Tyrosine supplement Phenylalanine benefit and side effects, risk, danger – The role of phenylalanine in health improvement, available as 250, 500 and 750 mg per capsule
Use these amino acid pills safely since high dosages, more than 500 mg, can cause heart rhythm disturbances and they can cause anxiety

March 1 2017

L Tyrosine is not an essential amino acid since tyrosine can be made from the amino acid phenylalanine. It is converted into dopamine and norepinephrine. Supplementation with either leads to alertness and mental arousal and slight loss in appetite and perhaps mild mood improvement. Phenylalanine and tyrosine are sometimes prescribed as antidepressants, usually in combination with other nutrients and herbs that have mood elevating properties. Some doctors also recommend these amino acids for appetite control. Phenylalanine may trigger the release of an appetite-suppressing hormone in the gut called cholecystokinin. We know people who occasionally take a small amount of these amino acids, such as 100 to 250 mg, in the morning as a substitute for coffee.

Phenylalanine converts into Tyrosine which can convert into L Dopa, then on to Dopamine, norepinephrine, and epinephrine.

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Supplement Facts
L Tyrosine 500 mg

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If you plan to take tyrosine, limit your dose to half a capsule on an empty stomach or a full pill with a meal, until you find out how it reacts in your system.


Tyrosine or phenylalanine, which one works better?
I am wondering if taking tyrosine has different effects on the body than taking phenylalanine, and vice versa. If one is trying to rebuild norepinephrine and not dopamine, but one or the other or both more specifically target norepinephrine?
It is difficult to know exactly how these amino acids, when taken as a supplement, are metabolized in the body and brain since there are many pathways they can follow. There are several variables involved including dosage, absorption from the GI tract, metabolism in the liver, crossing the blood brain barrier, interactions with food, a person’s individual biochemistry and enzyme status, and other factors. Rather than trying to determine on a neurotransmitter level which converts better into norepinephrine or other brain chemicals, the best option is to experiment with each one in different dosages to see which of the two provides a better clinical response. For those who have depression, 5HTP is a good choice to build up more serotonin.

Phenylalanine amine acid supplement
Phenylalanine is an essential amino acid. Inside the body, it is converted into tyrosine, another amino acid.

It is available in three chemical forms: L-phenylalanine, the natural form found in proteins throughout the body; (2) D-phenylalanine, a mirror image of L-phenylalanine that is synthesized in a laboratory; and (3) DL-phenylalanine, a combination of the previous two forms.

Symptoms of phenylalanine deficiency include confusion, lack of energy, decreased alertness, decreased memory, and diminished appetite.

Which amino acid supplement is better to take for alertness?
It’s difficult to say, some people prefer tyrosine, others prefer phenylalanine. The best way to find out is to try each one separately.

Side effects, caution, risk and danger
L Tyrosine side effects can include overstimulation, restlessness, anxiety, and insomnia. Heart palpitations or arrhythmias are potential side effects that occur from high doses. These can occur in sensitive individuals in as low a dose as 200 to 500 mg. Rapid heart beat, even heart palpitations, can occur as a side effect of tyrosine use. Always start with a low dose, such as 200 mg or less, even if it means opening a tyrosine capsule and taking a portion of it. We are not aware of tyrosine supplements causing blood clots or fatty tumors.

Benefit of L tyrosine for depression
L Tyrosine may help some people in their fight against depression, but dosages above 500 mg, in some people, may cause anxiety, restlessness and rapid heart rate. We prefer other supplements for depression, including 5-HTP, SAM-e, St. John’s wort, B complex and fish oils. Some people find the herb rhodiola to be helpful. Two combination products that are helpful for mood, mental clarity, and energy are Mind Power Rx and MulitiVit Rx.

Tyrosine is an amino acid that can be used in the mornings to enhance alertness and focus. Too high a dose can cause side effects such as irritability, restlessness, anxiety, and heart rhythm problems. Some users find that it enhances their mood. N-Acetyl-Tyrosine is an alternative. Less of a dose of acetyl-tyrosine is required to achieve the same effects as tyrosine. A morning dose of 100 to 200 mg of acetyl l tyrosine is sufficient for most people. You have the option to open a capsule of l tyrosine and take a portion.

Combinations and interactions with other natural supplements and natural anti-depressants
SAM-e –  we suggest not taking the amino acid with SAM-e pills the same day. Anxiety is a possible reaction to the combination.

St. John’s wort – overstimulation, anxiety, and restlessness could occur, along with insomnia.

L Tyrosine studies and research review
Lack of behavioural effects after acute tyrosine depletion in healthy volunteers.
J Psychopharmacol. 2005.
In this study, we investigated the effects of brain dopamine depletion, through acute l-tyrosine and phenylalanine depletion, on plasma prolactin, mood and neuropsychological function in 12 normal subjects. In a randomized, double-blind, cross-over design, subjects received two amino-acid drinks separated by a week, a nutritionally balanced mixture (Bal) and on the other occasion a tyrosine and phenylalanine deficient mixture. The plasma ratio of tyrosine and phenylalanine to the other large neutral amino acids decreased significantly on the tyrosine and phenylalanine deficient mixture and there was an increase in plasma prolactin concentration relative to the balanced drink in the seven subjects for whom results were available for both occasions. Acute tyrosine depletion did not alter mood as measured by visual analogue scale ratings, and measures of memory, attention and behavioural inhibition were also unaffected. Our results are consistent with acute dietary tyrosine depletion causing a reduction in brain dopamine neurotransmission but raise questions about how robust or consistent the effects are on psychological function.

Combining with other dietary supplements
Q. I am considering taking N-Acetyl Tyrosine pills (mornings 200mg) and tryptophan (evenings 500mg) for treatment of mild depression and insomnia. I was wondering whether SAM-e can be taken in addition to the N-Acetyl Tyrosine?
A. Much depends on dosage, individual tolerance, food intake, other medicines that you take, age, smoking, exercise patterns, sleep patterns, etc. It is a good idea to first learn how each supplements works by itself before combining. Tyrosine and SAM-e will cause insomnia.


Q. I went to a boarding school for three years where I averaged about 5 hrs of sleep every night. On top of this I was subjected to the physical stresses of mandatory sports, and ever present cold. I think the result is that I became a walking zombie. My awareness and attention drastically suffered, my emotions somewhat froze, and I developed obsessive compulsive disorder. After taking a sufficiently large dose of MDMA, I noticed that I became aware of the world in a way similar to how I had experienced it before boarding school. I concluded that I needed to redevelop my serotonin system, so I started taking 100mg 5htp on a daily basis. I noticed that my mood was better, especially when I took little breaks from it (I was pleased to learn that you recommend this practice). I also decided to experiment with my dopamine system, so I tried n-acetyl-l tyrosine. Immediately, I noticed an improved ability to perceive color. After a lot of trial and error, I found it best to take the n-acetyl-l tyrosine in two daily doses of 75mg. These two supplements have greatly helped, in the depression/anxiety, with which I was recently diagnosed.
   A. Thanks for emailing your interesting story.

Q. I continue to learn from your book, Mind Boosters. It is the one source that I continually return to when exploring nutritional approaches. My question concerns tyrosine supplements. I have recently begun taking Acetyl L-Tyrosine, one 300 mg. tablet in the morning. It seems to increase energy, and even give a little boost in the area of verbal fluency (an area that I am very interested in improving). I seem to “feel like talking” more than I normally would, and the words seem to come a little more easily. However…I’m having a lot of trouble sleeping, even with this small (I think) dosage, I seem to have a “wired” feeling. I would hate to give up the benefits of tyrosine.
A. 300 mg of acetyl-tyrosine is actually, in my opinion, a high dose. Acetyl-tyrosine is probably much more active that tyrosine by itself. The alertness it produces does cause insomnia. A lower dosage may reduce the side effects.

Q. I have read a lot on your web site about the cautions of 5-HTP and would like to ask about whether there are any risks of using l tyrosine in the long-term. For me, this supplement really helps with my mood but I would like to know whether the amino acid is safe for daily consumption at a high dose (12 grams). I do not experiences any side-effects from this amino acid and have not read any reports of toxicity ever occurring from its use.
A. Twelve grams of tyrosine is an extremely high dose. Side effects could include irritability, anxiety,  heart irregularities and perhaps, over the long run, tyrosine could have a pro oxidant effect on certain brain cells, but this is just a hypothesis. Tyrosine seems to be more effective in those whose depression is due to low dopamine levels. It’s probably best to not use one particular nutrient to treat depression for prolonged periods but to alternate different ones such as St. John’s wort, SAMe, 5-HTP, etc. 

Q. Why is it so hard to get l-tyrosine, phenylalanine, and others in smaller doses? Everyone talks about the 500 mgs doses, I personally do much better with the low doses.
A. It seems that the public thinks higher doses are better, and manufacturers respond to this by selling higher dose products, worried that other companies may grab a larger share of the market by selling higher dosage nutrients. Since each person is unique in their requirement, it is okay to open capsules of tyrosine or other nutrients and herbs and take a portion.

Q. I have been taking L Tyrosine for about 7 years to help with central serous retinopathy. However, over the past two year I have suffered terrible insomnia and never made a connection. Thanks to looking at your site and the great information I see the connection. Do you think that the tyrosine 500mg dosage that I have been taking for 7 years is a little to high?
A. We can’t say if the tyrosine is the cause of your insomnia, but it has the potential to cause sleep problems.

Q. Last year after taking Prozac for many years I decided to add L-tyrosine to my daily supplements. I added about 900 mg a day. Soon after that I developed what’s been diagnosed as “tics”. I’m wondering if the addition could have had anything to do with this?
A. It is possible, but we can’t say for sure.

Q. When I take L-tyrosine I seem to have intestinal problems, such as gas and lose bowels. Is this a common side effect with L tyrosine supplement?
A. Tyrosine has many side effects, the most common being irritability and rapid heart beat, but gastrointestinal symptoms can also occur. A lower dose tyrosine may not cause these side effects.

Why is it recommended that tyrosine be taken at least 30 minutes before a meal or 2 hours after a meal?
Tyrosine cannot easily cross the blood brain barrier if there are many other competing amino acids in the blood stream which occur after eating a meal. Therefore, on an empty stomach, tyrosine can be absorbed well and cross the blood brain barrier. However, tyrosine side effects are higher when this approach is taken, therefore a lower dosage would minimize this. Hence, to notice the effects from a tyrosine supplement, one can take a higher amount of tyrosine with food, or a smaller amount on an empty stomach.

Even a small portion of beef contains more tyrosine than most supplements. Why shouldn’t I just eat a burger?
When individual amino acids are taken by themselves, they have a different affect on the body and mind as opposed to taken in combination as a supplement or in food. A dose of tyrosine, for instance, can cause alertness, whereas if the same amount is ingested in beef, it would not cause alertness since it would be mixed with many other competing amino acids.

I have seen an ad for Glycyl-L-Tyrosine. How is it different than tyrosine?
Glycyl-L-Tyrosine is a new one for us. We don’t know much about it and have not seen human studies with Glycyl-L-Tyrosine.

We have become a country that depends on babysitters and sometimes babysitters aren’t so nice. I live in Asia most of the time and find it so refreshing that many of the people that we Americans consider poor and downtrodden are much more intelligent about their health than we have become. Personal responsibility for an individual’s health has migrated to ‘corporations’ that promise that they are taking care of us. I love being aware of my own health and the life I lead. I don’t smoke anymore, but I do juice, take supplements if need be, drink too much wine, exercise, and I PICK MY OWN POISONS! If you get my drift. Wake up America. Thanks again.

I admit that I have a difficult time understanding a lot of scientific articles and technical terms, but I have been treated for breast cancer and am currently NED and taking armidex daily. I was also HER2+ and so received herceptin. I have been using an over-the-counter diet supplement (Xenadrine RFA-1) that contains l-tyrosine. There are 80 mg. per capsule, and I end up taking no more than 4 per day. Should I discontinue this?
This is a decision you and your doctor need to make. It is difficult to know how a product such as Xenadrine or an amino acid supplement such as tyrosine interacts with the other medications.

I am a doctor in Spain and have been taking Neuroreplete wtih 5htp, tyrosine. and have side effects like; libido loss, constipation, occasional tacchycardia and extrasystoles. I relate them to the use of these amino acids since they have started after Neuroreplete use. The dose of tyrosine I take is too high, I guess. ( 1500 mg x 4 ) I am planning to stop them.
Yes, this high dosages can cause cardiac side effects.

Is it true that if you’re taking 5-HTP and T, you need to take proper amounts of cysteine two pills three times a day to prevent depletion of the sulfur amino acid system? I’m taking T and 5-HTP to replenish my brain after about 5 years of being bipolar but am now emotionally intelligent. I would like a second opinion on the following; after taking 500 mg of T before breakfast and 100 mg of 5-HTP after breakfast for 3 weeks, my doctor suggested I increase the doses to 500 mg of T twice a day and 200 mg of 5-HTP (time released) once a day for 3 more weeks. I know that you can build a tolerance to 5-HTP so would taking it for 3 more weeks be ok?
We are not in a position to offer individual advice regarding dosage and timing. Thus far we have not seen any research that would indicate the use of cysteine is necessary.

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Vasaka consists of leaves of the plant Justicia adhatoda

How much more potent is N-acetyl-Tyrosine compared to the same amount of L-tyrosine? I have severe problems with anhedonia and bought the former to try and raise dopamine levels.
It’s hard to say. We have not seen studies comparing the two. In our limited experience, we do find acetyltyrosine to be more potent, but we can’t quantify it easily. You may wish to try them yourself with the same dosage on different occasions to see how they compare.