Green tea has a high content of vitamins and minerals. It contains ascorbic acid (vitamin C) in amounts comparable to a lemon. Green tea also contains several B vitamins which are water soluble and quickly released into a cup of tea. Five cups of green tea a day will provide 5-10% of the daily requirement of riboflavin, niacin, folic acid, and pantothenic acid. The same five cups of green tea also provide approximately 5% of the daily requirement of magnesium, 25% of potassium, and 45% of the requirement for manganese. Green tea is also high in fluoride. A cup of green tea provides approximately 0.1 mg of fluoride, which is higher than in fluorinated water. Scientific studies have shown strong evidence that green tea may help reduce the risk of strokes and heart disease, and may also prevent some cancers.