Can L-Theanine Supplements Actually Help You Relax and Focus?

3 min readA SUPPLEMENT THAT helps you relax and focus sounds like a no-brainer. Some supplement companies are suggesting that L-theanine is your answer. True, dietitians don’t exactly hate this supplement. There are some reasons to suggest L-theanine could do all the above to a certain degree. But there’s a significantly cheaper alternative everyone keeps overlooking. More on that below.What Is L-Theanine? L-THEANINE IS A compound found in tea that allegedly helps you relax and focus.“Have a demanding task at work late in the day but don't want coffee jitters? Tea's combination of caffeine and L-theanine can give you a calm yet alert mental state that could help boost productivity and effectiveness,” says Kate Ingram, MPH, RD, citing a popular study on caffeine and L-theanine published in Cureus. In supplement form, L-theanine typically has about 200 mg per serving. For context, that’s quite a bit more than the standard 6 milligrams or so in a cup of tea.What Are the Alleged Benefits of L-Theanine? L-THEANINE HAS A rare ability to pass through the blood-brain barrier. This semipermeable barricade protects your brain from toxins and other dangerous substances. Not all medications and supplements can safely pass through and affect the brain.Peak cognitive performanceSince L-theanine can pass through to the brain, companies have marketed the compound as a supplement for peak cognitive performance. There’s some science to suggest brain benefits.In clinical trials, 100 to 400 milligrams of L-theanine produced a “small but statistically significant” improvement in tasks involving visual attention. When paired with caffeine, people also showed greater cognitive performance than without. The cognitive benefits of L-theanine may even show up after a single dose. People who took one 200-milligram dose 30 to 60 minutes before a cognitive test showed higher scores in attention.Increase in calmnessLike a good cup of tea, an L-theanine supplement may reduce anxiety and stress. One review suggested 200 to 400 milligrams of L-theanine could calm people who regularly encounter stressful situations.Researchers decades ago also suggested that people who supplement with L-theanine may sleep more soundly and potentially stave off mental decline. “But the key word is suggest,” says dietitian Perri Halperin, RD. In recent years, scientists reviewing claims of L-theanine increasing alpha waves in the brain to improve sleep quality have found that “findings are often inconsistent.”Immunity boosterOne review suggested that L-theanine supplementation could help immune system function—in livestock. There are also studies finding evidence that L-theanine helped to reduce the risk of cancer. Again, in animals only. No supplement has yet been proven to boost immunity in people.What Are the Risks of Taking L-Theanine? “L-THEANINE IS GENERALLY recognized as safe; however, it is always best to consult your healthcare provider before starting any supplement,” says Ingram. This is especially the case if you have underlying health conditions or are taking other medications. L-theanine supplements could interact with some anti-anxiety, blood-pressure, and sleep meds. Side effects include headaches, dizziness, nausea, and jitteriness.Do I Really Need to Take L-Theanine? AS INGRAM PUTS it, “why start a supplement when you can just have a cup of tea?” Plus, with tea you have so many other health benefits such as its potential to improve gut health, promote weight loss, and protect you against chronic disease, Ingram says.Bottom line: You might get a more set dose of L-theanine if you take it in supplement form, but you'll be paying a lot for something you can get from just brewing a cup of tea. "Tea is certainly a cost-effective way to give it a try,” Ingram says. And, as always, talk to your doctor or a registered dietitian before beginning any type of supplement to ensure that it's something that will work best for you.Perri is a New York City-born and -based writer; she holds a bachelor’s in psychology from Columbia University and is also a culinary school graduate of the plant-based Natural Gourmet Institute, which is now the Natural Gourmet Center at the Institute of Culinary Education. Her work has appeared in the New York Post, Men's Journal, Rolling Stone, Oprah Daily, Insider.com, Architectural Digest, Southern Living, and more. She's probably seen Dave Matthews Band in your hometown, and she'll never turn down a bloody mary. Learn more at VeganWhenSober.com.