Are tannins in tea really so terrible?
Tea has to be by far one of the most popular beverages worldwide, but you may have heard some bad things about tea, namely about the tannins. Is the time up for tea, or are tannins not so terrible?
In this post, I am talking about tea made from the Camellia sinensis plant, so black tea, green tea, white tea, oolong tea, pu-erh tea, and purple tea - so many types of tea! But there are also considerable tannins in coffee, red wine and chocolate, so these should be considered too if you are thinking about tannins.
Tannins are what give tea its bitter flavour and dry mouthfeel, and they also contribute to the colour.
Generally black tea is highest in tannins and green tea lowest, but the concentration of tannins does vary a lot between teas, being generally higher in lower quality teas, and if the tea is steeped for longer.
So what is all the fuss about?
Well tannins are good at binding things, and this causes concern that tannins may impair some aspects of digestion.
The most worry in this regard is around tannins binding minerals especially iron, and therefore reducing how much iron in our digestive tract is available for absorption. Iron deficiency is actually a pretty common problem, and so consideration of anti-nutritional factors that may inhibit iron absorption is important. However, studies appear to show that tannins are not likely to cause a significant problem in those with healthy iron levels. And for anyone out there with low iron, the advice is to drink your tea between meals and also away from any iron supplements you may be taking so you avoid any interaction.
It is also worth being aware that tannins may be more able to block absorption of iron from plant-based foods compared to meat, so if you follow a vegan diet you may also want to be clever about meal and tea drinking timings.
Tannins can also be irritating to the digestive tract, especially on an empty stomach causing nausea or stomach ache. If this sounds like you, try to avoid drinking tea on an empty stomach, and if that does not work, perhaps tea is not for you!
But let’s not forget about the health benefits of tannins!
Tannins are often called ‘anti-nutrients’, which is really quite misleading because tannins actually have many health benefits! For example, tannins are anti-oxidants which means they protect your cells from damage from free radicals.
One of the main tannins in green tea is epigallocatechin gallate (EGCG). EGCG has been the subject of many studies and is thought to be behind many health benefits of green tea. For example, EGCG may reduce inflammation, act as an antioxidant, have anti-cancer properties (1) and cardiovascular protective properties (2). There is loads of ongoing research into the health benefits and therapeutic applications of EGCG!
Black tea is particularly high in theaflavins and thearubigins, two groups of tannin types. There is less research on these, but the research that has been done suggests they are powerful antioxidants protecting our cells from free radicals (3).
Tea also contains high levels of a tannin called ellagitannin which may be beneficial to keeping our microbiome happy (4) and may also have anti-cancer properties (5).
Of course there is more to consider than tannins when considering the interplay of tea with our health. For example, the caffeine in tea can help you be more alert and tea contains the amino acid L-theanine which may improve mental focus, increase relaxation and aid sleep! So there are other positives to drinking tea…. but then there are downsides for some people who are less able to metabolise the caffeine, such as anxiety, stress and restlessness as well as heart-burn and headaches.
So tea is actually quite a complex beverage when in comes to thinking about how it interacts with our health!
Tea is a really good example of why it is important to have a balanced view of the pros and cons of a particular food or beverage, and to not get overly caught up on just one aspect forgetting the rest.
Also, I hope the above demonstrates the importance of staying in tune with yourself and paying attention to how foods and drinks interact with your body. We are all unique, and what makes someone else feel great may not work for you.
Happy nourishment!
Fabia x
References
1. Ren-You Gan, Hua-Bin Li, Zhong-Quan Sui & Harold Corke (2018) Absorption, metabolism, anti-cancer effect and molecular targets of epigallocatechin gallate (EGCG): An updated review, Critical Reviews in Food Science and Nutrition, 58:6, 924-941
2. Swen Wolfram (2007) Effects of Green Tea and EGCG on Cardiovascular and Metabolic Health, Journal of the American College of Nutrition, 26:4, 373S-388S
3. Łuczaj W, Skrzydlewska E. Antioxidative properties of black tea. Prev Med. 2005 Jun;40(6):910-8.
4. Yang X, Tomás-Barberán FA. Tea Is a Significant Dietary Source of Ellagitannins and Ellagic Acid. J Agric Food Chem. 2019 May 15;67(19):5394-5404.
5. Ismail T, Calcabrini C, Diaz AR, Fimognari C, Turrini E, Catanzaro E, Akhtar S, Sestili P. Ellagitannins in Cancer Chemoprevention and Therapy. Toxins (Basel). 2016 May 13;8(5):151.
