What Happens To Your Body When You Drink Black Tea Every Day

Move over, coffee; there's another caffeinated beverage that's steadily gaining popularity in the United States — tea. According to the Tea Association of the United States of America, in 2019 Americans consumed 84 billion servings of tea, and roughly 80% of Americans are regular tea drinkers. The United States is the third-largest importer of tea in the world. The vast majority of tea enjoyed in the United States — about 84% — is black tea. And when it comes to preparation, iced is the clear favorite, representing 75%–80% of all tea consumed.

There are five types of true tea: black, green, white, oolong, and pu-erh. (Sorry herbal tea lovers, you're not drinking the real deal.) All five come from the tea plant, Camellia sinensis, and are differentiated by when the leaves are picked and how they're processed afterward. Black tea comes from mature leaves that have been oxidized and fermented before processing. It's usually used as the basis for iced tea, chai tea, and other flavored brews. It has a bold flavor and the most caffeine of any tea variety (via WebMD).

In addition to its delicious taste, black tea appears to have a number of health benefits. But that doesn't mean there aren't risks, as well, especially if you drink tons of the stuff. So what exactly does drinking black tea every day do to your body?

Drinking black tea every day will keep you hydrated

Getting enough water does more than simply quench your thirst. Staying properly hydrated helps deliver nutrients to cells, maintain body temperature, fight infection, lubricate joints, and boosts your mood, among other things (via the Harvard T. H. Chan School of Public Health). That's not surprising, considering about 60% of the human body is actually water. Even "bone dry" bones are 31% water (via the U.S. Geological Survey). The Mayo Clinic recommends adult women get about 11.5 cups (2.7 liters) of water a day, while adult men should aim for 15.5 cups (3.7 liters). But this is just a baseline suggestion; factors such as exercising, a hot environment, or pregnancy can substantially increase fluid needs.

If you're not a big fan of regular old H2O, the good news is that tea is just as hydrating as plain water, according to a 2011 study published in the British Journal of Nutrition. The researchers noted that, although the caffeine in black tea has often been considered dehydrating, their findings indicated that tea and plain water were almost identical in their ability to provide hydration.

If you want to lower your caffeine intake, consider drinking black tea every day

If you're trying to kick your coffee or energy drink habit but either can't or don't want to give up caffeine entirely, you may be able to wean yourself down to a more reasonable amount by switching to black tea. According to research reported on by The Washington Post in 2015, the average American adult consumes between 122 milligrams and 225 milligrams of caffeine a day. Side effects of consuming too much caffeine can include anxiety, sleep problems, increased heart rate and blood pressure, and, ironically, fatigue (via Healthline).

So, how much caffeine is in your tea? While a 1-ounce espresso has about 64 milligrams of caffeine and an 8-ounce brewed coffee has approximately 96 milligrams, an 8-ounce cup of black tea has only 47 milligrams. If you're particularly sensitive to caffeine, you can opt for decaf black tea, which has only 2 milligrams per 8-ounce serving (via the Mayo Clinic). According to Healthline, tea also contains small amounts of several other stimulants that have caffeine-like effects. These include the organic compounds theophylline and theobromine and the amino acid L-theanine.

Give your body the antioxidants it needs every day

Green tea may be the poster child for antioxidant-rich beverages, but black tea is no slouch in this department. In fact, tea has about 8 to 10 times the antioxidant power of fruits and vegetables. Like green tea, black tea contains a wide variety of flavonoids (plant compounds) with potent antioxidant effects, including thearubigins, epicatechins, and catechins (via WebMD). 

In a 2010 paper published in Nutrition Journal, researchers established the total antioxidant content of more than 3,100 foods and beverages, including tea. Brewed black tea had an average of 1 mmol of antioxidants pr 100 grams of tea. (For comparison, apple juice had 0.27 mmol/100 grams and green tea had 1.5 mmol/100 grams.)

But what exactly do antioxidants do and why are they so important for good health? Antioxidants are chemicals that protect the body against damage from free radicals. Free radicals are highly unstable atoms of oxygen that try to "steal" electrons from other molecules in the body. This destabilizes the molecules and creates a chain reaction that leads to damage throughout the body, a process known as oxidative damage or oxidative stress. Substances that produce free radicals can be found in food and in our environment, and free radicals are also created as the byproduct of natural chemical processes in the body. Antioxidants are able to give free radicals the electrons they want without becoming destabilized themselves (via Livescience).

Drinking black tea every day may upset your stomach

For some people, drinking black tea — especially first thing in the morning on an empty stomach — can cause a lot of tummy trouble. The culprit? Tannins. These bitter and astringent compounds belong to a larger group of plant substances called polyphenols. While the tannins in wine tend to get the most attention, black tea is also high in tannins (although the exact amount will vary significantly based on quality of the tea leaves, preparation, and steeping time). In particular, black tea contains large amounts of two groups of tannins called theaflavins and thearubigins. In addition to giving black tea its dark color, these two types of tannins appear to have potent antioxidant properties. Other tannins in black tea may promote the growth of beneficial bacteria and protect against cancer (via Healthline).

While tannins may have numerous health benefits, they can also cause nausea on an empty stomach, especially for those with more sensitive digestive systems. To avoid an upset stomach, Healthline recommends adding milk to your tea or having it with food. Tannins easily bind to carbohydrates and proteins, which reduces the queasiness they cause.

The beneficial bacteria in your gut may get a boost

Just because drinking black tea on an empty stomach may leave you feeling a bit queasy doesn't mean it's bad for gut health. In fact, black tea may actually support the beneficial bacteria in your digestive tract.

According to a 2016 paper published in Current Opinions in Gastroenterology, the gut microbiome is an ecosystem of billions of microorganisms (mostly bacteria) that resides in your large intestine. It performs a number of important functions, including helping to break down food, producing certain vitamins, and protecting the body against foodborne pathogens. Everyone's gut microbiome is unique, but for optimal health it's important that this collection of microorganisms be large and diverse.

A 2011 paper published in Food Reviews International noted that dietary polyphenols (found in a number of foods and beverages, including tea) may support a healthy microbiome by promoting the growth of friendly bacteria while simultaneously hindering the development of dangerous bacteria such as Salmonella and H. pylori. UCLA Health noted that "black tea polyphenols, which are too large to be absorbed in the small intestine, stimulate the growth of gut bacteria and the formation of short-chain fatty acids, a type of bacterial metabolite (by-product) that have been shown to alter the energy metabolism in the liver."

Protect your heart health by drinking black tea every day

Heart disease is the leading cause of death in the United States. According to the Centers for Disease Control and Prevention (CDC), about 655,000 Americans die each year of heart disease — one death every 36 seconds. High blood pressure, high cholesterol, and diabetes are all major risk factors for heart disease, but the good news is that regularly drinking black tea can help prevent or reverse these conditions.

In a 2012 study published in Preventive Medicine, researchers had participants drink three cups (600 ml total) of black tea a day for 12 weeks and then assessed a number of risk factors for cardiovascular disease. On average, subjects experienced a 35.8% drop in triglycerides, an 18.4% decrease in fasting blood glucose levels, and a 16.6% improvement in their LDL/HDL cholesterol ratio. (This is a ratio of "bad" to "good" cholesterol.) Individuals also experienced a 20.3% increase in HDL cholesterol. The researchers attributed these improvements to the tea's high levels of antioxidants including gallic acid derivatives and theaflavins.

But a single cup a day probably won't keep the cardiologist away. According to a 2007 paper published in the European Journal of Clinical Nutrition, it takes at least three cups of tea a day to reduce your risk for cardiovascular disease.

Drinking black tea every day reduces your risk for stroke

Stroke is the fifth leading cause of death in the United States. According to the Centers for Disease Control and Prevention (CDC), 147,810 people died of stroke in 2018. Roughly 7.8 million Americans (3% of the population) will have at least one stroke in their lifetime. There are three types of stroke. Ischemic strokes are the most common and occur when the blood vessels supplying the brain become blocked with arterial plaque or a clot. A transient ischemic attack (TIA), also known as a "mini-stroke," is similar, but the blockage is only temporary and does not cause permanent brain damage. A hemorrhagic stroke occurs when a blood vessel leaks or ruptures (via the Mayo Clinic). The good news is that, according to a 2017 paper published in Morbidity and Mortality Weekly Report, 80% of strokes are preventable. That's where black tea comes in.

In a 2013 study published in the Annals of Epidemiology, researchers followed almost 75,000 individuals for approximately 10 years to see how different diet and lifestyle factors affected their risk for stroke. They found that black tea drinkers were about 21% less likely to have a stroke. Specifically, they were 20% less likely to have an ischemic stroke and 32% less likely to have a hemorrhagic stroke.

Prevent diabetes by drinking black tea every day

Black tea appears to be helpful at warding off type 2 diabetes in several ways. In a 2012 study published in Preventive Medicine, researchers found that drinking three cups of black tea a day for 12 weeks caused an 18.4% decrease in fasting blood sugar levels. And, in a 2002 in vitro (test-tube) study published in the Journal of Agricultural and Food Chemistry, researchers found that black tea increased insulin activity by more than 15-fold. What exactly is in black tea that's making cells so receptive to insulin? The study authors concluded: "Several known compounds found in tea were shown to enhance insulin with the greatest activity due to epigallocatechin gallate followed by epicatechin gallate, tannins, and theaflavins."

One important caveat: If you like your tea on the sweeter side or consistently opt for ready-to-drink, pre-bottled teas, you're likely getting a big dose of sugar. According to Healthline, eating a diet high in sugar can increase your risk for diabetes both directly and indirectly. Fructose, a type of simple sugar that makes up half of regular table sugar, can damage the liver, which in turn can lead to insulin resistance. This in turn makes it difficult for your body to properly control blood sugar levels. Eating too much sugar can also lead to weight gain and more belly fat, both of which are risk factors for diabetes.

Can drinking black tea every day help prevent breast cancer?

Breast cancer is the most commonly diagnosed cancer in women, and approximately 1 in 8 American women will have breast cancer during their lifetime. An estimated 281,550 new cases of invasive breast cancer will be diagnosed in women in 2021, and approximately 43,600 women die each year of breast cancer. Although much less common, breast cancer also affects men. In 2021, roughly 2,650 men will be diagnosed with the condition (via breastcancer.org).

A 2004 study published in the European Journal of Cancer concluded that the polyphenols (antioxidant plant compounds) in black tea may help prevent the spread of estrogen-dependent breast tumors. Specifically, the polyphenol theaflavins appear to hamper the activity of aromatase, an enzyme that converts other hormones into estrogen, which hormone-dependent cancers need to spread. It's important to note, however, that this experiment was performed on cells in a test tube, so it's unclear if black tea would have the same effect in a real-world setting.

Another study, published in 2006 in Anti-Cancer Agents in Medicinal Chemistry concluded that the polyphenols in black and green tea can prevent the development and spread of cancer cells in a number of ways, including triggering apoptosis, a process by which diseased or damaged cells "self-destruct" before they can cause harm.

Drinking black tea every day may keep you looking young

If you're worried about aging, you're not alone. The results of a 2017 survey published in the New York Post showed that 28% of women under 25, 42% of women aged 25 to 34, and 54% of women between the ages of 35 and 44 worried regularly about how they're aging. But, believe it or not, the fountain of youth might actually be a cup of black tea.

When it comes to the physical signs of aging, collagen plays an important role. That's because collagen, a protein found throughout the body, provides structure to our skin, in addition to performing many other important functions (via Healthline). As we age, our body's ability to create new collagen decreases, leading to saggy, wrinkled skin (via the Huffington Post). But the flavonoid and polyphenol compounds in black tea appear to encourage production of new collagen. 

A 2014 paper published in Toxicological Research noted that these compounds can effectively combat the signs of skin aging and that black tea, along with white tea, had more anti-wrinkle power than green tea. In another study, published in 2021 in the Journal of Dermatological Science, researchers concluded that polyphenols helped support the extracellular matrix (a network of proteins that supports the skin) by encouraging the laying down of collagen and elastin fibers. (Elastin is a protein that, as the name implies, gives skin its stretchiness.)

You may not want to drink black tea every day if you're low in iron

Iron deficiency is extremely common, affecting approximately 20% of nonpregnant women, 50% of pregnant women, and 3% of men (via WebMD). In fact, according to the Iron Disorders Institute, iron deficiency is the most prevalent nutritional deficiency in the world. It can lead to anemia (low red blood cell count), which can cause fatigue, shortness of breath, dizziness, headaches, and weakness. Iron deficiency can be caused by inadequate iron intake, increased demand (for example, during pregnancy), blood loss (such as heavy periods), and difficulty absorbing iron. Anemia can be serious; the condition kills more than 5,000 Americans a year (via the Centers for Disease Control and Prevention).

Black tea isn't the best beverage choice if you're already iron deficient. For starters, caffeine appears to have a modest negative effect on iron absorption. More importantly, however, the polyphenols (chemicals found in plants) and tannins found in tea can block the uptake of iron by binding to the mineral during digestion. In fact, these compounds can inhibit iron absorption by up to 90%. If you're getting plenty of iron in your diet and don't have any underlying conditions that predispose you to iron deficiency, there's likely no need for concern, but if you're already struggling with anemia, it's probably best to keep your tea consumption to a minimum (via Healthline).

Good news when it comes to bone health

In the past, health experts feared that drinking black tea might lead to weakened bones because several studies linked caffeine consumption with negative effects on calcium metabolism. Caffeine appeared to decrease calcium absorption and increase how much calcium was lost in urine. More recent research, however, indicates that caffeine's effects on calcium are very modest, and there's little to worry about if you're getting enough calcium in your diet or via supplements (via American Bone Health).

But adding calcium-rich milk to your tea is still a good idea to help strengthen your skeleton. According to the American Osteoporosis Foundation, 10 million Americans have osteoporosis and another 44 million have osteopenia (a "pre-osteoporosis" condition marked by low bone density). One in two women and one in four men will break a bone at some point in their life because of osteoporosis. if you think osteoporosis is something you don't need to worry about until you're much older, think again. As WebMD explained, bone thinning can happen at any age and often has no symptoms until the first broken bone. While the hormonal changes of menopause put women at significantly higher risk for osteoporosis, a number of factors can increase an individual's chances of getting osteoporosis at a younger age. These include low bodyweight, smoking, not getting enough exercise, a history of eating disorders, celiac disease, and steroid use.

Drinking black tea every day could lead to kidney stones

Although the caffeine in tea may not negatively affect bone health as was once feared, there's still some bad news when it comes to tea and calcium, thanks to black tea's high oxalate content. According to Healthline, oxalate (oxalic acid) is an organic compound found in many plant foods. Oxalate binds to minerals — usually calcium — to create a salt, and these salts leave the body through both stool and urine. In some individuals, however, these salts collect in the kidneys and become kidney stones.

While several substances can concentrate in the kidneys and become stones, the National Kidney Foundation noted that calcium oxalate accounts for the majority of stones. These stones can be extremely painful to pass and may require surgical removal. They're also much more common than you might think. Roughly 9% of women and 11% of men will get kidney stones at least once in their lives, and having one kidney stone puts you at much higher risk for additional stones. Kidney stones increase your risk for chronic kidney disease.

A 2002 study published in the Asia Pacific Journal of Clinical Nutrition found that teabags of black tea contained an average of 4.68 milligrams of oxalate per gram of tea, while loose leaf black tea contained 5.11. This is significantly higher than the oxalate content of green, oolong, or white tea. The longer you steep tea, the more oxalate it will contain.

You may be getting too much fluoride if you drink black tea every day

Fluoride does wonders for protecting your teeth, which is why it's likely in your tap water and your toothpaste. According to Healthline, fluoride helps rebuild weakened tooth enamel, slows the loss of minerals from enamel, prevents the growth of cavity-causing bacteria, and can even reverse the early signs of tooth decay. But you can definitely get too much of a good thing. As Healthline explained, excess fluoride can lead to white spots on your teeth known as dental fluorosis. Although these spots are simply a cosmetic issue, too much fluoride can also lead to skeletal fluorosis, which is much more serious. Skeletal fluorosis causes joint pain and stiffness, changes to bone structure, and calcification (hardening) of ligaments. Getting too much fluoride can also play a role in thyroid disease, neurological issues, acne, and infertility (via Medical News Today).

The tea bush, Camellia sinensis, from which all types of tea (including black) are made, is very good at taking up fluoride from the soil and water. In fact, research conducted by Washington University School of Medicine in 2005 showed that some teas contain as much as 6.5 parts per million (ppm) of fluoride — well over the FDA's limit of 2.4 ppm for beverages and the EPA's guideline of 4 ppm for drinking water.