I will use this topic to ask for a few questions related to L-tyrosine.
1. When talking about supplementation with phenylalanine/ tyrosine/L-Dopa or tryptophan/5-HTP people always note the undesirable conversion of these substances into active compounds (catecholamines, serotonin) peripherally.
What does the word “peripherally” actually mean in a context like this? Is it peripheral nervous system (PNS) or does “peripherally” mean simply “before reaching the nervous system” e.g. the conversion takes place in the digestive tract, blood, liver, adrenal glands etc.?
There are anecdotal reports stating that after consumption of tyrosine heart rate and constriction force are increased slightly and some people find out that tyrosine causes a mildly uncomfortable sensation in the chest for them.
So I wonder, is this a result of tyrosine being converted into catecholamines peripherally (outside the nervous system)? Let’s say in this way, tyrosine is converted to catecholamines in the adrenal glands and then epinephrine and norepinephrine is released into the blood stream causing the heart to increase its pace and power.
Or is the increase in the heart’s work actually a result of tyrosine being metabolized in the nervous system? As excitory neurotransmitters dopamine and norepinephrine is created in the nervous system, the excitement is transferred to the heart by the vagus nerve, therefore the heart pace is increased?
2. Since the peripheral conversion of aromatic amino acids may cause undesirable side effects, some people recommend taking aromatic amino acids with EGCG, which acts as a peripheral aromatic L-amino acid decarboxylase inhibitor, which is thought not to cross the BBB. We should keep in mind that some studies note that EGCG is hepatotoxic in higher concentrations.
So how much milligrams of pure EGCG (since the concentration of EGCG in green tea extracts varies) do you take with your aromatic amino acids?
3. Some people recommend taking aromatic amino acids with vitamin C and B6, stating that these cofactors are needed for the proper synthesis of neurotransmitters, while others completely disagree, maintaining that vitamin C and B6 would cause a rapid metabolism of aromatic amino acids before reaching the nervous system.
So do tyrosine consumers use these cofactors or take tyrosine alone?
4. Since tyrosine is a stimulant, some people find it harder to fall asleep (even if tyrosine was taken in the morning). Some take tryptophan or 5-HTP at night (to balance serotonin with dopamine and assist sleep).
Do tyrosine users consume any GABAergic substances before bed?
5. Everyone is different, so there is a mixed anecdotal experience on supplementation with tyrosine. Some people have been consuming tyrosine for years without the development of tolerance and they still do get those positive effects of tyrosine, while others report getting tolerant to tyrosine quickly. Therefore, as one can’t be too careful, for some people it may be a good idea to cycle tyrosine.
How do you all tyrosine users cycle tyrosine? What alternatives for tyrosine do you use?
I’ve googled the info and searched the topics about tyrosine on this forum, but I still do need some clarification on the consumption of L-tyrosine. It would be nice if someone could share their knowledge.
1. Peripheral conversion of catecholamines occurs primarily in the autonomic nervous system and adrenal medulla, but can also occur in the digestive tract and within the bloodstream. The peripheral effects of catecholamine precursors are mostly due to increased norepinephrine synthesis and release within the perhipheral autonomic system. It's very reasonable to assume that noradrenergic effects within the CNS trigger some of the sympathetic activity, but these effects are greatly lessened by taking tyrosine or levodopa with a PAAD inhibitor. Thus, the somatic side effects are mostly due to norepinephrine synthesis directly within the PNS.
However, levodopa/tyrosine-induced nausea and vomiting are not caused by sympathetic activity. Elevated levels of dopamine in the bloodstream activate the chemoreceptor trigger zone, a toxin detection system in the brain which is located outside of the blood-brain barrier. Normally, blood catecholamines cannot penetrate the CNS, but dopamine can enter the chemoreceptor trigger zone and thus cause nausea/vomiting.
In the case of peripheral serotonin generation, direct stimulation of 5HT3 receptors within the digestive tract is a putative mechanism for causing nausea -- the digestive tract feeds this information back into the CNS through the vagus nerve, and stimulates the nausea/vomiting system within the brain. This causes the subjective feeling of nausea. If the system is activated strongly enough, the vomiting reflex is activated.
2. No clue. I just take low enough doses of tyrosine or levodopa that they don't cause nausea or sympathetic hyperactivity anyway. 2 DopaBean capsules (50mg levodopa) or 2 grams of tyrosine on an empty stomach is my max; any more causes more trouble than it's worth.
3. Some take them with, some take them without. A good daily multivitamin ought to have your B6 and C needs covered anyway, though.
4. Yes, some do that. I personally did not find this necessary, as morning doses wore off long before bedtime. But if I had found it necessary, I would have taken an anti-noradrenergic drug instead of a GABAergic drug, because GABA did not cause the insomnia in the first place. Catecholamines did, and I prefer to solve the original imbalance instead of covering it up with a new imbalance. Clonidine, guanfacine, and tradozone are effective alpha-antagonizing sedatives. (Actually, clonidine and guanfacine are alpha agonists, but they're alpha-2 agonists, which means they're sympatholytic sedatives. They indirectly antagonize alpha-1, beta, and dopamine systems.) I've used them before when I took ritalin too late at night and I needed to cancel out the stimulation in order to sleep.
5. I never used tyrosine or levodopa with any regularity. I treated them as "emergency" drugs for when exhaustion or illness was threatening my ability to work. For ADHD, anxiety, and depression, I used drugs which are approved for chronic treatment of those conditions, and also CBT.
LongeCity
