Caffeine and L-theanine: a combination for calm energy

Caffeine and theanine are probably one of the most extensively studied combinations of naturally derived supplements in the world. Caffeine stimulates the central nervous system, while L-theanine—an amino acid found in green tea—promotes calm alertness without drowsiness. Together, these two compounds produce a synergistic effect that researchers have called “calm energy”.

How do caffeine and theanine work together?

Caffeine works primarily by blocking adenosine receptors in the brain. Adenosine gradually builds up while you are awake and makes you feel tired—caffeine blocks its receptors, reducing fatigue and increasing alertness. Caffeine also stimulates the release of dopamine and noradrenaline, which improve mood and motivation.

L-theanine works through a different mechanism. This amino acid increases levels of GABA (gamma-aminobutyric acid) in the brain and stimulates alpha brainwave activity—a state associated with relaxed alertness and creative thinking, without causing drowsiness.

In a double-blind, placebo-controlled study (n=24), Haskell et al. (2008) found that the combination of caffeine and theanine improved attention, reaction speed and working memory significantly more than either substance alone (Haskell et al., 2008). Owen et al. (2008) confirmed that the combination also reduced subjective feelings of anxiety and increased calm attentiveness compared with caffeine alone (Owen et al., 2008).

What is the optimal dose, and how should you take the combination?

Most clinical studies have used a 1:2 ratio (caffeine:theanine)—the most common protocol is 100 mg of caffeine and 200 mg of theanine. Giesbrecht et al. (2010) showed that this specific combination produced statistically significant improvements in task switching and subjective alertness compared with a placebo (Giesbrecht et al., 2010).

The energy… boost from this combination is steadier and lasts longer than with caffeine alone, as theanine smooths out caffeine’s rapid “rush” and reduces the subsequent energy crash. EFSA has assessed single doses of up to 200 mg of caffeine as safe for the adult population, raising no safety concerns (EFSA NDA Panel, 2015).

The recommended time to take the combination is 30–60 minutes before mental exertion, studying or a workout. You should avoid taking it in the afternoon, given caffeine’s long half-life (5–7 hours).

Is the combination of caffeine and theanine suitable for athletes?

Caffeine before a workout is one of the most extensively studied ergogenic aids, improving both endurance and strength performance. The combination of caffeine and theanine adds a cognitive dimension—this may be particularly useful in tactical sports, where quick decision-making is crucial.

Einöther et al. (2010) found that the combination improved task-switching speed compared with a placebo, suggesting better executive function (Einöther et al., 2010). If you are an athlete interested in combinations aimed at strength and explosive power, you can also read the article CREATINE, CAFFEINE, which explores an entirely different mechanism of action.

Is the combination of caffeine and theanine safe, and what are the side effects?

Dodd et al. (2015) specifically investigated the combination’s effects on cardiovascular parameters and found that it did not increase blood pressure or heart rate significantly more than a placebo (Dodd et al., 2015). This is an important finding, given that caffeine alone is sometimes associated with heart palpitations.

L-theanine is generally well tolerated, and side effects are rare and mild. However, you should keep the following precautions in mind:

• If you are pregnant or breastfeeding, you should limit your caffeine intake and consult a doctor before using supplements.
• If you are under 18, you should not use supplements containing stimulants without a doctor’s recommendation.
• If you have trouble sleeping, avoid taking the combination in the afternoon—caffeine’s effects can last up to 10 hours.

Long-term use of caffeine-based products can lead to dependence and tolerance. Clinical studies have found no potential for dependence with theanine on its own.

References

• Haskell CF, Kennedy DO, Milne AL, Wesnes KA, Scholey AB. (2008). The effects of L-theanine, caffeine and their combination on cognition and mood. Biological Psychology, 77(2):113–22. PMID: 18006208
• Owen GN, Parnell H, De Bruin EA, Rycroft JA. (2008). The combined effects of L-theanine and caffeine on cognitive performance and mood. Nutritional Neuroscience, 11(4):193–8. PMID: 18681988
• Giesbrecht T, Rycroft JA, Rowson MJ, De Bruin EA. (2010). The combination of L-theanine and caffeine improves cognitive performance and increases subjective alertness. Nutritional Neuroscience, 13(6):283–90. PMID: 21040626
• Dodd FL, Kennedy DO, Riby LM, Haskell-Ramsay CF. (2015). A double-blind, placebo-controlled investigation of the effects of caffeine and L-theanine alone and in combination on cardiovascular parameters. Human Psychopharmacology, 30(4):267–79. PMID: 25761837
• Einöther SJ, Martens VE, Rycroft JA, De Bruin EA. (2010). L-theanine and caffeine improve task switching but not intersensory attention or subjective alertness. Appetite, 54(2):406–9. PMID: 20079786
• EFSA NDA Panel. (2015). Scientific Opinion on the safety of caffeine. EFSA Journal, 13(5):4102. DOI: 10.2903/j.efsa.2015.4102

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