# Altitude-Dependent Differences in Non-Volatile Metabolites of Tea Leaves Revealed by Widely Targeted Metabolomics

## TL;DR

This study shows that tea grown at higher altitudes has a distinct chemical profile, supporting the idea that mountain-grown tea is better.

## Contribution

The study reveals altitude-specific metabolic signatures in tea leaves using targeted metabolomics.

## Key findings

- High-altitude tea leaves showed elevated tannins and stress-induced flavonoids.
- Low-altitude samples had higher lipid and total polyphenol contents.
- Over 2300 metabolites were identified, with 116 showing significant differences between altitudes.

## Abstract

Tea is a globally popular beverage, but little is known about how altitude affects its flavor and health benefits. This study investigated the chemical differences between fresh tea leaves grown at low altitudes (350 m) and high altitudes (600 m) using advanced analytical methods. We found significant metabolic differences between the two environments, identifying over 2300 compounds, including key flavor molecules like flavonoids and phenolic acids. High-altitude samples displayed a specialized metabolic signature marked by elevated levels of tannins and stress-induced flavonoids, diverging from low-altitude samples, which possessed higher lipid and total polyphenol contents. These results demonstrated that the traditional belief that “good tea is produced from high mountains” has a solid scientific basis. Our findings provide vital information for tea growers, helping them optimize cultivation methods at different elevations to produce tea with specific, enhanced flavor profiles and health properties.

Tea is produced from the fresh leaves of the tea plant (Camellia sinensis), and the quality of tea is directly dictated by its raw material. Although factors such as tea cultivar, fertilization, and cultivation practices are known to affect fresh leaf quality, the specific influence of altitude remains poorly understood. In this present study, ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was employed to investigate the non-volatile metabolites in fresh tea leaves grown at two different altitudes (350 m and 600 m). A total of 2323 metabolites were identified, with flavonoids and phenolic acids representing the dominant classes. Orthogonal partial least squares-discriminant analysis (OPLS-DA) further revealed 116 differential metabolites between groups. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis indicated that several key pathways were differentially activated, including those related to the biosynthesis of kaempferol, luteolin, and flavones, as well as nucleotides and jasmonic acid metabolism. In addition, marked differences were observed in the accumulation patterns of lipids, phenolic acids, and flavonoids between leaves grown at the two altitudes. These findings provide valuable insights into the role of altitude in shaping the metabolic composition and flavor formation of tea.