Roots of Hydroponically Grown Tea (Camellia sinensis) Plants as a Source of a Unique Amino Acid, Theanine

The beneficial effects of green tea are well documented. However, most research has reported the
effects of green tea brewed solely from leaves or leaf extracts. We focused on tea roots and
developed a hydroponic system to explore the effect on roots that biosynthesize one of the rarest
functional amino acids, theanine. The level of theanine in tea roots was much higher than in leaves,
which was analyzed using HPLC. Moreover, a higher level of theanine was detected in white rootlets
than in lignified roots. Thus, tea roots cultured hydroponically in a controlled environment might be
considered a natural drug containing theanine, which could lead to synergistic effects with other
ingredients of the root. This novel medicinal material from the roots demonstrates a significant
medical function for tea that extends beyond its leaves.