Study: Shifting Precipitation Patterns Affect Tea Flavor, Health Compounds

BOZEMAN, Mont. — A team of researchers including Montana State University professor Selena Ahmed has found that shifting patterns of precipitation affect key chemicals responsible for the flavor and health properties of tea.

Ahmed, assistant professor of health and human performance in the MSU College of Education, Health and Human Development, said the team's research shows that major antioxidant compounds that determine tea health properties and flavor, including epigallocatechin, epigallocatechin gallate, epicatechin gallate, gallocatechin gallate, catechin and gallic acid, fell up to 50 percent in an area of southwest China during an extreme monsoon, while other compounds increased. Household income from the sales of tea grown during the extreme monsoon also dropped by up to 50 percent, Ahmed said.

The findings are based on samples taken from tea gardens in southwest China. The researchers collected samples from two extreme weather events – an extreme drought and an extreme monsoon – and performed a chemical analysis of the samples. The researchers also interviewed tea farmers, who perceived the tea grown during the monsoon to be of lower quality and preferred tea grown outside of the monsoon season.

The findings were published Oct. 6 in PLOS ONE, a peer-reviewed journal of the Public Library of Science. Ahmed was the paper's lead author.

The results of the research, which attracted attention in a recent New York Times story on various animal and plant species around the world that may be threatened by warmer global temperatures, could have significant impacts on farmers' livelihoods, both in China and around the globe, Ahmed said.

"Extrapolating findings from this study with climate scenarios suggests that tea farmers will face increased variability in their livelihoods with the increased prevalence and intensity of extreme droughts and heavy rains associated with climate change," Ahmed said. "The study has compelling implications not only for tea, but also for all other food and medicinal plants for which changes in weather patterns can alter flavor and nutritional and medicinal properties."

The study's co-author, Rick Stepp, an associate professor of cultural anthropology at the University of Florida, added that the team's research goes beyond the chemical analysis of the tea.

"We are very interested in understanding not only how climate impacts tea quality and farmer livelihoods, but also the factors that enable farmers to adapt to climate risk," Stepp said.

Tea is a multibillion dollar industry, with many consumers choosing to drink it in order to receive health benefits.

In the United States, tea purchases have increased for 20 consecutive years and annual sales have surpassed $2.2 billion, with 160 million Americans drinking tea on any given day, according to the Tea Association of the USA, a New York-based industry group.

In fact, today tea is the most widely consumed beverage in the world, second only to water, according to the University of Maryland Medical Center. Hundreds of millions of people around the world drink tea, which has been cultivated for centuries, beginning in China and India.

Green tea is recognized for its many health benefits that are attributed to powerful antioxidants called polyphenols, including the catechin compounds Ahmed studies.

Antioxidants fight free radicals, or damaging compounds in the body that change cells, damage DNA, and even cause cell death. According to the University of Maryland Medical Center, many scientists believe that free radicals contribute to the aging process and the development of many health problems, including cancer and heart disease. Research suggests that antioxidants such as polyphenols in green tea can help prevent cardiovascular disease, burn calories and even ward off some types of cancer. In addition, green tea has been used to help improve heart health, regulate body temperature and blood sugar, and promote digestion, among other uses.