Research is also being done to find out if it may be used as a natural sun block. It may also regulate blood sugar and insulin levels. Oolong tea may also reduce blood pressure and arterial disease possibly by decreasing the clotting tendecy of blood. Black tea is rich in tannins which give it an astringent quality useful in treating diarhea and may help relieve certain types of headaches. All types of Camellia sinensis have stimulant properties, so people who are pregnant or nursing, who have anxiety disorders, who suffer from insomnia or who have an irregular heart beat should limit their daily intake to 1 or 2 cups with the last cup being taken at least 3 hours before bedtime.
Tea is made by infusion or steeping the leaves in boiling water for a short period of time.
Green tea is best made with water just before it reaches a rolling boil and steeped for 2-5 minutes only. If steeped longer too much of the bitter quality will come through in the taste. Oolong and black tea should be made with boiling water and may be steeped for a slightly longer time. To make a strong infusion of black tea to treat diarrhea, steep 2 teaspoons of leaves in a cup of boiling water for 5-7 minutes and drink without sugar or milk. Tea is one of the most popular beverages in the world.