What is L-Theanine?
L-Theanine is a unique amino acid found naturally in the tea plant (Camellia sinensis) and is known for its health benefits and role in giving the tea its distinct taste [1]. It’s the primary amino acid in green tea, making up about half of the total amino acid content [2]. You can also find L-Theanine in certain types of mushrooms [3].
What are the uses of L-Theanine?
L-Theanine is linked to a wide range of health benefits, particularly for its calming and stress-relieving properties, which have been extensively studied [4]. It’s known to promote relaxation, boost concentration, enhance learning, and even support weight loss [1]. Additionally, it may have neuroprotective effects, helping to improve cognitive functions like attention, memory, and learning [5].
L-Theanine is also believed to support the immune system. Research shows it can help counteract immunosuppression caused by intense physical activity and may reduce the risk of colds and the flu by boosting immunity [6]. Moreover, it has potential therapeutic benefits for certain cancers and cardiovascular diseases [1].
L-Theanine is also commonly used as a natural sleep aid and relaxant thanks to its ability to promote calmness without causing drowsiness [7]. Additionally, it shows promise in managing various health conditions, including obesity, arthritis, depression, and type 2 diabetes, highlighting its potential as a versatile therapeutic compound [8].
What is Cortisol?
Cortisol, a steroid hormone produced by the adrenal glands, is essential for several key bodily functions, including:
- managing stress,
- regulating the immune system,
- supporting nervous system activity,
- and controlling energy metabolism [9, 10, 11].
When the body senses a threat, the brain releases adrenocorticotropic hormone (ACTH), prompting the adrenal glands to release cortisol and adrenaline. This process is part of the body’s natural fight, flight, or freeze response, which prepares you to react to danger [11].
Cortisol plays a vital role in keeping your body functioning properly. It increases blood glucose levels, enhances the brain's ability to use glucose efficiently, and boosts the availability of substances needed for tissue repair. In stressful situations, it suppresses nonessential functions like digestion, reproduction, and growth while also modifying the immune system response to help the body focus on survival [12].
Maintaining healthy cortisol levels is critical for overall well-being. Chronic stress can lead to elevated cortisol levels, increasing the risk of health problems such as fatigue, anxiety, inflammation, and high blood pressure [13]. On the contrary, insufficient cortisol levels can result in conditions like Addison's disease or complications associated with Cushing's syndrome [9].
Keeping track of cortisol levels can offer important clues about a person’s overall health. Changes in cortisol secretion are often linked to psychiatric conditions, and stabilising these levels is frequently associated with improvements in the patient’s well-being [14]. Additionally, cortisol levels aren’t static—they can vary based on factors like the time of day, the season, and even where you live geographically [15].
Does L-theanine lower cortisol?
L-theanine has been associated with several health benefits, including stress relief and improved mental health [13]. Research suggests that L-theanine may impact cortisol levels, a hormone that the body produces in response to stress.
In a study involving patients with schizophrenia and schizoaffective disorder, L-theanine supplementation was associated with significant changes in cortisol levels. Another study on rats showed that high-dose L-theanine administration resulted in a decrease in corticosterone level, a hormone that is comparable to cortisol in humans.
While current studies hint at a potential connection between L-theanine and reduced cortisol levels, further research is necessary to better comprehend this relationship and its significance for human health.
Other ways to lower cortisol?
Lowering cortisol levels naturally can be achieved through several lifestyle changes, with stress reduction being one of the most effective approaches. Activities like practising yoga, ensuring adequate sleep, and reducing caffeine intake can significantly help manage stress. Spending time outdoors, taking relaxing walks, and prioritising self-care routines can also contribute to a calmer state of mind and lower cortisol levels [18].
Making changes to your diet by eliminating cortisol-triggering foods can be another helpful step in managing cortisol levels. In addition, regular moderate-intensity exercise, practising mindfulness and meditation, and spending quality time with pets can also reduce stress and support balanced cortisol levels. Supplementing with fish oil and ashwagandha has also been shown to be beneficial in lowering cortisol levels [19].
Taking a short nap, even just 10 minutes, can also be a great way to lower cortisol and manage stress. Other simple strategies include forcing a laugh or smile, maintaining good posture, muting phone notifications to avoid stress triggers, giving someone a hug, and listening to a happy song. These small actions can positively reduce cortisol levels and improve overall well-being [20].
In some cases, medications may be needed to manage cortisol levels. These could include treatments like somatostatin analogues, dopamine agonists, corticotropin-releasing hormone antagonists, and cortisol synthesis inhibitors. While these options show promise, more research is required to better understand their effectiveness and safety in the long term [21].