Several times I heard comments like: avoid coffee, black tea, mate,… And, whenever I asked why, the ready answer was: “because of the caffeine!” And two questions came to my mind: what's so bad about caffeine? And most importantly, do you really know how much caffeine is in a cup of tea?
Let's start by answering the first question. What is caffeine and what are its controversies. Caffeine is an alkaloid from the xanthine group present in some plants and which protects them from insect attack. In relation to human consumption it can be an elixir or a poison. And what defines what role caffeine will play in the body is the dose consumed. According to experts, the daily dose of caffeine should not exceed 300-500 mg a day for adults and 100 mg a day for teenagers. Within these limits, caffeine brings several benefits since it is a natural stimulant, which keeps our brain in a state of alert, focused, fighting mental fatigue, giving more physical disposition. Caffeine also has thermogenic effects that help with weight loss. Another well-known effect of caffeine is to cause the pulmonary bronchi to dilate, thus optimizing breathing capacity. Moderate consumption can even prevent heart disease.
However, for people who are very sensitive or who consume above the recommended dose, adverse effects include anxiety, headache, insomnia, gastric discomfort, irritability and even high blood pressure. In very high doses, above 5 grams, caffeine can even lead to death.
As we have seen here, the benefits and harms depend mainly on the dose. So how much caffeine is in a cup of tea? Let's make a comparison with coffee, to be clearer:
-A cup of coffee (240ml) has 95 to 200mg of caffeine.
- A cup of black tea, which is the most caffeinated tea, can have anywhere from 14 to 70 mg of caffeine.
-If it's green tea, a cup can have 24 to 45 mg of caffeine.
– And if it’s iced tea, a cup can have 5 to 40 mg of caffeine.
In other words, it doesn't make much sense to put tea in the same basket as coffee when it comes to reduced/moderate caffeine consumption, since black or green tea has much less caffeine than coffee.
This comparison fails even more when completely disregarding a unique component of tea that interacts with caffeine, the all-important L-THEANINE.
L-theanine is an amino acid that makes up 1 to 2% of the weight of dried tea leaves. Caffeine constitutes only 0.5%, which makes l-theanine a more abundant and effective component than the caffeine in tea. Once ingested, caffeine is released into the bloodstream and reaches the brain, where it stimulates beta brain waves related to stressful or exciting situations. A few minutes after caffeine enters your nervous system, l-theanine is released by the small intestine and enters the bloodstream and, when it reaches the brain, stimulates alpha waves, related to alert and relaxed state, thus canceling out the stressful effects of caffeine. That is, focus, concentration remains, but without stress, heart rate acceleration, anxiety, etc. Therefore, the effect of caffeine present in tea is completely different from the effect of caffeine present in coffee or other beverages. Only tea, from camellia sinensis, has l-theanine.
L-theanine also plays an important role in the formation of gamma-aminobutyric acid, which acts on dopamine and serotonin receptors, producing a well-being and relaxation effect. This alert/relaxed effect provided by camellia sinensis alone is similar to what is desired in meditation. That's why tea has been the favorite drink of Chinese and Japanese monks for centuries.
So there's nothing to talk about caffeine in tea without considering the dose and the presence of l-theanine! You can have your tea calmly and let l-theanine do its thing!
REFERENCES:
Source: http://bluedogrevolution.com.br/site/2017/02/11/mitos-sobre-o-cha-cha-preto-a-cafeina-e-o-ingrediente-secreto/
Articles:
Crippa, A., 2014. Coffee consumption and mortality from all causes, cardiovascular disease and cancer: a dose response meta-analysis. American Journal of Epidemiology; August (2014) pii:kwu194.
Ludwig,I.,A., 2014. Variations in caffeine and chlorogenic acid contents of coffees: what we are drinking?. Food Funct; August (2014) 5(8):1718-26.
Zhang,C., 2014. Tea consumption and risk of cardiovascular outcomes and total mortality: a systematic review and meta-analysis of prospective observational studies. European Journal of Epidemiology; October (2014).
Books:
Americi,H; Desharnais, J.; Marchand, F.; Gascoyne, K., 2015. Green Tea. The quest for fresh leaf and timeless craft. Publisher Benjamin Press (Canada).
Spector, T., 2015. The diet myth. Publisher Alaude (Brazil).
Ukra,M., 2008. La diet del te. Publisher Cargraphics (Colombia).
Websites:
http://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-de
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