What Parents Should Know About L-Theanine

Step away from the supplement aisle — there are better ways to help your kid feel calm.

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If you’re a parent that has been to a grocery store recently, you’ve probably noticed a proliferation of supplements marketed toward your children. Or, rather, marketed directly at parents who would like their children to be calmer, more focused, more attentive and, well, just easier all around. Many of these products have tempting names like “Chillax,” “Kids Feel Calm,” “Kids, Cool, Calm & Collected” or even “Relax-a-Saurus.” These supplements have a variety of ingredients, from magnesium, lemon balm, and chamomile extract to GABA and passionflower, but they are unified by the fact that they all feature something called L-theanine.

But what is L-theanine, exactly, and is it actually safe for kids?

Many of these brands claim that their particular supplement has the power to reduce stress and increase focus and attention — claims that are appear to refer (if not explicitly) to attention-deficit hyperactivity disorder (ADHD) and other attention, focus, or behavioral challenges parents may be facing. If you spend time on social media, many TikTok and Instagram influencers also promote the use of products containing L-theanine — on those platforms, they’re sometimes referred to as “bedtime vitamins,” which further contributes to the message that these products are safe.

However, parents should be very cautious, says Dr. Cora Breuner, a pediatrician at Seattle Children’s Hospital and a specialist in adolescent medicine. Whether they are effective, safe, and what an appropriate kids’ dosage of L-theanine might be is currently unknown. “People assume because it is natural, it’s perfectly safe. And it isn’t,” Breuner says.

What is L-theanine?

L-theanine is an amino acid that occurs naturally in green tea and some mushrooms. Breuner cautions that information right now on safety and efficacy of L-theanine as a treatment for ADHD or anxiety is lacking. “Does it work? And at what dose? There’s not a lot of data,” she says. One pediatric study looked the possibility that L-theanine supplements may improve sleep quality in kids with ADHD, but the study was small and concluded that larger studies were needed. Another looked at whether a specific combination of L-theanine and caffeine improved focus in children with ADHD, and found possible efficacy, but again, as Breuner stresses, it’s too early to say exactly what dose is safe, and whether any potential benefits out weigh risks. She’s particularly wary of the fact that L-theanine is often paired with caffeine, which is known to inhibit growth in children.

Is it OK for kids to take L-theanine?

It may ultimately be found to be safe, but right now, there’s nothing proving that it is. L-theanine hasn’t been studied much yet, and has barely been studied in children — certainly not enough for pediatricians to be able to confidently recommend a particular dosage, Breuner says. Also concerning, she says, is the fact that the FDA does not regulate the supplement industry in the same way they regulate the pharmaceutical industry. Rather, supplements are considered a subcategory of food. This means that they are not closely vetted, and studies have found that supplements often do not contain exactly what they claim to contain.

So, even if pediatricians knew of a safe L-theanine dosage for kids — which they currently do not — parents could not necessarily trust that the L-theanine product that they see on the grocery store shelf or buy online contains the dosage it claims to. It may have much less, or — more concerningly — much more L-theanine than it claims to. In fact, a research letter published in the The Journal of the American Medical Association in April of this year looked at a slew of currently available melatonin supplements and compared the dosage-per-gummy claim with what was actually in each gummy. “What they found is that, in some of them, there is 150% more than there is supposed to be,” Breuner says. “Let the buyer beware. You have no idea what you’re putting into your child.”

Is there a safe L-theanine dose for a child with ADHD?

If you suspect your child has ADHD or if they are struggling with behavioral issues at school, Breuner urges you to reach out to your child’s health care provider rather than reaching for a supplement containing L-theanine, or any supplement at all for that matter. There simply isn’t enough evidence yet about the safety or efficacy of L-theanine for pediatricians to recommend a particular dosage that’s absolutely safe. In her own practice, Breuner encourages families to seek out evidence-based support for behavioral challenges. She often offers ways for families to learn tools from cognitive behavioral therapy (CBT), because there is enough evidence to show efficacy, and because these kinds of behavioral tools are safe.

“When someone comes to me asking for help to calm their kid down, I want to respond with, ‘What else have you tried?’ There are studies on warm milk. There are studies on chamomile. On exercise, on sleep. There are so many studies out there — research-based placebo-control studies for those kinds of behaviors — versus just turning towards the supplement,” Breuner says.

The bottom line: What parents need to know about “calm” ADHD supplements for kids

Parents should be extremely cautious when it comes to purchasing supplements for children — and for themselves, for that matter. Because the FDA regulates supplements as food instead of as medication, manufacturers can introduce anything into the market that they believe is safe, without the product needing to undergo the kind of rigorous vetting that a medication would be subject to. Even the FDA’s own statement on supplements urges caution, saying, “Many dietary supplements contain ingredients that have strong biological effects which may conflict with a medicine you are taking or a medical condition you may have.”

Breuner urges parents to be wary and always talk with their pediatrician or health care provider before purchasing an L-theanine supplement, or any supplement, for your child. “I’m not saying everything’s evil about this, or parents are doing wrong by their kids. But I’m just saying be aware that what you’re buying may not have what it says it has in it, nor may it ever have been studied in someone your child’s age or size,” Breuner says.

Studies cited:

Cohen, P.,(2023) Quantity of Melatonin and CBD in Melatonin Gummies Sold in the US. The Journal of the American Medical Association.

Lyon, M., Kapoor, M., (2011) The effects of L-theanine (Suntheanine®) on objective sleep quality in boys with attention deficit hyperactivity disorder (ADHD): a randomized, double-blind, placebo-controlled clinical trial. Alternative Medicine Review.

Kahathuduwa C., Wakefield S., West, B., Blume, J., Mastergeorge, A., (2019) L-theanine and Caffeine Improve Sustained Attention, Impulsivity and Cognition in Children with Attention Deficit Hyperactivity Disorders by Decreasing Mind Wandering. Current Developments in Nutrition.


Dr. Cora Collette C Breuner, M.D., MPH, a member of the Division of Adolescent Medicine and the Orthopedics and Sports Medicine Department at Seattle Children’s Hospital, and a professor of pediatrics and adjunct professor of orthopedics and sports medicine at the University of Washington School of Medicine

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