Tea vs. Dehydration: Unveiling the Facts | Signos

Tea in moderate amounts is not dehydrating and can be beneficial in preventing chronic diseases.

Sarah Bullard, MS, RD, LD
— Signos
Dietitian and Nutrition Writer
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Updated by

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Science-based and reviewed

April 23, 2024
March 12, 2023
— Updated:

Table of Contents

Proven Reasons Why Tea Does Not Dehydrate You

Tea is the second most popular beverage in the world. On any random day in the United States, more than half of Americans drink tea in hot or iced form, equating to 3.8 billion gallons per year.1

Tea does contain caffeine in varying amounts. Caffeine is a mild diuretic, meaning it can cause more urine output. This leads many people to wonder if their daily tea intake is helping or hurting their hydration status.


Why is Hydration So Important?

Hydration is critical for the proper function of the body. You can meet some of your fluid intake through the foods consumed, but extra fluid intake is required to meet your daily needs. Sixty percent of a person’s body weight is water. The body monitors water balance carefully, and even slight alterations lead to negative effects.2

A reduction of 1 or 2 percent of body water is considered mild dehydration causing impaired cognitive functions, alertness, concentration, short-term memory, and the ability to exercise.  

Further reduction in fluid status leads to the inability to manage body temperature, causing heat injury and urinary or kidney issues like kidney stones. Severe effects would include seizures and shock due to inadequate fluid in the body.2

Hydration is essential for survival and optimum performance. 

Tea Nutrition Facts 

Tea is not only a source of hydration but offers various nutritious benefits. Tea has no calories and trace amounts of vitamins, minerals, proteins, fats, and carbohydrates. 

Tea is also an excellent source of polyphenols. Polyphenols are beneficial compounds found naturally in different foods and drinks that act as antioxidants by neutralizing compounds called free radicals that lead to inflammation and disease in the body.3 

The most studied and predominant polyphenols in tea include catechins (from green tea), theaflavins, and thearubigins (from black tea). These polyphenols have been found to prevent cancer, diabetes, and cardiovascular and neurological diseases.3

Can Tea Dehydrate You?

The rationale behind the thought that tea can cause dehydration is related to the caffeine content. Solid evidence to support this theory is limited. Caffeine is considered a mild diuretic, but recent research reveals that this dehydrating effect is linked to high intakes of caffeine.4 

Let’s look at how your body is affected by caffeine and the approximate amounts of caffeine in tea. 

Caffeine is found in beverages like tea, soda, coffee, and chocolate. Foods and drinks with caffeine are digested in the gastrointestinal tract, and the caffeine is quickly transferred to the bloodstream, the liver, and the whole body.5

Caffeine boosts alertness and mood, has antioxidant and anti-inflammatory actions, and enhances athletic performance.5 The possible drawback is the extra elimination of fluid from the kidneys. But how much caffeine is required for this effect, and how much does this impact dehydration?

Recent research among individuals consuming varying levels of caffeine found that it takes a lot of caffeine to cause dehydration. Caffeine intake in the amounts of 250 to 300mg (comparable to 5 to 8 cups of tea or 2 to 3 cups of coffee) does cause short-term increased urine output in individuals deprived of caffeine. Interestingly, people consuming caffeine daily develop a tolerance and have minimal diuretic effects.4 

The concept of moderation applies to caffeine, as with many food and beverage choices. Overconsumption is the most significant factor for dehydration. 

Another study found similar results when comparing the intake of 1 liter of an assigned beverage intake. Thirteen beverages, including iced tea, coffee, hot tea, soda, and sports drinks, were compared to water and their respective urine outputs in the four hours following consumption. Urine output after drinking tea was similar to that observed after drinking water. This study was completed on 72 males with no significant health conditions. Hydration status is less stable in individuals with heart or kidney issues and young children or the elderly.6 

Caffeine-containing beverages like tea can be an appealing and beneficial fluid source for many people. As you peruse this list, note how many are relatively low in caffeine, allowing them to provide adequate hydration. 


Different Types of Teas = Different Hydration Levels 

Caffeinated teas

The four main varieties of caffeinated teas include black, green, white, and oolong. All four contain similar amounts of caffeine and come from the same plant. They are processed differently, resulting in different flavors and polyphenols.7,8 

Black tea

This stand-by contains 17.73 mg of caffeine per g of tea.7 Most commercially available tea bags contain 1.5 to 2 g of black tea. This would equate to about 30 mg of caffeine per cup of tea. 

Remember that the longer a cup is brewed, the higher the caffeine content.7 If you are in the habit of steeping the tea the entire time you drink it, you consume more caffeine. Steep time for black teas is generally around three to five minutes.

Green tea

Green tea is gaining popularity due to its health benefits. This tea contains 16.28 mg of caffeine per g of tea, equating to about 28 mg per cup of tea.7 

White tea

White tea is minimally processed and contains 16.79 mg of caffeine per g of tea, equating to about 29 mg of caffeine per cup.7 

Oolong tea

Oolong tea is a partially oxidized tea, making it an intermediate between the full oxidation process for black tea. This range of processing causes the different flavors and levels of polyphenols. Oolong tea contains 19.31 mg of caffeine per g of tea, equating to about 34 mg per cup of tea.7 

Herbal teas

Herbal teas are often called herbal infusions since they are not made with tea leaves. They are typically a blend of flowers, herbs, spices, or dried fruit and can be purchased in tea bags or loose forms. Herbal teas are brewed similarly to tea, and some popular varieties include chamomile, peppermint, lemon, ginger, and lavender. 

Due to the absence of tea leaves, herbal teas are usually caffeine-free. As a result, herbal teas or infusions do not have any dehydration effects. 

<p class="pro-tip"><strong>Check out this article for</strong> <a href="/blog/benefits-of-lemon-ginger-tea">Benefits of Lemon Ginger Tea: Nutrition Facts and Why You Need It</a>.</p>

Hybrid varieties

You can buy mixtures of caffeinated and herbal teas for a delightful blend of flavors. Green tea is often mixed with herbal varieties like peppermint or lemon ginger. These teas generally contain less caffeine than the caffeinated versions. 

Decaffeinated teas

Decaffeinated teas, by law, must have less than 2.5 percent of their original caffeine content.10 In general, most decaffeinated teas have 2 to 12 mg of caffeine per cup.11 

Remember that the steep time does increase the caffeine content. You would have to drink a lot of decaffeinated tea to reach the threshold of 250 to 300 mg of caffeine to impact your fluid balance negatively. 

Is Drinking Tea the Same as Drinking Water? 

While drinking tea is not the same as drinking plain water, it can be a beneficial and hydrating option to meet your daily fluid needs. Ensuring you are hydrated helps regulate body temperature, physical performance, cognitive abilities, and healthy body systems.12 

Meeting your daily fluid needs solely with tea could lead to excessive caffeine intake, depending on type and brew time. One would have to drink at least 10 cups or 80 ounces of black tea to reach 300 mg of caffeine. Unlike water, unsweetened tea also contains many polyphenols known for their role in preventing diseases like cancer and cardiovascular disease.8 

Tea vs. Coffee: Which One is Better for Hydration? 

One cup of tea is about 30 mg of caffeine, whereas one cup of coffee is about 95 mg of caffeine.7 High caffeine intake is associated with dehydration. 

Tea is more hydrating as it would take significantly more tea to achieve a high caffeine intake. You can also choose decaffeinated or herbal teas to reduce caffeine intake and improve hydration. 


Health Benefits of Tea (Beyond Hydration) 

Teas originate from the same Camellia sinensis plant, but their drying and final processing determine whether they are categorized as green, black, oolong, or white tea.7 This explains why all teas exhibit promising health benefits.

Green tea is shown to be cancer-preventive in animal and human studies based on data from an extensive summary review of research.8 Additionally, black tea may work in similar ways. Skin, prostate, lung, and breast cancer are shown to be decreased in those consuming black and green teas. Drinking 10 cups of green tea reduced the risk of lung, colon, and liver cancers.8 

Enhanced cardiovascular and metabolic health is correlated with tea consumption. Green tea increases antioxidant activity in the body, reducing inflammation related to chronic diseases. Green tea has also been found to reduce the absorption of triglycerides and cholesterol within the body, lessening arterial plaque build-up.8 

Data from eighteen studies indicated that higher intakes of coffee, decaffeinated coffee, and tea are linked to a reduced risk of diabetes.13 One study, in particular, found that people consuming more than three or four cups of tea per day had a one-fifth lower risk of diabetes than non-tea drinkers.13

This makes you want to brew a cup of tea right now to start accumulating your health benefits.

Six Tips to Enjoy Tea 

  • Plain iced or hot tea is the healthiest option
  • Skip or limit added sweeteners like sugar, honey, or agave nectar
  • Consider adding natural flavors with citrus fruits like lemon or orange
  • Brew a large batch and keep it in your fridge for an easy and refreshing drink
  • Check labels for added sugar when reaching for bottled iced tea 
  • Mix herbal teas with green teas for a hydrating spin on your usual tea

The Bottom Line

Signos recommends incorporating unsweetened tea varieties into your daily routine. Balancing your tea intake with several cups of water throughout the day should allow you to achieve proper hydration and minimal diuretic effects on the body. Choosing a variety of hydrating beverages like teas, unsweetened flavored water, and water can ensure you are meeting your daily fluid needs.

Learn More About How to Enhance Your Health with Signos.

Using a Signos’ CGM can help you adopt healthy habits while monitoring how your body reacts to food and beverages like tea. 

The CGM and Signos will give you tailored recommendations to optimize your metabolic health.

Take a quick quiz to determine if Signos is a good fit for you. You can learn more about how Signos works

<p class="pro-tip"><strong>Read more:</strong> <a href="/blog/weight-loss-coffee">Can Green Coffee Help You Lose Weight?</a>.</p>

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About the author

Sarah Bullard is a registered dietitian and nutrition writer with a master’s degree in nutrition. She has a background in research and clinical nutrition, personalized nutrition counseling, and nutrition education.

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