It is not a new finding that exposures to stress can reduce a person's ability to remember and recall. This has been known for some time. Recent research now shows that theanine, a.k.a. gamma-glutamylethylamide or 5-N-ethyl-glutamin, can help reduce that effect.
The study (Brain Res Bull. 2013 Jun;95:1-6. doi: 10.1016/j.brainresbull.2013.02.005. Epub 2013 Feb 28.) used rats, that were stressed by water submersion, to illustrate the beneficial effects. The corticosterone levels in the rats were tested. Corticosterones are hormones produced by the adrenal glands in response to long-term induced stresses. Turns out, the rats that were fed theanine displayed lower corticosterone levels both before and after the stress induction.
Where can you find theanine? It is a known component in teas, most notably, Green Tea. Now every time you enjoy your green tea or use your green tea supplements, you know that not only are you supplementing your body's antioxidant levels and boosting metabolism with EGCG, you are giving your body some protection from the ravages of everyday stress! That's just awesome!
Green tea can be an acquired taste. Some opt to consume teas that are blends (I recommend Celestial Seasonings' green tea blends with lemon or mandarin orange), or use supplements in capsule or extract form. There are a lot of companies out there that offer green tea supplements. Be sure to find a reputable company that offers a green tea that is pure and contains 80% polyphenols, 60% catechins, 30% EGCG. This will ensure you receive the maximum benefit from the product.
The amount of tea needed to see major benefits is debated by many. A large proportion suggest the equivalent of 10 cups of green tea each day. While some green tea is definitely better than no green tea, some supplements are quite concentrated and only require a few capsules each day.