Moderate consumption of coffee, whether unsweetened or sugar-sweetened, was associated with lower risk of death, according to research by a Chinese university.

The research, conducted by a team led by Mao Chen, a professor at the School of Public Health and Tropical Medicine of Southern Medical University in Guangzhou, Guangdong province, was published online by international science journal Annals of Internal Medicine recently.

"Previous observational studies have suggested an association between coffee intake and reduced risk of death, but these studies did not distinguish between coffee consumed with sugar or artificial sweeteners and coffee consumed without," the research report said.

In the new study, data were extracted from the UK Biobank, with follow-up between 2009 and 2018 with 171,616 participants without cardiovascular disease or cancer.

A median follow-up of seven years showed a U-shaped association of unsweetened coffee, sugar-sweetened coffee and artificially sweetened coffee with mortality.

Compared with non-consumers, consumers of various amounts of unsweetened coffee had lower risk of death after adjustment for lifestyle, demographics and social and clinical factors.

The association between artificially sweetened coffee and death was less consistent.

U-shaped associations were also observed for instant, ground and decaffeinated coffee.