L-Theanine for Women: Benefits, Side Effects and What Studies Measured

L-theanine is a calming amino acid from tea leaves, and for women it is mainly used for a calm mood, better sleep quality and steady focus without drowsiness. In a 4-week trial in which 21 of the 30 adults were women, with an average age of 48, 200 mg a day lowered scores on stress-related questionnaires and improved sleep quality and verbal fluency. Most people tolerate it well; in that trial cortisol did not change, and none of the trials described here measured estrogen.

Key Takeaways

• In a 4-week double-blind trial of 30 adults (21 women, average age 48), 200 mg of L-theanine a day lowered stress-related questionnaire scores and improved sleep quality, verbal fluency and executive function (Hidese et al., 2019).
• In adults aged 50 to 69 (27 of the 50 analyzed were women), a single 100.6 mg dose of L-theanine improved attention and working memory scores (Baba et al., 2021).
• A systematic review of 9 studies concluded that 200 to 400 mg a day may help people manage stress in stressful conditions (Williams et al., 2020).
• Paired with a little caffeine, L-theanine improved task switching accuracy and alertness in young adults (Giesbrecht et al., 2010).
• In the 4-week trial, cortisol levels did not change and no side effects were apparent.

What L-Theanine Does

L-theanine is an amino acid found naturally in tea leaves. It is not a sedative: the studies below tested it during the day for focus and attention as well as at night for sleep quality. That combination, calm without drowsiness, is why many women use it on busy days and before bed alike.

Research on L-theanine centers on how people handle everyday stress. A 2020 systematic review found 9 controlled studies and concluded that 200 to 400 mg a day may help reduce stress in people exposed to stressful conditions, while calling for larger and longer studies (Williams et al., 2020). Our guide to L-theanine benefits covers the general research.

L-Theanine Benefits for Women: What the Studies Measured

Two double-blind, placebo-controlled trials had more women than men, so their results speak directly to women:

Study	Who took part	Amount and length	What changed
Hidese et al., 2019	30 healthy adults, 21 women, average age 48, range 20 to 69	200 mg a day before sleep for 4 weeks, compared with placebo	Lower stress-related questionnaire scores; better sleep quality; better verbal fluency and executive function
Baba et al., 2021	50 healthy adults aged 50 to 69, 27 women	100.6 mg after breakfast, tested after one dose and after 12 weeks	Faster reaction time on an attention test and better working memory scores after a single dose

Calm mood and stress

In the 4-week crossover trial, each person took 200 mg of L-theanine a day and a placebo in turn. After L-theanine, scores on questionnaires about stress-related symptoms went down, and so did scores on the Pittsburgh Sleep Quality Index, a standard sleep quality questionnaire, where lower is better (Hidese et al., 2019).

Sleep quality

Compared with placebo, the same trial found greater improvement in three parts of the sleep questionnaire: time to fall asleep, sleep disturbance and the need for sleep aids. It was a small trial, but it lines up with how many women use L-theanine in the evening. Our guide to L-theanine for sleep goes deeper.

Focus and memory

The 4-week trial also found better verbal fluency and executive function scores after L-theanine. In the trial of adults aged 50 to 69, the clearest changes came after a single dose: reaction time on an attention test improved, and working memory scores rose. After 12 weeks, the differences from placebo were not significant (Baba et al., 2021), which suggests L-theanine works best as a support for focus on the day you take it. For a herb studied over weeks for memory, our guide to bacopa vs L-theanine compares the two.

L-Theanine for Women Over 40 and 50

These two trials were not run in students: the average age in the 4-week trial was 48, and the attention trial recruited only adults aged 50 to 69. So the results above fit women in midlife and beyond, whose everyday goals often include a calmer mood under pressure, better sleep quality and sharper focus. Neither trial was a menopause study, and L-theanine is not a menopause product. If you are going through menopause and take medication, talk with your clinician before adding anything new. If you are also weighing ashwagandha, our guide to ashwagandha for women covers its benefits over 50, dose and side effects.

L-Theanine With Coffee or Tea

L-theanine and caffeine are a well studied pair. In a controlled trial of 44 young adults, 97 mg of L-theanine with 40 mg of caffeine improved accuracy when switching between tasks, raised self-rated alertness and lowered self-rated tiredness compared with placebo (Giesbrecht et al., 2010). If coffee leaves you wired, pairing it with L-theanine is a simple step. Our guide to L-theanine and caffeine covers ratios and timing.

Does L-Theanine Affect Estrogen or Other Hormones?

None of the trials described here set out to measure estrogen, so they do not show an effect on it either way. The 4-week trial did measure cortisol, the main stress hormone, and found no significant change, along with no change in body mass index (Hidese et al., 2019). In other words, the calmer scores in that trial came without a measurable shift in cortisol. If you take hormone-related medication, check with your clinician first.

L-Theanine Side Effects for Women

Most people tolerate L-theanine well. In the 4-week trial of 30 adults, no one dropped out and no side effects were apparent during the study (Hidese et al., 2019). In the caffeine trial above, self-rated tiredness went down rather than up. Talk with your clinician before starting it if you are pregnant or breastfeeding or take prescription medicine. Our L-theanine side effects guide covers the details, and L-theanine dosage covers amounts and timing.

Where Our Theanine Nasal Spray and Saffron Capsules Fit

Our Theanine Nasal Spray gives 36 mg of L-theanine in every 2-spray serving, with alkaline water as the only other ingredient. It is caffeine-free, made with third-party tested ingredients, and absorbed through the lining of the nose, so some of each dose skips digestion. Use it with your morning coffee for calm focus or in the evening as part of a wind-down routine; it is part of our Focus Stack and Sleep Stack. Our L-theanine ingredient page and stress and mood guide cover the basics.

Coming soon, our Saffron Mood and Calm Capsules pair saffron extract 28 mg with L-theanine 200 mg per serving in the planned formula, the same daily L-theanine amount used in the 4-week trial above. Join the pre-order list on its page; no payment is taken. Our guide to saffron supplement benefits has a section for women.

Frequently Asked Questions

What does L-theanine do for women?

It supports a calm mood, sleep quality and focus without drowsiness. In a 4-week trial in which most participants were women, 200 mg a day lowered stress-related questionnaire scores and improved sleep quality.

What are the benefits of L-theanine for women?

Studies that included many women measured calmer stress scores, better sleep quality, better verbal fluency and, in adults aged 50 to 69, sharper attention after a single dose.

Does L-theanine affect estrogen?

The trials described here did not measure estrogen, so they do not show an effect either way. The 4-week trial measured cortisol and found no significant change.

Is L-theanine good for menopause?

L-theanine has been studied for everyday calm, sleep quality and focus in adults, including women in their 40s, 50s and 60s, not as a menopause product. If you are going through menopause and take medication, talk with your clinician first.

What are the side effects of L-theanine for women?

Most people tolerate it well; in the 4-week trial, no side effects were apparent. Check with your clinician first if you are pregnant, breastfeeding or take prescription medicine.

How much L-theanine should a woman take?

The trials used 100.6 mg and 200 mg a day, and a review of 9 studies pointed to 200 to 400 mg a day for stress. There is no separate dose for women.

Can women take L-theanine every day?

Daily use is how it was studied, for 4 weeks and 12 weeks in the trials above.

Should I take L-theanine in the morning or at night?

Either. The attention trial gave it after breakfast, and the 4-week trial gave it before sleep. Many women take it with morning coffee, in the evening, or both.

Sources

• Hidese S, et al. Effects of L-theanine administration on stress-related symptoms and cognitive functions in healthy adults: a randomized controlled trial. Nutrients, 2019. https://pubmed.ncbi.nlm.nih.gov/31623400/
• Baba Y, et al. Effects of l-theanine on cognitive function in middle-aged and older subjects: a randomized placebo-controlled study. Journal of Medicinal Food, 2021. https://pubmed.ncbi.nlm.nih.gov/33751906/
• Williams JL, et al. The effects of green tea amino acid L-theanine consumption on the ability to manage stress and anxiety levels: a systematic review. Plant Foods for Human Nutrition, 2020. https://pubmed.ncbi.nlm.nih.gov/31758301/
• Giesbrecht T, et al. The combination of L-theanine and caffeine improves cognitive performance and increases subjective alertness. Nutritional Neuroscience, 2010. https://pubmed.ncbi.nlm.nih.gov/21040626/

These statements have not been evaluated by the Food and Drug Administration. This content is for education and is not medical advice. Our products are not intended to diagnose, treat, cure or prevent any disease. Talk with a healthcare provider before starting a new supplement if you are pregnant, breastfeeding or taking medication.