Black tea is among one of the most commonly consumed beverages around the world. Beyond just being a refreshing and energizing beverage however, research shows that it has many health benefits too that reduce one’s risk of heart disease.
L-theanine is one of the main constituents of black tea. An amino acid, the substance has been shown to promote relaxation and focus without inducing drowsiness. In 2008, researchers conducted a study that measured the effects of ingesting 50mg of L theanine (equivalent to 2 and a half cups of tea) on brain function using electroencephalography (EEGs). They then compared these results to those from a control group only consuming 100ml of water.
In the end, they found that those who consumed L theanine saw significant increases in activity in their brain’s alpha frequency bands when compared to those in the control group. Increasing activity in this band is associated with higher degrees of relaxation and increased attention spans without feelings of drowsiness.
As stress is known as a major contributing factor towards heart issues, the relaxing properties of L-theanine are able to significantly reduce blood pressure, a key contributor to heart disease. A study conducted in 2012 for example found that L-theanine was able to regulate increases in blood pressure among people who normally experienced higher blood pressure after certain mental tasks.
Further research suggests that drinking black tea may be able to regulate cholesterol levels. A randomized study conducted in 2003 for example found that people with slightly to moderately elevated levels of low-density lipoprotein (LDL) who drank five cups of black tea per day were able to reduce their LDL by 11.1%, making it more effective in reducing LDL than caffeine.
Meanwhile, another study from 47 participants found that those drinking black tea saw significant decreases in their LDL levels compared to those drinking a placebo, and without any negative side effects. The researchers thus concluded that drinking black tea may help to improve cholesterol levels in people at risk of developing heart disease and obesity.