1- L-theanine (or green tea)

They say Japanese Buddhist monks could meditate for hours, both alert and relaxed. One reason may have been an amino acid in their green tea called L-theanine, says Mark Blumenthal, of the American Botanical Council.

Research shows that L-theanine helps curb a rising heart rate and blood pressure, and a few small human studies have found that it reduces anxiety. In one study, anxiety-prone subjects were calmer and more focused during a test if they took 200 milligrams of L-theanine beforehand.