Adding L-Theanine to Coffee Could Help You Stay Focused Without Jitters

A new “biohacking” trend is circulating online: adding 200 milligrams of L-theanine to your coffee. The combination is said to improve focus, provide consistent energy, and reduce caffeine-related crashes. Experts say there is some truth to these claims.

How does L-theanine affect concentration?

L-theanine, an amino acid found in green tea, affects chemicals in the brain that promote a state of calm and alertness rather than sedation, according to Luke Barr, MD, board-certified neurologist and chief medical officer of SensIQ.

“In short, it improves mental clarity and reduces anxiety without making you drowsy,” Barr told Verywell. “It can indirectly improve concentration by reducing mental noise and tension.”

This effect can be particularly beneficial under pressure.

“L-theanine supports focus by increasing brain wave activity associated with relaxed alertness,” said Oscar Coetzee, MS, DCN, senior director of clinical education at Designs for Health.

“It also influences dopamine and serotonin, promoting a balanced mood and reducing stress-induced distractions,” he added.

Together, these mechanisms can help clear mental fog and promote consistent focus, especially when you need to stay alert without feeling overstimulated.

How does coffee affect attention span?

Caffeine, the main active compound in coffee, helps you feel alert by blocking adenosine, a brain chemical that makes you sleepy. When caffeine kicks in, your brain ramps up its activity and releases more “feel good” chemicals like dopamine and norepinephrine.

It’s what gives you the familiar caffeine buzz: sharper focus, faster thinking, and an overall energy boost.

Caffeine also stimulates the adrenal system, triggering a process called gluconeogenesis, which is the release of stored energy into the bloodstream. According to Coetzee, this fuels the brain with more glucose, which increases levels of key neurotransmitters like dopamine and norepinephrine.

“The result is improved alertness, reaction time and mental energy,” he said.

Yet the benefits of caffeine can come with tradeoffs. “The effects of caffeine can also increase heart rate and nervousness, especially in those who are sensitive to it or who consume it on an empty stomach,” Barr said.

What happens when you mix them?

The combination of L-theanine and caffeine appears to create a synergistic effect, with each enhancing the benefits of the other while minimizing the harms.

The evidence backs it up: Research shows that pairing 200 milligrams (mg) of L-theanine with 160 mg of caffeine, about the amount in a cup of strong coffee, improves attention-shift accuracy, reaction time, and sustained focus compared to caffeine alone.

“L-theanine may blunt the hyperstimulating effects of caffeine by promoting relaxation without sedation,” Coetzee said. “This powerful combination often leads to what’s called calm focus, where you get clarity and alertness from the caffeine, without the jitters.”

He added that it makes it easier to concentrate, switch between tasks and maintain attention.

Are there any risks to take into account?

The combination of L-theanine and caffeine is safe and well tolerated by most healthy adults.

“There are no known adverse interactions,” says Coetzee. “However, individual responses may vary. Those who are very sensitive to caffeine or L-theanine may experience mild gastrointestinal discomfort, headaches, or changes in blood pressure.”

According to Barr, people with low blood pressure should be careful because L-theanine can lower it further. “People taking medications that affect serotonin, dopamine, or blood pressure should consult their doctor before taking supplements,” he said.

If you’re new to the combination, Coetzee recommends starting small: “Try a low dose (100 mg of L-theanine to match 100 mg of caffeine) to gauge personal tolerance.” »