High blood pressure, also known as hypertension, can often end with deadly consequences; however people rarely show symptoms of having it. This has earned the disease its nickname "The Silent Killer."

Variations in blood pressure can be a more serious indication that there's something wrong with the cardiovascular system. A sudden fluctuation in blood pressure can be an early warning sign of a stroke or even heart disease.

An article published in the American Journal of Clinical Nutrition claims drinking black tea can substantially reduce the rate of blood pressure variation. Scientists are confident that there is an ingredient in black tea — and not caffeine — can positively affect rapid changes in blood pressure.

The difference between black tea and other types of tea like white and green is that black is more oxidized, a result of the leaves having been aged longer. In the past black tea has been shown to improve mental alertness, prevent Parkinson's disease, and relieve hardening arteries.

To test black tea's effect on blood pressure, an Australian research team conducted an experiment involving 111 men and women who showed signs of prehypertension. Participants were asked to drink three cups of black tea a day than had their blood pressure monitored three times in the span of six months.  

The results of the study showed that drinking three cups of black tea a day altered blood pressure variation by about 10 percent. The effects of drinking black tea were noticeable after the first day and continued over the course of the six months.

Bouts of high blood pressure could be a result of a number of different risk factors including obesity, diabetes, smoking, a high cholesterol diet and lack of exercise. In addition to drinking black tea, experts urge anyone with signs of hypertension or prehypertension to have their blood pressure tested by a physician. Individuals should also maintain a healthy diet, avoid stressful situation,s and limit alcohol and salt consumption.

This study was published in the April 3 edition of the American Society for Nutrition's online journal The American Journal of Clinical Nutrition.