To make black tea, the leaves are wilted, bruised, rolled, and fully oxidized. Black tea accounts for 75 percent of the tea consumed in the world.
Oxidization happens when the leaves are exposed to the air for long periods. Enzymes break down the chemicals in the leaves, producing their brown coloring and familiar smell.
Green tea, in contrast, is made from leaves that are not oxidized.
Oxidization may give black tea nutritional benefits that are not present in green tea, such as reducing the risk of several cancers, protecting the heart against atherosclerosis, and maintaining a healthy blood pressure.
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Nutritional breakdown of black tea
Research has suggested that black tea possesses antioxidant qualities, which can help to combat disease.
According to the National Cancer Institute, tea contains:
- alkaloids (caffeine, theophylline, and theobromine)
- amino acids
- minerals and trace elements
- volatile organic compounds, which contribute to its odor and taste
Black tea also contains polyphenols, chemical compounds that protect plants from ultraviolet radiation or harmful, disease-causing pathogens. Flavonoids are a kind of polyphenol. The benefits of red wine are thought to be related to flavonoids.
When consumed by humans, these polyphenols have an antioxidant effect. Antioxidants can counter the activity of free radical cells. Free radicals can harm health and damage, change, and even kill cells in the body.
Free radicals contribute to the development of many diseases and conditions, such as atherosclerosis and some cancers.
Possible health benefits of tea
Most studies on the potential health benefits of tea have focused on green tea.
However, taking into account the oxidization process involved in making black tea, some studies have investigated the unique benefits that this may provide.
Few studies on black tea are conclusive, as the tests have involved giving animals larger doses than would normally be consumed in an average human diet.
Food and drink companies may overemphasize the health benefits of antioxidants to support sales.
The oxidation process in black tea, which lends the leaves their brown colour, may be linked to black tea's potential health benefits.
A 2004 study on hamsters by researchers at the University of Maryland linked the antioxidants available in green and black tea to combatting the free radicals that cause atherosclerosis.
Three cups of black tea per day were estimated to reduce the risk of atherosclerosis by 11 percent.
A review published in the European Journal of Clinical Nutrition suggests that drinking 3 or more cups of tea a day might offer protection against coronary heart disease.
Decreasing cancer risk
Findings cited by the National Cancer Institute suggest that the polyphenols in tea may decrease tumor growth. Laboratory tests and animal studies suggest they may protect against damage caused by ultraviolet B (UVB) radiation.
Black tea has been linked to cancer in a similar way to green tea, although it affects fewer types of cancer. Studies have also indicated that black tea may have a positive impact on bladder, lung, and prostate cancer.
As is the case in many studies related to tea and cancer, the results are inconclusive.
Separate studies have found conflicting outcomes as far as black tea and cancer are concerned, noting that black tea both increased and decreased the risk of lung cancer in differing studies.
Researchers have not been able to explain how antioxidants and cancer cells interact to reduce the risk of cancer development.
However, one team concluded that drinking six cups of tea a day could enhance antioxidant status.
Reducing blood pressure
In a study carried out by the University of Western Australia in 2012, black tea was shown to reduce diastolic and systolic blood pressure. It also canceled out the impact on blood pressure of a high-fat meal.
However, a global manufacturer of edible goods, including teas, funded this study. As the backing of the research is not impartial, readers are advised to approach such studies with caution.
Ways of consuming tea
Black tea has demonstrated positive effects on atherosclerosis and blood pressure. However, research in this area has not been conclusive.
More research is needed to confirm its active health benefits, but black tea remains a more healthful alternative to many products when seeking a daily caffeine boost.
Caffeine is a stimulant that can boost focus and energy throughout the day.
People can consume more black tea without affecting health than some caffeine-laden beverages.
It has a low calorie count, and it can be used to add flavor to dishes without adding sugar or salt to the diet.
Tips for using tea
Here are 4 tips to incorporate black tea into solid meals.
Tip 1: Use tea instead of soup stock
Black tea can add a smoky flavor to soups with red meat or mushrooms.
Tip 2: Add tea to poaching liquids
Poaching food in black tea infuses the aroma into the protein of the food. Mushrooms poached in lapsang souchong black tea can be a particularly flavorsome option.
Tip 3: Cook beans and grains with tea
Swapping water for tea when cooking rice or beans adds a smoky nuance to their flavor.
Tip 4: Tea works as part of a dessert
The distinctive flavor of tea can be infused into warmed, whole-fat milk and added to puddings or custards. Infusing Earl Grey black tea into chocolate custards, for example, can give great results.
Potential health risks
Black tea contains some minerals that are poisonous in high doses. Avoid brewing for over three minutes.
All brewed tea contains minerals that, in excess, can be poisonous.
Lead and aluminum are present in tea. These heavy metals, in large doses, can be toxic to humans. Minor traces of arsenic and cadmium can be found in some teas, but not in harmful quantities.
Black tea has particularly high levels of manganese, which is toxic in excess.
The longer tea is left to brew, the higher the concentration of these toxic elements, so it is advisable only to brew tea for a maximum of 3 minutes.
Depending on where and how the tea is grown, there may also be traces of pesticides in the leaves, so moderate consumption is advised. A maximum of 10 cups per day is recommended.
Effects of caffeine
Black tea contains 2 to 4 percent caffeine.
Excessive caffeine intake may also lead to to:
- cardiac arrhythmia, or an irregular heartbeat
- diarrhea and irritable bowel syndrome
- eye pressure, and possible glaucoma
- affected blood sugar, and potential diabetes
- increased blood pressure
- increased dumping of calcium in the urine, and therefore weakened bones and possible osteoporosis
Regular tea drinkers who experience any of the above symptoms should consider reducing their tea consumption. If symptoms continue, they should see a doctor.
Tea has been found to decrease the bioavailability of iron when taken with meals. This means that it reduces the body's ability to absorb iron.
People with a history of iron deficiency should take care to not consume tea when taking iron supplements or an iron-rich meal.
They should also leave an hour between eating and drinking black tea.
Interactions with drugs and supplements
Black tea has been known to interact with a range of different medications and supplements.
- MAO inhibitors, used to treat depression
- stimulants such as Ritalin
- drugs to prevent arrhythmias, insomnia, heartburn, ulcers, or anxiety
- folic acid
Tea might increase blood pressure and heart rate if consumed with other stimulants, and it may reduce absorption of folic acid.
Iced teas and ready-to-drink teas may not be as healthful as plain black tea, as the composition is different. Adding sugar to tea also reduces the health benefits.
Always speak to a physician if black tea is a part of your diet and you are taking ongoing medications.