A Japanese group, led by Kozo Hayaski of the Tokyo University of Education, isolated
blue crystals from flower petals of the spiderwort (Commelina communis) and proposed that the crystals were composed of two
pigment molecules, one of which was an anthocyanin and the other a flavone — a yellow
pigment — joined to a magnesium metal ion.
If you go for red cabbage, you'll also get a healthy dose of anthocyanins (the same
pigment molecules that make blueberries
blue), another powerful antioxidant with an anticancer punch.