According to a report in the British Daily Mail, a new study has found that if people choose cheap supermarket tea bags for convenience instead of traditional tea leaves, it may lead to long-term health problems. The study found that tea bags sold at major UK supermarkets such as Tesco, Asda, and Sainsbury's can cause drinkers to exceed the daily recommended intake of fluoride, putting them at high risk of bone and dental diseases. Researchers collected 38 tea products and tested their fluoride levels. The data was compared by University of Derby PhD student Laura Chan, Professor Aradhana Mehra, and Professor Paul Lynch. They used ion-selective electrode analysis, a technique that can detect trace elements such as fluoride in liquids. Scientists analyzed dry tea leaves and tea brewed for two minutes with boiling water, and calculated the fluoride intake from drinking four cups of tea or one liter of tea per day.
Researchers found that whether black tea or green tea, supermarket tea bags showed significant differences in fluoride content compared to premium tea brands. Among them, cheap green tea blends had the highest fluoride content, averaging 6 mg per liter. Premium teas had the lowest fluoride levels, averaging 0.7 mg per liter.
However, according to relevant international guidelines, the average daily fluoride intake for adults should not exceed 3–4 mg. Therefore, the fluoride content of many economy tea bags reached 75% to 120% of the daily upper limit.
Excessive fluoride intake can cause a number of health problems. Moreover, fluoride is not only found in tea but also in seafood, toothpaste, and even drinking water in some countries and regions. Some processed foods may also be treated with fluoridated water.
The least harmful effect of excessive fluoride intake may be dental fluorosis, which causes white and brown spots on the enamel, eventually leading to mottled and unsightly teeth. This may be the first sign of fluoride toxicity in the body.
A more serious condition is skeletal fluorosis, a disease that can have severe consequences, including bone and joint pain, muscle weakness, and gastrointestinal disorders. People who consume a total of 10–20 mg of fluoride per day for 10 to 20 years, or 2.5–5 mg per day for 40 years, may develop this condition. In most severe cases, the spine can become completely rigid.
Excessive fluoride intake can also lead to osteoporosis. Additionally, in areas where drinking water contains excessive fluoride, people have a higher incidence of kidney stones. Some researchers even believe that high fluoride exposure in bones can lead to bone cancer in young people. As early as 1992, a study found that in areas with high fluoride levels in drinking water, the incidence of osteosarcoma was 3 to 7 times higher than in normal areas.
Dr. Chan stated: "Tea plants and wild tea plants are 'batteries' for fluoride, especially the leaves, which accumulate most of the fluoride. When tea leaves are harvested, older leaves are usually used to produce low-quality tea products, such as cheap tea bags; young buds and top new leaves are used in high-quality or specialty tea products. Although fluoride is considered an essential trace element for human health, preventing tooth decay and promoting healthy bone growth, excessive fluoride in the daily diet can cause harm. Dental fluorosis, skeletal fluorosis, bone and joint pain, and calcification damage can all occur. People may be drinking tea with too much fluoride and also consuming other fluoride-rich foods in their daily diet without knowing the risks. In both the UK and the US, similar situations have been found, with people who drink too many cheap tea bags having a higher incidence of skeletal fluorosis than the average person. All tea products can be considered a major source of fluoride in the diet, and we urge supermarkets and manufacturers to list fluoride concentrations on packaging nutrition labels."
Therefore, experts are calling for supermarkets and tea producers to consider adding labels such as fluoride concentration on packaging as part of nutritional information disclosure.