the useful supplements or are they just popping snake oil?

I downloaded their data and produced the following scatterplot.  I've highlighted some of the key outliers.

Some interesting lessons: First, the relationship between effectiveness and popularity is positive and statistically significant at the .001 level.  That's encouraging!  But some of the outliers are rather interesting.  Vitamins A and C are apparently way overhyped.  St. John's Wort, which is reputedly useful for mild to moderate depression, is under-utilized, especially when you consider the size of the industry devoted to treating depression.  No one really uses anti-oxidants, and that's a good thing, it seems.  Green tea, folic acid, fish oil, and Vitamin D (my personal supplement of choice) are the real winners here.

(h/t Harris Masket)