Tea has traditionally been associated with various mental benefits, such as relaxation or clarity of mind1. For instance, the story goes that Isaac Newton was drinking a cup of tea at the moment that he discovered the universal law of gravity. Until a decade ago, the alleged mental benefits of tea were solely based on anecdotal evidence. Recently however, scientists have started exploring the benefits of tea and its ingredients and discovered its beneficial effects on cognition and mood.

Black, oolong, green and white teas are all made from the leaves of Camellia sinensis, a plant cultivated in tropical and subtropical regions. The differences in colour and taste relate to processing, with green and white tea leaves undergoing less or no oxidation while black tea leaves are fully oxidised. Recently, there has been a growing interest in the effects of black tea and its ingredients on cognitive performance and mood.

Tea significantly contributes to body’s hydration status, which is critical for mental performance.

Proper hydration is essential for general health and well-being, but also for mental performance. Our brain being 75% water, it is no surprise that mental performance is affected by even mild dehydration. Studies show that poor hydration reduces concentration and alertness, adversely affects the ability to perform mental tasks2 and leads to deterioration of mood3.

Tea is the second most consumed drink worldwide, and has therefore the potential to boost fluid intakes, especially as its flavour is often preferred over water. Scientists also agree tea is a healthy form of hydration. A recent clinical trial looked at the impact of tea consumption on blood and urine markers of hydration4 and showed no significant differences between tea and water. Beverages guidance systems in different countries (US, UK, Italy) classify leaf tea as second ideal fluid choice for hydration after water, based on its calorie-free properties and health benefits5.

Mental Benefits of tea ingredients

Tea brews are a natural source of water, theanine and caffeine, ingredients which have all been shown to affect mental performance.

Tea contains low doses of caffeine, which increases attention and alertness

Caffeine is naturally found in a large variety of foods (e.g. coffee, tea, chocolate) and is the most widely consumed psychoactive ingredient6. A typical serving of black tea (200ml) naturally contains approximately 35 to 61mg caffeine, whereas green tea contains less caffeine (around 25 mg / 200 ml)7.

Over the last 20 years, a large number of studies have investigated the psychological effects of caffeine, and confirmed its general arousing and psychomotor effects (for review e.g. Smith, 20028). Numerous studies have identified effects of various caffeine doses, even those found in a cup of tea, on simple attention tests and alertness.

Caffeine and L-theanine in combination improve attention and alertness

As caffeine and L-theanine naturally co-occur in tea, several studies have investigated the attention effects of both ingredients in combination14-18. These studies showed that high doses of theanine (100 mg) combined with low doses of caffeine (50 mg) improve attention compared to a placebo, as measured by standardized computer attention tests, and increase feelings of alertness, as measured by self-report mood questionnaires.

Tea is a source of water, caffeine and L-theanine, ingredients that have been shown to have an effect on mental performance and mood. What about the effect of tea as whole on cognitive performance?

Water

Theanine

45 60 75 90 105 minutes after drink

+0.7+0.8+0.4+0.3+0.2+0.10

μV

Figure X: Measurement of brain activity with EEG (Electroencephalogram).

Our brain constantly emits electrical impulses, called brain waves. Five

different types of brain waves can be characterised with EEG by their

frequency and amplitude, and each type is dominant in a specific state, from

wakefulness to sleep. During rest, the so-called alpha waves are dominant

when being in an awake, relaxed state. Therefore, alpha waves are thought

to reflect physiological relaxation9

L-theanine, a unique tea ingredient, affects brain activity

L-theanine is an amino acid almost exclusively found in the tea plant. Brews of green tea and black tea will deliver between 4.5 mg and 22.5 mg theanine, depending upon the variety used, time of infusion, and amount of tea leaves used. To date, the effects of theanine have been studied in a number of EEG (electroencephalography) studies, which measure brain activity.

Figure X: Alpha wave activity in the brain as measured by EEG on a schematic top-view of the scalp, following L-theanine or

water ingestion. Alpha brain activity was higher after L-theanine than after water (p<0.05), as indicated by the red colour13

Mental clarity benefits of black tea

Black tea improves attention and feelings of alertness

The effects of tea on alertness were originally investigated in four studies comparing the effects of tea, with coffee and water19-21. It was demonstrated that having a few cups of tea during the day increased subjective alertness and helped sustain arousal throughout the day. Since then, more research has been conducted on the mental benefits of tea.

Two recently published Unilever studies have investigated the effects of commercially available black tea blends on attention22. In both studies, participants performed more accurately on attention tests and reported feeling more alert after drinking black tea. These results have been replicated in a third unpublished study.

Black tea consumption helps sustain work performance

Studies show that tea consumption can prevent the natural decrement in arousal during the day19,20, and improves the ability to focus attention22. These findings suggest regular tea consumption may help sustain work performance.

The relationship between beverage (tea, coffee and other beverages) consumption and associates of work performance and mood was recently investigated in a relatively stressful and cognitively demanding work-place setting (Bryan et

al, unpublished). Participants were 95 professional and academic staff members of three South Australian Universities, who recorded their beverage intake and levels of work performance, engagement, fatigue, mindfulness, mood, work-related strain and recovery for 10 working days. Results showed that tea consumption was associated with increased perceived work performance and reduced tiredness, especially when consumed without milk or sugar. These promising first results need to be further investigated.

These studies indicate that 2 to 3 cups of black tea consumption improves the ability to focus attention and feelings of alertness. The tea ingredients caffeine and theanine are thought to be responsible for these cognitive benefits.

Time for a (tea) break?

It is generally acknowledged that taking regular breaks in a day allows getting more focused and productive. This is especially important during working days when attention has to be maintained for several hours. Studies investigating the effects of rest breaks on work productivity report that increase in rest break frequency either result in higher work productivity23-25 or do not affect productivity26-29. The absence of significant productivity loss with supplementary breaks is noteworthy, as this means that performance is not impaired in spite of the reductions in work time necessitated by the extra break.

Tea breaks combine the cognitive benefits of tea with the recreational and rejuvenating functions of rest breaks, and can play a role in sustaining work performance throughout the day.

Early evidence for the relaxing benefits of tea

Tea consumption is often associated with relaxation and stress alleviation. Taking regular tea breaks is a common way to unwind and relax within a day. Only few studies have investigated the effects of tea and tea ingredients on relaxation and stress. As already mentioned, L-theanine, an amino acid almost exclusively found in the tea plant, has been shown in several studies to improve alpha brain activity at rest, which is indicative of (physiological) relaxation.

One study investigated the effects of 6 weeks of black tea consumption, compared with matched placebo, on subjective, cardiovascular, cortisol (‘stress hormone’) and platelet responses to acute stress. Long-term black tea consumption decreased cortisol levels 50 min following a stress task, and increased subjective relaxation in the post task recovery period30. Although the evidence is very limited, this study suggests black tea consumption can help with stress relief and relaxation.

Tea has historically been perceived as a refreshing and calming beverage, associated with relaxing, unwinding and mental clarity benefits. Only recently have studies begun to investigate these effects, giving scientific grounds behind tea mental benefits. Consistent evidence shows that black tea improves the ability to focus attention and increase alertness. The tea ingredients theanine and caffeine have been associated with these cognitive benefits. Emerging evidence also suggests beneficial effects of tea, especially in the context of a break, for sustaining work performance and relaxation.

10 reasons for drinking tea throughout the day

1) Hydrating: Tea is hydrating and ranked as 2nd ideal fluid choice for hydration after water5

2) Delicious: Black, green, oolong, white, flavoured….. Vary the colour, vary the pleasure, stay hydrated!

3) Calorie-free: Tea is 0 calorie* and therefore a healthier fluid choice than calorific drinks

4) Healthy: Tea consumption is associated with health benefits, in particular for cardiovascular health31,32

5) Low in caffeine: Tea contains low doses of caffeine, but enough to increase alertness!21

6) Help you stay focused: Scientific studies show black tea, such as LYL, improves concentration22

7) Keep you going: Regular tea consumption prevents performance decrements throughout the day19

8) Take a break: Regular rest breaks can improve work productivity23

9) Relax: Tea breaks are an enjoyable time to relax and unwind

10) Enjoy: Socialise with your friends or colleagues around your favourite cup of tea!

References1- Shimbo, M., Nakamura, K., Jing, S.H., Kizuki, M., Seino, K.,

Inose, T., and Takano, T. (2005). Green tea consumption in everyday life and mental health. Public Health Nutrition, 8, 1300-1306.

2- Ritz P & Berrut G (2005) The importance of good hydration for day-to-day health. Nutrition Reviews 63 (Part II), S6–13

3- D’anci KE et al (2009) Voluntary dehydration and cognitive performance in trained college athletes. Perceptual and Motor Skills 109, 251-69

4- Ruxton CH, Hart VA. Black tea is not significantly different from water in the maintenance of normal hydration in human subjects: results from a randomised controlled trialBr J Nutr. 2011 Aug;106(4):588-95

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8- Smith, A. (2002). Effects of caffeine on human behaviour. Food and Chemical Toxicology, 40, 1243-1255.

9- Cahn, B.R., & Polich, J. (2006). Meditation States and Traits: EEG, ERP, and Neuroimaging Studies. Psychological bulletin, 132 (2), 180–211.

10- Juneja, L.R., Chu, D.C., Okubi, T., Nagato, Y., and Yokogoshi, H. (1999). L-theanine - a unique amino acid of green tea and its relaxation effect in humans. Trends in Food Science & Technology, 10, 199-204.

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14- Rogers, P.J., Smith, J.E., Heatherley, S.V., and Pleydell-Pearce, C.W. (2008). Time for tea: mood, blood pressure and cognitive performance effects of caffeine and theanine administered alone and together. Psychopharmacology (Berl), 195, 569-577

15- Haskell, C.F., Kennedy, D.O., Milne, A.L., Wesnes, K.A., and Scholey, A.B. (2008). The effects of l-theanine, caffeine and their combination on cognition and mood. Biological Psychology, 77, 113-122.

16- Owen G.N., Parnell H., De Bruin E.A., & Rycroft J.A. (2008). The Combined effects of L-theanine and caffeine on cognitive performance and mood. Nutritional Neuroscience, 11,4, 193-198.

17- Einöther, S.J.L., Martens, V.E.G., Rycroft, J.A., & De Bruin, E.A. (2010). L-theanine and caffeine improve task switching but not intersensory attention or subjective alertness. Appetite, 54, 406–409.

18- Giesbrecht, T., Rycroft, J. A., Rowson, M. J., & de Bruin, E. A. (2010). The combination of L-theanine and caffeine improves cognitive performance and increases subjective alertness. Nutritional Neuroscience, 13, 283-290.

19- Hindmarch, I., Quinlan, P. T., Moore, K. L., & Parkin, C. (1998). The effects of black tea and other beverages on aspects of cognition and psychomotor performance. Psychopharmacol, 139, 230-238.

20- Hindmarch, I., Rigney, U., Stanley, N., Quinlan, P., Rycroft, J., & Lane, J. (2000). A naturalistic investigation of the effects of day-long consumption of tea, coffee and water on alertness, sleep onset and sleep quality. Psychopharmacology, 149, 203-216.

21- Quinlan P. T., Lane J., Moore K. L., Aspen J., Rycroft J. A. & O’Brien D. C. (2000). The acute physiological and mood effects of tea and coffee: the role of caffeine level. Pharmacology, Biochemistry and Behaviour, 66, 19-28.

22- De Bruin, E.A., Rowson, M.J., Van Buren, L., Rycroft, J.A., & Owen, G.N. (2011). Black tea improves attention and self-reported alertness. Appetite, 56, 235-240.

23- Henning, R.A., Jacques, P., Kissel, G.V., Sullivan, A.B., & Alteras-Webb, S.M. (1997). Frequent, short breaks from computer work: effects on productivity and well-being at two field sites. Ergonomics, 40 (1), 78-91.

24- Kopardekar P and Mital A. The effect of different work-rest schedules on fatigue and performance of a simulated directory assistance operator’s task. Ergonomics. 1994 Oct;37(10):1697-707

25- Van den Heuvel SG, De Looze MP, Hilsebrandt VH, the KH.

effects of software programs stimulating regular breaks and exercises on work-related neck and upper-limb dosirders. Scand J work Environ Health 2003; 29(2):106-116.

26- Galinsky T, Swanson N, Sauter S, Dunkin R, Hurrell J. Schleifer L. A field study of supplementary rest greaks for data-entry operators. Ergonomics 2000 May; 43(5):622-38

27- Galinsky T, Swanson N, Sauter S, Dunkin R, Hurrell J. Schleifer L. Supplementary breaks and stretching exercises for data entry operators: A follow-up study. American Journal of industrial medicine 50, 519-527 (2007).

28- Dababneh AJ, Swanson N, Shell RL. Impact of added rest breaks on the productivity and well being of workers. Ergi onomics 2001 Feb 10, 44(2):164-74

29- Mclean L, Tingley M, Scott RN, Rickards J. Computer terminal work and the benefit of microbreaks.Appl Ergon 2001, Jun; 32(3); 225-37.

30- Steptoe A, Gibson EL, Vounonvirta R, Williams ED, Hamer M, Rycroft JA, Erusalimsky D, Wardle J. The effects of tea on psychophysiological stress responsivity and post-stress recovery: a randomised double-blind trial. Psychopharmacology (Berl). 2007, 190(1):81-9.

31- Peters U et al (2001) Does tea affect cardiovascular disease? A meta-analysis, American Journal of Epidemiology 154, 495–503.

32- Hodgson JM & Croft KD (2010) Tea flavonoids and cardiovascular health. Molecular Aspects of Medicine 31, 495-502.

liptoninstituteoftea.org

Published November 2011All information correct at time

of going to press

Information for healthcare professionals