Tea Lessens Anxiety Through Action Of L-Theanine

Many types of tea (from the Camellia sinensis plant), including green, white, black, and oolong contain L-Theonine.

I’ve been drinking more tea to get more fluid. I noticed that after drinking tea I felt calmer. For a while I assumed it was the whole experience of taking a break, sipping a warm beverage, etc. But it seemed more than that so I did a bit of research.

Tea contains L-theanine, an amino acid that has been shown to have an anti-anxiety effect. It increases dopamine and serotonin levels in the brain and increases production of alpha waves, which are more predominant in a resting state.

Psychotropic Effects Of L-Theanine And Its Clinical Properties: From The Management Of Anxiety And Stress To A Potential Use In Schizophrenia, Pharmacological Research, September 2019

Anxiety disorders are highly prevalent in modern societies, and are ranked the sixth most important contributor of non-fatal negative health outcomes. L-theanine is an amino acid naturally found in green tea (Camellia sinensis) and some other plant extracts, and recent clinical studies have proposed promising adjuvant effects of L-theanine for the negative impact of anxiety and psychological stress* on health.

* Psychological stress can be defined as acute, for example in anticipation to a surgical procedure, or chronic, for example in financial or family difficulties. Both forms of stress have the potential to disrupt the nervous, endocrine and immune systems.

Anxiety and stress outcomes

Overall, several studies have shown that the administration of L-theanine improved anxiety and stress outcomes, alongside improvements in other manifestations such as depression and psychopathological symptoms.

Additionally, verbal memory and executive function were improved.

Most of the studies appraised in our review recruited from 12 to 60 participants, were double-blinded and tested the effects of L-theanine in doses ranging from 15 to 400 mg.

Blood pressure lowering effects

L-theanine may have the potential to lower blood pressure, possibly indirectly via reduction of the manifestations associated with stress, inhibiting cortical neural excitation and consequently attenuating sympathetic activity.

Major depressive disorder (MDD)

Hidese and colleagues found that L-theanine administration reduced depressive symptoms and improved cognitive function in MDD patients.

Natural sleep aid

Overall, it is suggested that the intake of 200 mg of L-theanine at bedtime may improve sleep quality by anxiolysis [decreasing anxiety] rather than sedation.


Structurally, L-theanine is a glutamate analogue, hence binding to the same glutamate receptors and therefore hindering the neuroexcitatory effects triggered by glutamatergic activation. It is believed that L-theanine mediation on glutamatergic neurotransmission is the main pathway by which this non-proteinaceous amino acid is able to attenuate anxiety disorders and mitigate the negative outcomes of exposure to acute and chronic stress.

Furthermore, similarly to GABA administration, L-theanine was able to significantly increase the generation of alpha waves, which are more predominant in adults at rest with eyes closed, but also in relaxed conditions. … Studies employing animal models have found that the administration of L-theanine seems to increase GABA* levels in the brain.

[Studies in animals] given L-theonine have found higher levels of dopamine and serotonin.

*GABA: Gamma-aminobutyric acid, the chief inhibitory neurotransmitter in the brain.

Some other good reading on the topic:
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, November 2019

The paper below found that black tea had more L-Theanine than green but other studies found the opposite. It’s about ten years old so the tea we’re buying today is a different animal than the tea they tested. It did find, however, that adding milk lowered the L-Theanine content. (Most of the L-Theanine is extracted within the first 5 minutes of brewing.)
How Much Theanine In A Cup Of Tea? Effects Of Tea Type And Method Of Preparation, Food Chemistry, 2011

From the Introduction:

L-Theanine is a non-proteinogenic amino acid found in tea (its primary dietary source) and a derivative of the amino acid glutamic acid. Tea is the most widely consumed beverage worldwide after water and is generally seen as a relaxing drink, whereas coffee is seen as more of an energising drink. Although both drinks contain caffeine, L-theanine is only present in tea. This difference has led to an interest in the effects of L-theanine on psychological measures, such as stress and anxiety. L-Theanine has been found to have a relaxing effect and to increase alpha brain waves, synonymous with a relaxed yet alert state. Recent research has found that L-theanine reduced both subjective and physiological stress responses during a stressful task situation and that it may be useful for reducing raised blood pressure. This relaxation effect of L-theanine may also explain the improvements seen in subjective sleep quality and mood upon awakening after L-theanine.

So, the relaxing effect may have been from the tea itself, in addition to the tea-drinking experience.

Our Ability To Focus May Falter After Eating One Meal High In Saturated Fat

This is a McDonald’s Sausage Biscuit with Egg. The meals supplied in the study were “designed to mimic the contents of various fast-food meals” such as this sandwich.

Our Ability To Focus May Falter After Eating One Meal High In Saturated Fat, Science Daily, 12 May 2020

The study compared how 51 women performed on a test of their attention after they ate either a meal high in saturated fat or the same meal made with sunflower oil, which is high in unsaturated fat.

Their performance on the test was worse after eating the high-saturated-fat meal than after they ate the meal containing a healthier fat.

The loss of focus after a single meal was eye-opening for the researchers. … Most prior work looking at the causative effect of the diet has looked over a period of time.

“If the women had high levels of endotoxemia*, it also wiped out the between-meal differences. They were performing poorly no matter what type of fat they ate,” Madison said.

Possible mechanism:

Previous research has suggested that food high in saturated fat can drive up inflammation throughout the body, and possibly the brain. Fatty acids also can cross the blood-brain barrier.

* I talked about endotoxemia in this post:

One way dietary fat contributes to inflammation is by increasing absorption of endotoxins, to which we launch an inflammatory response. Endotoxins are bits of bacterial membrane that are absorbed along with the fat we eat, especially saturated fat to which endotoxins have an affinity. They’re thought to derive from bacteria (dead or alive) introduced to the intestines from food, primarily meat, eggs, dairy, or fermented food, all of which carry relatively higher levels of microorganisms. The bacteria that colonize our colon are too far along the digestive tract for absorption to take place in any significant quantity.

Here’s the study:

Afternoon Distraction: A High-Saturated-Fat Meal And Endotoxemia Impact Postmeal Attention In A Randomized Crossover Trial, American Journal of Clinical Nutrition, 12 May 2020

It was a good study: double-blind, randomized crossover trial of 51 women. It concluded:

These results suggest that higher LBP, sCD14, and LBP:sCD14 [these are endotoxemia markers] and saturated-fat intake individually and jointly influence attention. Endotoxemia may override the relative cognitive benefit of healthier oil choices.

Both meals were high in fat and both contained animal food (eggs, turkey sausage) which provide the bacterial bits for endotoxemia. Remove the animal food and reduce the fat and you might have seen even better results.

“Because both meals were high-fat and potentially problematic, the high-saturated-fat meal’s cognitive effect could be even greater if it were compared to a lower-fat meal,” [lead author Madison] said.

Study: “A Single Day of Excessive Dietary Fat Intake Reduces Whole-Body Insulin Sensitivity”

Each small assault to the tiny blood vessels in our eyes and kidneys and brain that occur when we indulge reduces the function of those organs. In young healthy people, damage is repaired quickly. Not so in older people. We would have patients in our practice show up after Christmas with blurry vision and worse kidney function. And when we asked them what they ate… *

When your body becomes less sensitive to insulin, your blood glucose goes up. Regular binging leads to regular bouts of high blood glucose. High blood glucose damages small blood vessels in the eye and kidney over time (diabetic retinopathy and nephropathy are the largest contributors to blindness and end-stage renal disease in this country). High blood glucose also causes high blood pressure by reducing nitric oxide.

A Single Day of Excessive Dietary Fat Intake Reduces Whole-Body Insulin Sensitivity: The Metabolic Consequence of Binge Eating, Nutrients, 17 August 2017

We know eating big, fatty meals regularly is deleterious:

Consuming excessive amounts of energy as dietary fat for several days or weeks can impair glycemic control and reduce insulin sensitivity in healthy adults.

But what if you only indulge for one day?

One day of high-fat overfeeding increased postprandial glucose area under the curve (AUC) by 17.1% (p < 0.0001) and insulin AUC by 16.4% (p = 0.007). Whole-body insulin sensitivity decreased by 28% (p = 0.001).

In conclusion, a single day of high-fat, overfeeding impaired whole-body insulin sensitivity in young, healthy adults. This highlights the rapidity with which excessive consumption of calories through high-fat food can impair glucose metabolism, and suggests that acute binge eating may have immediate metabolic health consequences for the individual.

Also deleterious.

This study tested high calorie, high fat. What if instead it was high calorie, high carbohydrate?

Whether feeding excess energy in the form of carbohydrates (particularly added sugars, which are also highly palatable) for a single day has the same effect remains unclear. However, overfeeding a carbohydrate-rich diet (40% increase in energy intake; 60% of energy from carbohydrate) for five days was found to elicit changes in skeletal muscle cellular signaling that are typically associated with increased insulin sensitivity. … These data suggest that excessive consumption of dietary fat reduces whole-body insulin sensitivity, rather than a positive energy balance alone.

Eating high calorie, high carbohydrate had a positive effect, it increased insulin sensitivity!

The cohort studied were young, healthy, non-obese males and females who were recreationally active. Older people with chronic diseases would probably have worse outcomes.

It is plausible that the dietary intervention used in the current study may produce a more dramatic effect in populations at risk of developing T2DM (e.g., sedentary, overweight individuals).

Repeated periods of binge eating leads to a progressive worsening of glycemic control. Based on our data, it is plausible to suggest that the metabolic effects of binge eating may have more marked effects in individuals at risk of insulin resistance or the metabolic syndrome.

* The photo up top is a screen cap from the video below. It’s regular fare at the Greenwich Market in London. The sandwich is called “Seriously Cheesy Toastie loaded with Smoked Pulled Pork.”

Another Fanatic Cook

If I was ever going to post a selfie, it would look like this:

I saved this from a National Geographic article on Okinawa several years ago. Everything in this photo, I feel, is me. Except for the coat. Too much fabric while cooking. And the watch. Maybe he dressed up for the photograph.

I love how he attends the pot. That’s my life. Attending pots.

Bee Drinking

Did you know that it takes a worker bee her entire life to make just one teaspoon of honey for her queen? When we take away bees’ honey, we reduce their ability to survive. We take away their reason for being. And we use them as some kind of manufacturing plant.

We humans have a lot of evolving to do to become compassionate creatures. I sure do.

Here’s a bee that let me take its photo while it was drinking. The difference between these two photos is the tongue. My God, days aren’t long enough for me to discover all this.

Bobby Darin

I just finished watching this Bobby Darin expose on PBS:

It’s odd where I find my inspiration in life. I found some reading about him. He died at the age of 37 from what is thought to be heart complications of rheumatic fever he had when he was 8. He believed his life would be short so he did as much as he could with it. He didn’t just sing pop songs, he made albums, wrote songs, and played several instruments – all well. (You should see him play the drums!) He even acted, which was something else he did well: “In 1963, he was nominated for an Academy Award for Best Supporting Actor for his role as a shell-shocked soldier in Captain Newman, MD.”

He was talented, smart, likable, and quite resilient, especially after finding out that the woman he thought was his sister was actually his mother, that the woman he thought was his mother was actually his grandmother.

What drew me into all this was looking up this song, which I have always liked. Beyond The Sea:

I like this one too. Heartbreaking for me to watch it. He died just nine months later on 20 December 1973. He knew he was, as he said, “very sick” at the time. (He had heart valve replacement surgery in 1971.)