As a nutrition support pharmacist, you may receive questions about the benefits and potential harms of consuming black tea. Black tea is commonly consumed in amounts of 1-4 cups per day and can interfere with iron absorption in iron-deficient individuals. Furthermore, adding milk to black tea may reduce some of its beneficial cardiovascular effects by potentially binding with and reducing the absorption of flavonoids. The clinical significance of this interaction requires further investigation.
Due to its caffeine content, it's important for mothers to monitor their intake and aim for moderate consumption. During pregnancy, moderate black tea consumption is possibly safe, but caffeine intake should be below 300 mg daily (equivalent to approximately 3 cups). Excessive black tea intake while lactating can affect iron metabolism and folic acid bioavailability. Adverse effects of black tea include diuresis, gastric irritation, and insomnia.
A recent study conducted in the United Kingdom found that drinking at least 2 cups of black tea daily can have a modest reduction in the overall risk of death, especially from heart disease or stroke. The study followed nearly 500,000 adults for about 11 years and took into account lifestyle and genetic factors. It was discovered that drinking more than 2-3 cups of tea per day did not provide additional benefits. Interestingly, these findings differ from previous research that mainly focused on green tea in Asian countries. Black tea, which is more popular in Europe and the US, also seems to offer similar benefits. Green tea and black tea come from the same plant (Camellia sinensis) but are prepared differently. Green tea contains a compound called epigallocatechin gallate (EGCG), known for its health benefits, while black tea, being fermented, is rich in theaflavins, which are believed to have positive effects on heart health and may help prevent cancer.
References
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