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L-Theanine MYSTERIOUS Effects On Libido

  1. Hey all,
    It has been some time since I've been meaning to make a post on L-Theanine and it's harsh effects on male sexual function.
    I amongst many (on reddit) have found an extreme paradoxical reaction to L-Theanine (same case with ashwagandha) on erectile function.

    Let me explain.

    I have re-run this experiment over 5 times now to see if it produces the same result, and it has been consistent.

    L-Theanine (Suntheanine) brand does this to me every single time.
    -Ultra strong reduction in anxiety and significant improvement in thought processes
    -I notice muscle spasms around my eye-lids, stomach and even perineum region.
    -Strange effect urinating/unfinished urination
    -NUMB P****
    -Ultra elated mood, but zero sexual drive/arousal.

    Now whoever can help me figure this out, I will be extremely grateful.

    I am suspecting the following possibilities:
    -L-Theanine suppresses DHT, but hasn't been discovered yet
    -L-Theanine blocks histamine so much that it results in zero arousal
    -L-Theanine blocks Glutamate so much that it results in zero arousal
    -L-Theanine causes 5ht1a receptor agonism?
    -L-Theanine drops prolactin too much?
    -L-Theanine might have some sort of undiscovered hormonal effect.
    -L-Theanine might be causing sphincter dysregulation?

  2. L-theanine --> GABA agonism --> Lowered cortisol --> Reduced hypersexual response
  3. I get complete ejaculatory anhedonia on l-theanine
  4. I am so confident that is what it is happening to me too. I am thankful I'm not the only one. Have you found a potential mechanism of action behind this? Ie. How can we counteract this effect?
  5. Usually people on this forum report that lowering cortisol is generally useful for improving libido...?
  6. It's definitely Serotonin/histamine/Adrenaline lowering. Those three are so closely connected.
  7. Thanks for the input. I also suspected these 3 play an intimate role. Perhaps the histamine lowering effect is the cause? I have pure Histidine on standby here... maybe I should dose L-Theanine and then 3 hours later try using L-Hisitidine...?
  8. How much are you taking?
  9. I used it anywhere from 100mg-300mg. I am too scared to even touch it again now... But if it's for science, then I'll do it for everyone. I just desperately want to understand the exact mechanism behind it... so that I can offset it. Because Theanine is a star performer for my level of mental capacity/social confidence.
  10. @Lokzo nope. I just moved on, forgot about it. People forget that isolated aminos can be problematic and peat never has recommended them. Sure he’s written about Theanine but that doesn’t mean he recommends it.
  11. Theanine - Scientific Review on Usage, Dosage, Side Effects

    4.1. Kinetics and Mechanisms

    Theanine has been found to cross the blood brain barier, as systemic injections[20] and oral intake[21] can increase brain concentrations of the compound which appears to be mediated via the leucine-preferring transport system[22] (the neutral amino acid transport[23]).

    Following oral intake L-theanine reaches the brain within an hour and is elevated up to 5 hours, which it then proceeds to get eliminated ultimately having no concentrations left at 24 hours post oral intake (4,000mg/kg).[21] The concentrations reaching the brain at this oral dose are around 2µM/g[21] and serum concentrations in this study peaked at above 12.5µM/mL within an hour, and were reduced to similar concentrations as the brain at 16 hours.[21]

    Specific brain organs that have been shown to have increases in theanine concentration following oral intake include the hippocampus.[24]

    4.2. Catecholamines
    Dopamine and noradrenaline do not appear to be significantly influenced with oral intake of theanine in rats (2% of drinking water, sufficient to increas plasma theanine to 7763.3+/-3875.4nmol/g) over 3 weeks.[1]

    Direct injections of theanine into the striarum also cause dose-dependent increases in dopamine secretion for 40 minutes before returning to baseline.[22]

    10µM/kg injections of theanine have been noted to reduce noradrenaline by 16% and 9% at 30 and 75 minutes, respectively; this was abolished with coadministration of caffeine.[33]

    4.3. Serotonin
    Oral intake of theanine which increases plasma theanine to 7763.3+/-3875.4nmol/g (2% of rat drinking water) has failed to significantly influence serotonin concentrations.[1]

    10µM/kg injections have failed to significantly influence serotonin levels per se, but have been able to attenuate a caffeine-induced increase in serotonin.[33]

    L-Theanine at an oral dose of 2,000-8,000mg/kg in rats (human estimated dose of 320-1280mg/kg) cause a dose dependent increase in brain tryptophan and reduction of serotonin, reaching 20.5% and 15.5% at the highest dose.[34]

    Technically has anti-serotonergic mechanisms, but this occurs at a very high dose and likely isn't relevant for standard oral supplementation

    4.4. GABAergic mechanisms
    Injections of theanine (30µM/kg only; 15µM/kg being ineffective and all doses higher than 30µM/kg being ineffective) have been found to increase cerebral concentrations of GABA by 19.8% following.[20]

    Conversely, 4% L-theanine in the drinking water of rats has been noted to reduce extracellular GABA in the frontal cortex.

    4.5. Glutaminergic mechanisms
    L-Theanine has been found to have affinity for all three glutamate receptor subsets with IC50 and Ki values (respectively) of 24.6+/-0.9µM/19.2+/-0.7µM (AMPA), 41.5+/-7.6µM/29.3+/-5.4µM (Kainate), and 347+/-47µM/329+/-44µM (NMDA); these were 80-30,000 fold less potent than the endogenous ligand L-glutamate.[35]

    Theanine has been found to accumulate in glutaminergic neurons (via two mechanisms with KM values of 42.3μM and 1.88mM) with at least one being the glutamine transporter, as the two amino acids compete for uptake (glutamine inhibits with an IC50 of 329.2+/-59.5μM while the opposite inhibition is weaker, at greater than 1,000μM).[36] It has been noted that incubation with 1-10mM theanine was able to also suppress extracellular glutamate concentrations.[36]
  12. It certainly does something. It's difficult to find a comparison.

    Maybe low dose LSD ? Maybe alcohol ? Maybe phenibut ? It is strange stuff.

    It also increases empathy and depression a bit too , which I don't like.
  13. Really interesting link paymanz

    I wonder if theanine would be useful with 'nofap'
  14. I quit taking isolated amino acids like taurine, theanine, and lysine except only one supplement which is glycine. Taurine gives me bad skin and chubby lips. Lysine makes me retain water in my body. Theanine is not as powerful as I thought. It just makes me meh and not at my best. Glycine is the only isolated amino acid I think that's worth supplementing especially if you eat steaks and muscle meats at restaurants.
  15. Yeah my empathy was enhanced like 3-fold on theanine. Today I tried L-Histidine to test whether Theanine's arousal reducing effect is due to low histamine, but sadly it has had no effect.
  16. I might start back on Glycine before bed. Thanks for the friendly reminder aha
  17. Since almost 2 days since L-Theanine, I can start to notice my libido is coming back. I am also having high doses of Panax Ginseng and Siberian Ginseng which seems to be assisting this process.
  18. When you say theanine makes you lose libido, is it because of the NUMB **** you get from it? When I was taking it long time ago, I don't remember specifically it affected my libido, maybe in the first week it increased my dopamine and made me horny but that didn't last long mind you.
  19. It just diminishes ALL sensations in the brain and P****. Even days after, I feel like the orgasm intensity is substantially reduced. Honestly can't figure out a way to normalise myself because we still don't know the mechanism of action.
  20. Endogenous opioids, endocannibinoids, serotonin, and prolactin are all involved in the sensation of orgasm (the 'reward') and the subsequent refractory period.

    Dopamine, melanocortins, norepinephrine, and oxytocin are more involved in arousal.

    Theanine definitely has some influence on dopamine, norepinephrine, and serotonin levels but the impact seems to depend on the context.

    Brain Res Bull. 1997;44(4):397-407.
    Implications of immediate-early gene induction in the brain following sexual stimulation of female and male rodents.
    Pfaus JG1, Heeb MM.
    Induction of immediate-early genes (IEGs), such as c-fos, has been widely used to mark the activation of brain regions following different types of sexual stimulation and behavior. A relatively common set of hormone-concentrating basal forebrain and midbrain structures in female and male rodents is activated by copulatory stimulation, in particular, stimulation of sensory nerves that innervate the penis or vagina/cervix, olfactory or pheromonal stimuli, and conditioned sexual incentives. These regions include the preoptic area, lateral septum, bed nucleus of the stria terminalis, paraventricular hypothalamus, ventromedial hypothalamus, medial amygdala, ventral premammillary nuclei, ventral tegmentum, central tegmental field, mesencephalic central gray, and peripeduncular nuclei. Regions that do not contain classic intracellular steroid receptors, such as the ventral and dorsal striatum or cortex, are also activated. IEGs have also been colocalized with cytoplasmic proteins like GnRH and oxytocin, and have been used in conjunction with retrograde tracers to reveal functional pathways associated with different sexual behaviors. Steroid hormones can also alter the ability of sexual stimulation to induce IEGs. Despite the many similarities, some differences in IEG induction between sexes have also been found. We review these findings and raise the question of what IEG induction in the brain actually means for sexual behavior, that is, whether it indicates the perception of sexual stimulation, commands for motor output, or the stimulation of a future behavioral or neuroendocrine event related to the consequences of sexual stimulation. To understand the role of a particular activated region, the behavioral or neuroendocrine effects of lesions, electrical stimulation, drug or hormone infusions, must also be known.

    Sci China Life Sci. 2012 Dec;55(12):1064-74. doi: 10.1007/s11427-012-4401-0. Epub 2012 Dec 12.
    L-theanine inhibits nicotine-induced dependence via regulation of the nicotine acetylcholine receptor-dopamine reward pathway.
    Di X1, Yan J, Zhao Y, Chang Y, Zhao B.
    In this study, the inhibitory effect of L-theanine, an amino acid derivative of tea, on the rewarding effects of nicotine and its underlying mechanisms of action were studied. We found that L-theanine inhibited the rewarding effects of nicotine in a conditioned place preference (CPP) model of the mouse and reduced the excitatory status induced by nicotine in SH-SY5Y cells to the same extent as the nicotine receptor inhibitor dihydro-beta-erythroidine (DHβE). Further studies using high performance liquid chromatography, western blotting and immunofluorescence staining analyses showed that L-theanine significantly inhibited nicotine-induced tyrosine hydroxylase (TH) expression and dopamine production in the midbrain of mice. L-theanine treatment also reduced the upregulation of the α(4), β(2) and α(7) nicotine acetylcholine receptor (nAChR) subunits induced by nicotine in mouse brain regions that related to the dopamine reward pathway, thus decreasing the number of cells that could react to nicotine. In addition, L-theanine treatment inhibited nicotine-induced c-Fos expression in the reward circuit related areas of the mouse brain. Knockdown of c-Fos by siRNA inhibited the excitatory status of cells but not the upregulation of TH induced by nicotine in SH-SY5Y cells. Overall, the present study showed that L-theanine reduced the nicotine-induced reward effects via inhibition of the nAChR-dopamine reward pathway. These results may offer new therapeutic strategies for treatment of tobacco addiction.
  21. I've been using 1 gram daily. I'll lower the dose to 500mg to see if there's any difference.
  22. I get harsh effects on libido from 1 cup of green tea. Very bizarre, took me years to realise. I'm now fully aware that even seemingly harmless substances can have dramatic effects lasting days.
  23. What does 1 gram daily feel like? Do you take it with any other supplements?
  24. Quite sad really. Green Tea has so many other benefits, but now sadly you can use it.
  25. Peat would probably say it's because green tea is highly estrogenic or loaded with fluoride, but I doubt that most people get significantly affected. I feel almost ashamed to say that a little cup of tea can change my libido for 24 hours.
  26. Well if it makes you feel bettter, high amounts of reheated boiled potatoes cause the same issue for me. I suspect the Butyrate production is affecting the 5HT1A receptors (Antidepressant-like effects of sodium butyrate in combination with estrogen in rat forced swimming test: involvement of 5-HT(1A) receptors. - PubMed - NCBI)
  27. I use b vitamins, fat solubles, androsterone, NDT, glycine, taurine, creatine and a dopamine agonist. I don't remember how I felt on theanine. If I had negative effects, I did not notice because I wasn't expecting any after reading all the benefits of theanine(aside from using other supplements). I lowered the dose to 500mg and this time I'll pay attention to how I feel.
    edit: low dose boron, manganese, lithium(traces/very low dose) and aspirin.
  28. Cool, thanks for sharing your neat stack. As far as B-Vitamins are concerned... is there a reason why you include it in your daily routine? I understand they are water soluble, but I have seen many people report neurotoxicity with high doses of b-Vitamins, particularly B6.
  29. To compensate for the empty calories that I get from table sugar, among other positive effects discussed here. I think Ray Peat has discussed B6 dosage; I personally take 10mg of B6 powder.
  30. I just started taking a B-Complex and all of a sudden my old-school libido has finally returned. I have no idea how/why, but I will try Theanine one more time to see if the B Vitamins can counteract the horrendous side effect.
  31. Are you sure it was the theanine? That's a strange reaction.What brand did you use and how much?

    How did it go? how much theanine were you taking?
  32. I dont know about studies behind theanine but I can say that its good substitute for cyproheptadine in higher doses and I am feeling much better on it than on cypro.
  33. For me it lowers the hypersexual response people talk about on here. That's related to adrenaline/serotonin/estrogen.

    No fap becomes simple, rather than aggrivatingly painful.

    I have been using L-Theanine and taurine to great length in both person/sexual life. Theanine/taurine in small doses through the day not only have greatly increased dopamine levels but also gaba. So I am both more productive and super chilled out. People have taken note since of cortisol free face/movements. Hard to explain. but makes u "alpha".

    Since alpha male monkeys are found to have the highest dopamine and lowest gluticords hormone levels. Humans being primates pick up on this stuff subconciouesly and it's greatly effects strangers perception of you. I study this stuff and test it in real life, it has been my experience so far. Women seem to really notice.

    Also adding theanine 200mg to a single drink is all I need for social lubercation before dates/Bar nights.
    Gaba levels increase greatly and ur personality flows out. Rather than taking shots into stupor.

    Some l theanine/taurine before class is the same thing.
  34. repost
  35. Thank you for your first post. I thought I was going mad before I read it. I had a stress attack 6 months ago & not wanting to take the nasty stuff the doctors prescribed I started taking L Thiamine 250mg every morning & indeed it changed my life, within a day I was out cycling mingling in crowds. It was brilliant, however over time I found I became total, i.e. 100% disinterested in sex in any way, shape or form and last week I was considering getting psychiatric help until the other night I put the 2 words "Monks & Green tea" together & thought why do Tibetan Monks drinks gallons of green tea. Yes we know it flattens Alpha waves & makes one thoughtful, but could the L Thiamine also have another "benefit" for monks in the crushing of any sexual distraction. Thats when I started searching & found your post. I have just read you are now taking Ginseng, PLEASE stop, this stuff can completely turn you into a lunatic, I took it when I was young & I am convinced it wrecked my first marriage. Just try taking NOTHING for a month & see what happens. Again thanks for your post, PS I get every single symptom that you get.
  36. A couple of months ago I went away for 4 days & decided to not take anything & only a bit of L Theanine. For some reason I (I presumed it was because I was away from home in a splendid hotel) I started sleeping really heavily. I'd get up for breakfast and then go back to bed and sleep till 1pm. This is very uncharacteristic of me.

    It is now only 24 hours since I cut my LTheanine dose from 500mg/ day to just 50mg yesterday morning & the same happened last night, I got up at 9AM & then went back to bed, it felt so damn comfortable & cozy, like being immersed in a bath of goose feathers ............I have now realised what what happening, L Thiamine numbs the nerve endings THROUGHOUT the whole body, not just the P****. This is why the bed felt so nice, my nerve endings had switched back on.

    I think there should be warnings for L Theanine, everyone pops them like sweets because they are "Natural" but I think it is a very powerful drug & dosage is critical. The drug is also able to shroud any erotic thoughts you may have in a mist, it is even able to block the action of Viagra (Which the doctor prescribed) & now by finally by numbing the body actually placing it in a state of anaesthesia, it ensures that any thoughts or plans of sexual fulfilment of any kind will vanish from your life.

    The calming effect of L Theanine is I believe is a SIDE EFFECT of its main purpose as an anaphrodisiac.

    Worse still you will only find out by accident because it is impossible to blame a "Natural" calming substance as the villain in perhaps the destruction of your marriage or relationship.Here is an interesting extract from Wiki on Anaphrodisiacs in which it claims no "Reliable" medication is known.......well there is one and its called L Thiamine, maybe that could be added to "Citation needed?" (Maybe it is acting on the same part of the brain as the opioids named below?)

    Opioids, the class of pain-reducing substances which include morphine, heroin, and hydrocodone, are anaphrodisiacs.

    Side effects of certain antidepressant medications may be anaphroditic in nature (e.g. SSRIs and certain antipsychotics); however, there are no prescription psychotropic drugs that have reliable anaphroditic effects.[citation needed].
  37. Can you "Enlarge" on your claim (No pun intended LOL) as there are so many natural products that claim to increase Libido its difficult to believe any of them?
  38. Too many side effects reported. L-Theanine is not safe.
  39. Just found this thread. It's been a couple years since I tried it but L-Theanine had a negative effect on my boners too. Green tea had a negative effect too. I didn't record dosages so I can't provide that here.
  40. Wow, another guy affected. We still don't understand the mechanism of action. I'm waiting for more research papers. Is it possible the 5-HT1a receptor was involved?!
  41. I think if it’s really adrenaline blocking it might be the cause. I thought a certain degree of adrenaline is needed for arousal as in arousal increases heart rate a little. Without this type of arousal you’re just chill and dont really get any response.

  42. Hmmm maybe this is the rebound that I crave when Cyproheptadine wears off?!
  43. what are your thoughts on this then? I was thinking of doing sports research 200mg of suntheanine just 3 days a week. I was also going to add in taurine, olive leaf extract and ashwaganda.
  44. wikipedia says theanine raises serotonin, dopamine, glycine and gaba. it seems to vary individually, and maybe by dosage/diet, whether it raises or lowers serotonin. i got some suntheanine but idk if its worth trying now.
  45. I’m blaming theanine for weak erections and weaker libido. For me, if I’m going to a social event, it’s great but doesn’t help for closing “deals”..

    I think this one is staying on the shelf
  46. What dosage regimen were you using. What mechanisms behind theanine would cause this
  47. 200-500mg once daily. I’ve taken it shortly before (an hour or two before intimacy) and have found that I don’t perform optimally during the course of the night. My last two engagements start off sup par. It’s only into the next morning that things start working again. Erections aren’t as full and it’s harder to maintain as well.
  48. 200mg is the max dose per day, i thought. I was thinking of doing 200mg suntheanine 3x a week but not sure
  49. I think theanine is good for social outings or stressful events eg. exams; public speaking etc. I’m just going to avoid taking it on days when I know I’m going to be intimate.
  50. Did you note improved digestion, anti histamine benefits. Supposedly its anti histamine and reduces gut serotonin
  51. If I am getting reduced hypersexual response from peating in-general, what would you suggest I take / adopt?
    The problem is that GABA-agonists also leave me low eenrgy, and I'struggling with energy.

    I have both anxiety and low energy. What should I take to feel both energetic & relaxed?
  52. I can't give medical advice, and that's a difficult question to answer. Hypothyroidism tends to increase anxiety and also symptoms of fatigue, bringing about a state of paralysis. Supplementing thyroid hormone would correct the deficiency, but some combinations of stimulants and depressants might have overlapping effects: progesterone in vitamin E administered together with sugared coffee, for instance. Higher dosages of aspirin have effects resembling that of low-dose fluoxetine (Prozac).