Health Benefits of Black Tea: 

1- Black tea has 5.25 mg of caffeine per fluid ounce. It is rich in antioxidants known as polyphenols and catechins. (1,3)

2- High amounts of flavan-3-ols, flavonols, theaflavins and gallic acid derivatives present in black tea helps repair coronary artery dysfunctions in heart patients, and prevents heart diseases. (1,2,3,4)

3- The polyphenols in black tea help prevent the formation of potential carcinogens in the body. Such as lung cancer, prostate cancer, and bladder cancer, and others. (1,2,5)

4- Drinking more than one cup of black or green tea daily helps in preventing ischemic strokes. (1,6)

5- Black tea is rich in tannins and other chemicals that have a positive and relaxing effect on the digestive system of the body. This anti-inflammatory quality of the tea is also helpful for curing digestive disorders. (1,2,7)

6- Drinking black tea benefits the skin in three ways. First, it nourishes the skin with vitamins B2, C, and E, with minerals such as magnesium, potassium, and zinc, and essential polyphenols and tannins. Second, its caffeine and some of its other chemical components can kill oral viruses, which helps prevent skin infections (and pimples). Third, black tea has been shown to reduce “mimic wrinkles” and signs of premature aging. (1,2,3,8)

7- Black tea not only fights bacteria but also strengthens the immune system. The rich source of antioxidants in black tea prevents DNA damage by free radical scavenging activity. (1,3,9,10)

8- Black tea lowers triglyceride levels and visceral fats. Thus, a few lifestyle changes along with the consumption of black tea helps in weight loss. It also helps prevent inflammation-induced obesity. (1,11,12)

9- A cup or two of unsweetened black tea taken daily can reduce inflammation, prevent cavities, and stop the growth of bacteria in the mouth. It improves oral health. (1,2,13)

Reference: 

• https://www.organicfacts.net/health-benefits/beverage/health-benefits-of-black-tea.html 

• https://www.thespruceeats.com/black-tea-benefits-765048

• https://ndb.nal.usda.gov/ndb/foods/show/14355

• https://pdfs.semanticscholar.org/fb66/d5157750019447dc2f7b4f3af23e2d408a62.pdf

• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3471195/

• https://www.ncbi.nlm.nih.gov/pubmed/19228856

• https://www.ncbi.nlm.nih.gov/pubmed/21776478

• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1955322/

• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2835915/

• https://www.ncbi.nlm.nih.gov/pubmed/20391028

• https://www.ncbi.nlm.nih.gov/pubmed/25031332

• https://www.ncbi.nlm.nih.gov/pubmed/22508359

• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3841993/