What is it that coffee does, exactly, that its elimination from one's diet would require a substitute? Yes, coffee contains caffeine, which is a stimulant, but why do you require a stimulant? Black tea has, per cup, about half the amount of caffeine in it than does coffee, not twice the amount (50mg as opposed to 100mg). So, if it's caffeine you want, you would have to drink twice the amount of Black Tea.
And as for the claim that Black Tea prevents cancer, now that is news. As far as I know, there have never been any scientific studies that conclusively demonstrate any relationship between the drinking of Black Tea and the prevention of cancer. Indeed, many claims have been made about the benefits of Black Tea, but anyone can make claims. There have been European and American studies that showed that short and long-term black tea consumption reverses endothelial vasomotor dysfunction in patients with coronary artery disease. This is believed to be because of the action of the antioxidant flavonoid levels in Black tea. Other than that, there are no scientifically acknowledged benefits to drinking Black Tea.
A report from the October 4, 2006 article from Science Daily reveals that black tea is more effective in reducing the stress hormone levels of people. Study participants who drank black tea in lieu of their usual coffee for six weeks were found to have lower levels of the stress hormone cortisol.
In this study seventy-five young males were given tea to drink in place of their regular caffeinated drinks. (For the control group, the "tea" was not real black tea.) During this time, they were subjected to stressful situations such as visiting nursing homes, being accused of shop-lifting, threat of unemployment, etc., and they had to prepare an argument against the accusations. In each of the situations, their blood pressure levels rose, heart rate and subjective stress ratings. However, fifty minutes after the test, the cortisol levels of those who drank the black tea lowered by 47% compared to the 27% lowering in those who drank the fake tea.
So, black tea proves a good substitute for coffee healthwise. As far as its amont of caffeine, black tea has somewhat less than coffee.
A long-term study by the Netherlands National Institute of Public Health and the Environment found a correlation between regular consumption of black tea and reduced risk of stroke. Researchers looked at data from a study examining the health benefits of foods that are high in flavonoids - phytonutrients with antioxidant benefits. A separate study by Dr. Joseph Vita at Boston's School of Medicine supported these results.
For four months, sixty-six men drank four cups of either black tea or a placebo daily. Dr. Vita concluded that drinking black tea can help reverse an abnormal functioning of the blood vessels that can contribute to stroke or heart attack. Furthermore, improvement in the functioning of the blood vessels was visible within two hours of drinking just one cup of black tea.
Black tea contains more caffeine than green tea but less than coffee. It is therefore considered a good replacement of the coffee, especially in the morning. Note, however, should not consume more than two cups of black tea daily. Drinking to excess, it can cause insomnia, restlessness and nervousness.
Because it has a high content of antioxidants, vitamins and minerals, black tea protects the body from various diseases. Black tea prevents cancer and cardiovascular diseases, contributing to a decrease in the number of cholesterol and blood triglycerides and a reduction in body fat mass. In this way, greatly help in regulating body weight. Also drinking a cup of black tea every day, we can prevent and cure atherosclerosis.