Return to T Ching Classics: Cold Brew Tea
Cold brewing can be done with both tea and coffee. Some people find cold brewing to be superior because of the exceptionally smooth flavor and a noticeable lack of tannins.
We’ve written previously about cold brewing versus hot brewing when it comes to caffeine. However, what about the health benefits? In general, when you cold brew tea you are trading heat for time. We’ve looked at a number of reputable studies and found that cold brewing tea offers the same level of health benefits versus hot brewing. To be specific, we are referring to pure tea and the anti-oxidants released during the cold brewing process.
How much tea should you use when cold brewing? At our cafe, we use 2 level tablespoons of tea per 18 ounces of water for hot tea. Each tea is different, and you may notice that certain teas such as the tightly rolled green and oolong teas require less tea than other types, so you’ll need to play with the amounts to find out what works best. For cold brewing, we use the same proportions, and sometimes add just a little more tea to the mix.
However, there are no set rules and you need to feel it out based on the type of tea and volume you are brewing. One thing is for certain: cold brewing is a little more forgiving if you use too much, as cold brewing will not become bitter from over steeping. One other tip is to agitate the leaves at some point during the cold brewing process.
An area where you may opt not to cold brew is certain herbal and fruit tisanes. Some herbal blends contain roots (i.e. ginger or turmeric for example) which have certain compounds that need hot water in order to be released. Boiling water may also pull out some additional flavor from dried fruits and berries. Leafy herbs like peppermint should be fine, however. There are some herbal blends that recommend boiling water for a ‘safe cup’. Although unlikely it is possible some herbal or fruit blends with a lot of “stuff” in them may have some microbes, so using boiling water is effectively pasteurizing the tea.
As far as equipment is concerned, using a dedicated cold brewer, like the For Life Mist series makes life easier. You can simply throw the tea in the pitcher and not have to worry about bags.
What is the maximum amount of tea you can drink?
Tea contains caffeine, like coffee. However amino acids like l-theanine in tea cause the caffeine to be absorbed more slowly. There is also less caffeine in tea because you need less tea in dry weight terms to make a cup of tea versus coffee. Because of lower caffeine content, you can drink more tea per day than coffee without going into what is considered a danger zone (i.e. 600 milligrams of caffeine per day). We’ve reviewed many studies over the years and found that the sweet spot for tea is 5-6 cups per day all the way up to 10 cups. This translates into 40-80 ounces of tea per day. None of the studies we’ve looked at exceeded this amount. Black tea probably tops out at 45mg per 8 ounces. Even if you drank 10 cups of black tea you will not exceed the caffeine limit.
How Much Fluid?
The old rule of thumb about drinking 8 glasses of water (64 ounces) no longer applies. Instead, they focus on fluid content as a whole, which includes fluids in food. The new general recommendation is 91 ounces total fluid intake for women and 125 ounces for men. Generally speaking, we get about 20% of our water directly from food. If you eat a lot of salad you’ll get a lot more water than you would in a Bic Mac.
Beverage Hydration Index
A recent study created the so-called Beverage Hydration index, ranking various beverages in their ability to rehydrate. It was no surprise that tea is at the same level of water (100%). Caffeine does have diuretic properties, which is why coffee scores a little below tea. But what is interesting is that the body becomes tolerant of the diuretic properties of caffeine with regular intake. Previous studies focused on high coffee intake (over 300mg) to individuals DEPRIVED of caffeine for a period of days or weeks.
Too much tea…..??
Depending on how you measure your cup (6 ounce traditional tea cup size or the 8 ounce size), you can drink a lot of tea per day (in most cases a healthy 64 ounces) and not have any ill effects. But can you overdo it? There are cases where drinking too much tea, or too much of a particular type of tea can be harmful.
We looked at a few worse case scenarios. One person died from kidney failure caused by excessive black tea consumption. In this case, the individual consumed about one gallon (128 ounces) of black tea a day. That’s all day, every day. Black tea contains oxalates, which is found in various vegetables and is found in black tea. Another person developed flourosis by consuming too much tea. In this case she had an iced tea habit made every day from 100-150 tea bags. Mass market bagged tea also contain more fluoride than their loose leaf counter parts.
Extreme amounts of tea, or any nutrient for that matter can have damaging effects . Water, even in extreme quantity can kill you. Based on the various studies, 64 ounces of tea is probably an ideal maximum for most people without any other dietary issues. We would also recommend changing tea types – not focusing on one type of tea.
Photo “Iced Tea” is copyright under Creative Commons Attribution 2.0 Generic License to the photographer Pen Waggener and is being posted unaltered (source)
I can’t thank you enough for all your research on this topic. So important to know. I hadn’t even heard about the Hydration index but I think it’s quite helpful in understanding our bodies mechanisms. People need to be aware that one can over do anything that is good for us – exercise, sauna, food, sleep, WATER and tea. I appreciate the reminder.
A lot of people think that if its good for you – taking a lot of it must be better. Sadly our bodies don’t work like that.
Has anyone yet entered cold-brewed tea into iced tea championships?
This was very interesting and I think I need to cut down a bit on my tea addiction I take 16 cups of tea daily (if not more) Thanks for this great post
It also depends on the type of tea you drink. Bagged tea will contain alot more contaminants and fluoride. If you are measuring cups by 8 ounces, then 16 cups is 128 ounces. That’s a lot of fluid. At the very least make sure the tea is organic and do your research. There are a lot of variables with nutrition, so studies are notoriously difficult to quantify.
Well I’m not really sure about the US measurements as I’m from europe I do believe it is a lot of tea that you would drink. The amount is probably only correct if you would keep tossing your tea after 1 steeping.
Some days I’ll drink about 2 a 3 liters of tea but that will be all the same leaves re-brewed many times so I’ve not noticed any health issues other than having to visit the toilet more often.
In this article, you refer to a man who “died from kidney failure caused by excessive black tea consumption.” and include a link to the cited NEJM article. Unfortunately, that article had three key oversights that led to the authors incorrect conclusion that black tea was causal. I have previously shared these oversights with the NEJM when the article was published in 2015.
• The first oversight is that the authors inadvertently assumed that “iced tea” provides enough information to make a valid conclusion. Without knowing the type of tea consumed – black, green, white, oolong or dark tea – it is impossible to accurately assess its composition. Similarly, it is essential to know if the iced tea was instant, powdered or steeped. For a complete assessment, it is also necessary to be aware of the water source – well, city, purified, etc.
• There are profound inaccuracies in the evidence the authors cited to support their claim that tea contributed to the patient’s nephropathy. The data that is referenced from the British Journal of Nutrition article dates back to 1962, but actually provides oxalate values from 1933 and 1939. Since the initial publication, the methodology employed to determine these values has been scrutinized and criticized. As stated in the 1962 BJN article, “Several extensive studies of the oxalate content of foods have been made within recent years, but the accuracy of the analytical procedures is sometimes open to question. The method employed by Kohman (1939) was criticized by Andrews & Viser (1951), who considered that recovery of oxalic acid was incomplete.”
• In the letter, additional references are provided for statements made about tea and oxalates. These too have errors. Urology is cited to support the statement: “Black tea is a rich source of oxalate, containing 50 to 100 mg per 100 ml, a level that is similar to or higher than that in many foods considered to be rich in oxalate.” After careful review of the Urology article, there is no such reference to tea and the article instead discusses the oxalate values in foods. The same can be said for their statement, “The average daily intake of oxalate in the United States is 152 to 511 mg per day, which is higher than that recommended by the Academy of Nutrition and Dietetics (<40 to 50 mg per day)." The first statement regarding average daily intake was taken from a different article that speaks of specific oxalate values in foods, not specifically to tea. And, the recommendations to which the authors refer in the Academy of Nutrition and Dietetics are taken from their position paper regarding patients with known kidney stones. This does not apply to the patient discussed in the letter.
I fully agree with you that everything should be taken in moderation, however, the linkage of tea (Camellia sinensis) to ANY human death is not supported by any published source.
Position Statement: Fluoride in Tea Does Not Pose a Health Risk
The Dietary Reference Intake’s Upper Intake Level set by the Institute of Medicine for fluoride is 10 mg/day for teenagers and adults, 2.2 mg/day for kids aged 4-8 years and 1.3 mg/day for ages 1-3.1 Based on the amount of fluoride found in commonly consumed tea beverages (e.g., ready-to-drink, instant powdered and brewed black tea) along with the current tea intake levels in the U.S., the fluoride in tea does not pose a health risk to Americans consuming tea.
Fluoride is an element that is found naturally in some community water systems, and is added to water in other areas around the world to reduce dental decay. The levels recommended in the Dietary Reference Intakes (DRIs) set by the Institute of Medicine (IOM) have been shown to reduce tooth decay without causing marked fluorosis – a discoloration of the teeth that could occur in children who use dental products with fluoride in addition to fluoridated water.1 As with other vitamins and minerals, amounts consumed in excess of what is required by the body can have adverse health effects. If over consumed, fluoride can build up in the bone and lead to skeletal fluorosis. Because of this, the IOM has set the Upper Limit for fluoride at 10 mg/day.1
Fluoride can be found naturally or added to drinking water. To protect against over consumption, the U.S. Environmental Protection Agency (EPA) has set a maximum amount of fluoride allowable in drinking water of 4.0 mg per liter. According to a six-year review of U.S. EPA drinking water regulations and the intake data from the U.S. Department of Agriculture (USDA) Continuing Survey of Food Intake by Individuals (CSFII), the average fluoride level in public drinking water systems is ~0.87 mg/L.2
Currently, exposures to fluoride come from drinking water, foods, beverages, dental products (toothpaste, mouth rinses), supplements, industrial emissions, pharmaceuticals, and pesticides.2
Fluoride in Tea
Based on the U.S. Department of Agriculture (USDA) National Nutrient Database for Standard Reference, the amount of fluoride in commonly consumed tea beverages is:3
Black tea, brewed with tap water
8 oz. (1 cup)
Ready-to-drink, iced tea with lemon flavor
12 oz. can
Instant tea, unsweetened powder, prepared with tap water
8 oz. (1 cup)
Tea Consumption in the U.S.
The U.S. mean tea intake among men and women aged 20 and over is 0.9 cups per day.4 This includes tea and tea-based drinks, such as ready-to-drink sweet tea and tea made from presweetened mix. It is estimated that for children aged 4-13 years, tea accounts for only 36.7 ml of total water consumption according to NHANES 2005-2010.5
Excess Fluoride Intake from Tea
Over the past 20 years in the U.S., four case reports have been published attributing skeletal fluorosis to excessive tea consumption – with one individual consuming high amounts of fluoridated toothpaste in addition to tea.6-9 In each situation, the study authors described the patient’s behavior as obsessive-compulsive drinking and warn against habitual consumption of large volumes of extra strength instant or brewed tea. The amount of tea consumed in one case was 1-2 gallons of brewed orange pekoe tea for more than three decades; in another case, a 52-year old woman consumed 1-2 gallons of double-strength instant tea daily since she was 12 years old. As with excessive, chronic over-consumption of any one food or beverage, nutrient toxicity should be a concern.
Fluoride is found in most community water systems, as well as foods prepared with water that contains fluoride. It is also consumed in tea, gelatin and breast milk. Over consumption of fluoride from any food or beverage source, above the Upper Limit of 10 mg/day may pose a health risk. In the U.S., the amount of fluoride found in tea beverages in commonly consumed serving sizes ranges from 0.265 to 0.798 mg. The average tea consumption is 0.9 cups (7.2 oz.) per day3; therefore there is no concern for fluoride toxicity from healthy tea consumption in the U.S.
1. Dietary Reference Intakes for Calcium, Phosphorous, Magnesium, Vitamin D, and Fluoride. 1997. Accessed from: http://www.nap.edu
2. Fluoride: Exposure and Relative Source Contribution Analysis. Health and Ecological Criteria Division, Office of Water. U.S. Environmental Protection Agency. Washington, D.C. 2010.
3. USDA, Agriculture Research Services, National Agriculture Library, USDA National Nutrient Database for Standard Reference. Accessed from: http://ndb.nal.usda.gov/.
4. LaComb RP, Sebastian RS, Wilkinson Enns C, Goldman JD. Beverage Choices of U.S. Adults: What We Eat In America, NHANES 2007-2008. Food Surveys Research Group Dietary Data Brief No. 6. August 2011. Accessed from: http://ars.usda.gov/Services/docs.htm?docid=19476.
5. Drewnowski A, Rehm CD, Constant F. Water and beverage consumption among children age 4-13y in the United States: analyses of 2005–2010 NHANES data. Nutrition Journal. 2013; 12: 85. Available from: http://www.nutritionj.com/content/12/1/85.
6. Hallanger Johnson JE, Kearns AE, Doran PM, Khoo TK, Wermer RA. Fluoride-related bone disease associated with habitual tea consumption. Mayo Clin Proc. 2007 Jun;82(6):719-724.
7. Izuora K, Twombly JG, Whitford GM, Demertzis J, Pacifici R, Whyte MP. Skeletal fluorosis from brewed tea. J Clin Endocrinol Metab. 2011 Aug;96(8):2318-2324.
8. Whyte MP, Totty WG, Lim VT, Whitford GM. Skeletal fluorosis from instant tea. J Bone Miner Res. 2008 May;23(5):759-769.
9. Joshi S, Hlaing T, Whitford GM, Compston JE. Skeletal fluorosis due to excessive tea and toothpaste consumption. Osteoporos Int. 2011 Sep;22(9):2557-2560.
I am so grateful for the correction Peter. I wish the link was removed so that people didn’t keep referring to it.
I should have noted, that the article should not be taken as ‘clinical proof’ that excessive black tea consumption killed the individual. There are so many variables that aren’t discussed in the article. It was mainly for illustration purposes ‘too much of a good thing isn’t always good’.
I’m currently researching toxic metal and teas. The way some websites portray it, you should pretty much avoid all tea.
I’ll be more careful with the caveat…not to take a USA today article literally
We’ve all made similar mistakes Kevin. When we read something in a source we believe to be credible, we accept it as fact. Looking forward to reading about toxic metal and teas. I just had some labs come back with heavy metal toxicity – never even considered tea a possible culprit.