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

Abstract

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.