The researchers noted: “A large proportion of the general population has blood pressure within the range included in this trial, making results of the trial applicable to individuals at increased risk of hypertension.”
While assessing which components of black tea delivered the hypertensive effects, the team hypothesised that the polyphenols in black tea did by improving endothelial dysfunction.
It had previously been demonstrated that flavonoids were beneficial for endothelial function by increasing nitric oxide and reducing the concentration of the amino acid endothelin.
The findings are consistent with those of a 2021 study led by the University of California and the University of Copenhagen, which found that antioxidants in tea could open ion channels, and relax the muscles that line blood vessels.