Black Tea

Uses

Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate. The effectiveness ratings for BLACK TEA are as follows:

Likely effective for…

• Mental alertness. Drinking black tea and other caffeinated beverages throughout the day helps to keep people alert and improve attention, even after extended periods without sleep. The effect appears to increase with an increasing amount of caffeine in the caffeinated beverages.

Possibly effective for…

• Low blood pressure. Black tea contains caffeine. Drinking beverages containing caffeine helps increase blood pressure in older people who have low blood pressure after eating.
• Heart attack. Some research shows that people who drink black tea have a lower risk of having a heart attack. Also, people who have been drinking it for at least a year before having a heart attack seem to be less likely to die after having a heart attack.
• Weak and brittle bones (osteoporosis). Early research suggests that older women who drink more black tea have stronger bones than those who drink less. Drinking more also seems to be linked with a lower risk of hip fracture in older men and women.
• Ovarian cancer. Women who regularly drink tea, including black tea or green tea, appear to have a lower risk of developing ovarian cancer compared to women who never or rarely drink it.
• Parkinson disease. Some research shows that people who drink caffeinated beverages such as coffee, tea, and cola have a lower risk of Parkinson’s disease. The lower risk seems to be directly related to the dose of caffeine in men but not women. Drinking it also appears to be linked with a reduced risk of Parkinson’s disease among people who smoke cigarettes.

Possibly ineffective for…

• Bladder cancer. People who drink tea, including black tea and green tea, do not seem to have a lower risk of bladder cancer compared to those who don’t drink it.
• Breast cancer. People who drink it do not seem to have a lower risk of breast cancer compared to those who don’t drink it.
• Colon cancer, rectal cancer. Some early research suggests that drinking black or green tea might be linked with a lower risk of colon and rectal cancer. However, most research shows that drinking tea is not linked with a lower risk of colon and rectal cancer. In fact, some early research suggests that drinking higher amounts might be linked with an increased risk of colon and rectal cancer.
• Diabetes. Early research suggests that taking an extract of black and green tea does not improve average blood sugar levels in people with diabetes. Other early research suggests that drinking at least one cup per day is not linked with a lower risk of developing type 2 diabetes in Japanese adults.
• Cancer of the lining of the uterus (endometrial cancer). Women who drink more black tea do not seem to have a lower risk of developing endometrial cancer compared to those who drink less.
• Cancer of the esophagus. People who drink higher amounts do not seem to have a lower risk of developing cancer of the esophagus compared to those who drink less. In fact, some research suggests that drinking more or stronger black tea might increase the risk of cancer of the esophagus.
• Stomach cancer. Some early research suggests that drinking black or green tea might be linked with a lower risk of stomach cancer. However, most research shows that people who drink black or green tea do not have a lower risk of stomach cancer. In fact, some early research suggests that people who drink higher amounts might have an increased risk of stomach cancer compared to those who drink less.
• Lung cancer. Early research found that drinking it is not linked with a reduced risk of lung cancer and may even be linked with an increased risk.

Insufficient evidence to rate effectiveness for…

• Hardening of the arteries (atherosclerosis). Early research suggests that people who drink black tea have a reduced risk of having their arteries become hardened compared to those who don’t drink it. This link is stronger in women than men.
• Heart disease. Most research suggests that drinking black tea does not protect against heart disease or death from heart disease. But not all research agrees. Some research in people who already have heart disease suggests that drinking it is linked with a higher risk of heart disease becoming worse or causing death.
• Cavities. Early research suggests that rinsing with a black tea extract might help prevent cavities.
• Diarrhea. Early research shows that taking black tea as tablets reduces watery stool in children with diarrhea.
• High levels of cholesterol or other fats (lipids) in the blood (hyperlipidemia). It is still not clear if drinking black tea helps to reduce levels of cholesterol in the blood. Some research shows that it might reduce total cholesterol and low-density lipoprotein (LDL or “bad”) cholesterol in people with normal or high cholesterol levels. However, other research shows that drinking it does not have these effects.
• High blood pressure. Some research shows that drinking 3-5 cups per day of black tea or taking an extract can reduce blood pressure by a small amount in people with normal or high blood pressure. But not all research agrees. And the small reduction in blood pressure might not be clinically meaningful.
• Kidney stones. Women who drink one cup of tea, such as black tea, per day seem to have a lower risk of developing kidney stones compared to those who don’t drink it.
• Obesity. Early research shows that taking a product containing the extract plus many other ingredients for 12 weeks does not reduce body weight in overweight adults.
• Pancreatic cancer. Some early research suggests that drinking black tea is linked with a reduced risk of pancreatic cancer. However, other research shows conflicting results.
• Prostate cancer. Early research suggests that drinking it is linked with a reduced risk of prostate cancer.
• Kidney cancer. Early research suggests that people who drink higher amounts of black or green tea have an increased risk of developing kidney cancer.
• Stress. Early research suggests that drinking black tea for 6 weeks does not improve blood pressure, heart rate, or feelings of stress ratings while performing stressful tasks.
• Stroke. Black tea contains chemicals called flavonoids. Early research suggests that eating a diet that contains flavonoids is linked with a lower risk of stroke.
• Headache.
• Stomach disorders.
• Vomiting.
• Increasing response to sexual stimuli.
• Other conditions.

More evidence is needed to rate the effectiveness for these uses.

Side Effects Of Black Tea

When taken by mouth: Drinking moderate amounts of black tea is LIKELY SAFE for most adults. Drinking too much black tea, such as more than five cups per day, is POSSIBLY UNSAFE. High amounts can cause side effects due to the caffeine. These side effects can range from mild to serious and include headache, nervousness, sleep problems, vomiting, diarrhea, irritability, irregular heartbeat, tremor, heartburn, dizziness, ringing in the ears, convulsions, and confusion. Also, people who drink black tea or other caffeinated beverages all the time, especially in large amounts, can develop psychological dependence. Drinking very high amounts of black tea containing more than 10 grams of caffeine is LIKELY UNSAFE. Doses this high might cause death or other severe side effects.

Warnings & Precautions

• Pregnancy and breast-feeding: If you are pregnant or breast-feeding, drinking black tea in small amounts is POSSIBLY SAFE. Do not drink more than 2 cups a day. This amount of tea provides about 200 mg of caffeine. Consuming more than this amount during pregnancy is POSSIBLY UNSAFE and has been linked to an increased risk of miscarriage, increased risk of sudden infant death syndrome (SIDS), and other negative effects, including symptoms of caffeine withdrawal in newborns and lower birth weight.
• If you are breast-feeding, drinking more than 3 cups a day is POSSIBLY UNSAFE and might cause your baby to become more irritable and have more bowel movements.
• Children: Black tea is POSSIBLY SAFE when taken by mouth by children in amounts commonly found in foods.
• Anemia: Drinking black tea may make anemia worse in people with iron deficiency.
• Anxiety disorders: The caffeine might make these conditions worse.
• Bleeding disorders: There is some reason to believe that the caffeine in black tea might slow blood clotting, though this hasn’t been shown in people. Use caffeine cautiously if you have a bleeding disorder.
• Heart problems: Caffeine in black tea can cause irregular heartbeat in certain people. If you have a heart condition, use caffeine with caution.
• Diabetes: The caffeine in black tea might affect blood sugar. Use with caution if you have diabetes.
• Diarrhea: Black tea contains caffeine. The caffeine, especially when taken in large amounts, might worsen diarrhea.
• Seizures: Black tea contains caffeine. There is a concern that high doses of caffeine might cause seizures or decrease the effects of drugs used to prevent seizures. If you have ever had a seizure, don’t use high doses of caffeine or caffeine-containing supplements.
• Glaucoma: Drinking caffeinated black tea increases the pressure inside the eye. The increase occurs within 30 minutes and lasts for at least 90 minutes.
• Hormone-sensitive condition such as breast cancer, uterine cancer, ovarian cancer, endometriosis, or uterine fibroids: Black tea might act like estrogen. If you have any condition that might be made worse by exposure to estrogen, don’t use it.
• High blood pressure: The caffeine might increase blood pressure in people with high blood pressure. However, this doesn’t seem to occur in people who regularly drink black tea or other caffeinated products.
• Irritable bowel syndrome (IBS): Black tea contains caffeine. The caffeine, especially when taken in large amounts, might worsen diarrhea and might worsen symptoms of IBS.
• Brittle bones (osteoporosis): Drinking caffeinated black tea can increase the amount of calcium that is flushed out in the urine. This might weaken bones. Don’t drink more than 300 mg of caffeine per day (approximately 2-3 cups). Taking extra calcium may help to make up for calcium losses. Older women who have a genetic condition that affects the way they use vitamin D should use caffeine with caution.
• Overactive bladder: Drinking caffeinated black tea might increase the risk of developing an overactive bladder. Caffeine might also worsen symptoms in people with overactive bladder.

Dosage Of Black Tea

An 8-ounce serving provides from 40-120 mg of caffeine, the active ingredient. The following doses have been studied in scientific research: BY MOUTH:

• For mental alertness: 1-3 cups of black tea containing 30-100 mg of caffeine.
• For heart attack: At least 1 cup per day.
• For ovarian cancer: At least 2 cups per day.

Other

Consult your doctor or pharmacist Source All information has been provided courtesy of MedLinePlus from the National Library of Medicine and from the FDA.