Phenylalanine supplement benefit, and side effects of this amino acid, safety issues and adverse reactionsby Ray Sahelian, M.D.
September 20 2016
Phenylalanine is an essential amino acid. Inside the body, it is converted into tyrosine, another amino acid. Tyrosine is then used to produce dopamine and norepinephrine, both neurotransmitters. All of these elements are important because of their relationship to the central nervous system.
Phenylalanine is available in three chemical forms: L-phenylalanine, the natural form found in proteins throughout the body; D-phenylalanine, a mirror image of L-phenylalanine that is synthesized in a laboratory; and DL-phenylalanine, a combination of the previous two forms.
The body converts phenylalanine into tyrosine, another amino acid essential for making proteins, certain brain chemicals, and thyroid hormones. Symptoms of phenylalanine deficiency include confusion, lack of energy, decreased alertness, decreased memory, and diminished appetite.
Source Naturals - DLPA, 375 mg, Tablets
DL-Phenylalanine is a 50/50 mixture of the D- and L- forms since phenylalanine is one of the few amino acids that can be utilized in its D- form.
Warning: Not to be used by phenylketonurics, pregnant or breastfeeding women, or with antidepressants drugs such as MAOI's or SSRI's. If you have chronic high blood pressure, consult your health care professional.
Mind Power Rx has a wonderful balance of brain circulation agents and neurotransmitter precursors with powerful natural brain chemicals that support:
DL- Phenylalanine - 375 mg each pill
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Memory and Mood
Alertness and Focus. The ingredients are: Ashwagandha, Bacopa, Fo-Ti, Ginseng, Gotu kola, Mucuna pruriens, Reishi, and Rhodiola. The nutrients and vitamins in Mind Power Rx include Acetyl-l-carnitine, carnitine, Carnosine, Choline, DMAE, Inositol, Methylcobalamin, Pantothenic acid, Trimethylglycine or TMG, tyrosine, and the vasodilator Vinpocetine.
Serving Size: 2 Tablets
Servings Per Container: 60
Amount Per Serving
Daily Value not established
Twinlab, DLPA, 500 mg, 60 Capsules
I don't consider this amino acid supplement to be a smart pill. There are many other herbs and nutrients that I like for mental enhancement, for instance acetylcarnitine, ginkgo, bacopa, and others.
There may be a health danger in high doses. Some of the side effects include anxiety, restlessness, rapid heart beat, and potential heart palpitations. Some people could have elevated blood pressure.
About two months ago I was in my third week of quitting smoking. I was still feeling really depressed and down and I started looking for something to help me. I came across an article about L-Phenylalanine and how it would help me quit easily. I started taking 1,500 mg Now Foods brand pill a day. The first day I felt amazing. Energy, clarity, focus, etc. It's like I was back to smoking, but I hadn't started back up yet. I continued taking it for a week. One pill a day. That energy and focus quickly left, and I then started to feel some low level anxiety building, such as constant worry and a little derealization at times. I chalked it up to me quitting smoking. How wrong I was... In my second week, I was taking two 500 mg pills a day, spaced out throughout the day. I did this for about a week, and the anxiety got worse, but I attributed it to quitting smoking (again) and the fact I was about to start a new job. Soon after, all hell broke loose. I started pacing back and forth, and my thoughts wouldn't stop. It was overwhelming. I started crying and I felt like some sort of doom was impending. I exercised to tire myself and went to bed, hoping it would all go away. It did not. The next day, I went to the Emergency Room. It felt like I was losing my mind. I was given Ativan for anxiety, a 5 day supply and told to follow up with my doctor. the next day, it was worse. I should add I stopped taking the L-Phenylalanine once I realized this is what caused it. I went back to the ER, this time in full blown panic mode. Shaking, crying, cold chills, heart palpitations, doom, death, etc. It was the scariest moment of my life. Over the next week, I got better (thanks to the Ativan), however after my supply ran out, I went back to having panic attacks, although less severe. Over the next 3 weeks, I progressed each day, until 4 weeks later I felt completely depersonalized. I decided to have a few glasses of wine to ease my mind. Big mistake! The anxiety attacks started back again. Vomiting, crying, heart palps, cold chills, doom, etc. I went back to the ER, and was given a shot of Ativan and nothing else. I'm now almost 3 weeks from that point, so we're looking at almost 7 weeks total since the first ER visit. Currently, I'm much calmer, although I still have to actively manage my symptoms, such as minor heart palps, cold chills, and chest pain. Right now, I'm only taking a multi vitamin, magnesium, Fish oil, and B complex. It seems as though I'm still progressing, I'm just so sick of this and want it to be over. Can you give my any advice or help with this? Did the L-Phenylalanine cause any permanent damage?
A. I doubt that it caused permanent damage. Anti anxiety natural supplements should provide relief.
DL- Phenylalanine - 375 mg each pill
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A rare metabolic disorder called phenylketonuria occurs in people who are missing an enzyme that is needed to properly metabolize phenylalanine. Symptoms of PKU, which tend to appear between three and six months of age, include eczema, developmental delay, an abnormally small head, and hyperactivity. If it is not treated before three weeks of age, PKU can cause severe, irreversible mental retardation. In the United States, newborns are tested for PKU during the first 48 to 72 hours of life.
Do you know of
anything natural that will help or cure PKU? It is for my 8 year old son? He has
had this disease since birth.
I have not studied the topic of natural treatment of PKU in any detail and do not have a solution at this time but I am looking our for new research.
Several forms include dl, d, and l phenylalanine. We recently had a question regarding these forms.:
Q. I noticed the Source Naturals
phenylalamine product is the DL-phenylalanine version. You mention there are
three kinds, the L, the D and then the DL-phenylalanine. Would you be able to
tell me specifically what issues each of these targets? I have read
Phenylalanine can help with things ranging from chronic pain to anxiety,
depression, pms, so I would be interested to know what form addresses what
A. Phenylalanine is an essential amino acid. L-Phenylalanine (LPA) is an electrically-neutral amino acid, one of the twenty common amino acids. L-Phenylalanine that is ingested is mostly hydroxylated to form the amino acid tyrosine, which is used in protein synthesis. D-phenylalanine (DPA) is the mirror form of L-phenylalanine and does not participate in protein biosynthesis although it is found in proteins. The biological activity of D-phenylalanine is not as well known as L-phenylalanine but is thought to have pain reducing properties or perhaps it enhances the pain reducing ability of pain killers when taken together. D-phenylalanine may also have mood lifting potential. DL-Phenylalanine is a combination of D-phenylalanine and L-phenylalanine and is promoted for mood lifting and pain reducing abilities. Clinical research in humans is quite limited and thus the anti-depressant and anti-pain role of phenylalanine has not been well-evaluated.
Phenylalanine in food
L-phenylalanine is found in foods that contain protein such as beef, poultry, fish, milk, eggs, dairy products, soy products, and some nuts and seeds. D-phenylalanine is synthesized in the laboratory and not found in food.
IUBMB Life. 2013. Phenylalanine
hydroxylase: function, structure, and regulation. Mammalian phenylalanine
hydroxylase (PAH) catalyzes the rate-limiting step in the phenylalanine
catabolism, consuming about 75% of the phenylalanine input from the diet and
protein catabolism under physiological conditions. In humans, mutations in the
PAH gene lead to phenylketonuria (PKU), and most mutations are mainly associated
with PAH misfolding and instability. The established treatment for PKU is a
phenylalanine-restricted diet and, recently, supplementation with preparations
of the natural tetrahydrobiopterin cofactor also shows effectiveness for some
patients. Since 1997 there has been a significant increase in the understanding
of the structure, catalytic mechanism, and regulation of PAH by its substrate
and cofactor, in addition to improved correlations between genotype and
phenotype in PKU. Importantly, there has also been an increased number of
studies on the structure and function of PAH from bacteria and lower eukaryote
organisms, revealing an additional anabolic role of the enzyme in the synthesis
of melanin-like pigments. In this review, we discuss these recent studies, which
contribute to define the evolutionary adaptation of the PAH structure and
function leading to sophisticated regulation for effective catabolic processing
of phenylalanine in mammalian organisms.
Q. Why is it so hard to get tyrosine, phenylalanine, and others in smaller doses? Everyone talks about the 500 mgs doses, I personally do much better with the low doses. Is it possible that lot of people would do better with the lower doses, as you talk about in your Mind Boosters book?
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.
I have recently started researching DLPA and tyrosine and am wondering if there
is any real reason to take BOTH, or if it is generally an either/or thing. I
currently take tyrosine and iodine, along with high pot. liquid multi vit/min.,
essential fatty acids etc. I have a thyroid problem and my naturopath has me on
tyrosine and iodine, but because I am pretty overweight I was looking into DLPA
and am confused by the frequent references to take DLPA and tyrosine TOGETHER,
when DLPA will just be turned into tyrosine anyway. Is there another use for DLPA, or is it always turned into tyrosine? And if it is always turned into
tyrosine, why bother with both? And if only one should be taken at a time, which
DLPA does convert into tyrosine, but it can be metabolized in a different direction, too, including phenylpurivic acid and other metabolites. I personally don't see the need to take both tyrosine and phenylalanine. As to which one to choose, the best way is through trial and error since there are blood studies or other tests that can be done to find out which supplement will provide better results.
Q. In the last issue
of your newsletter you talk about the side effects of aspartame and you mention
that phenylalanine is one of its ingredients. Is phenylalanine dangerous? can
phenylalanine cause cancer?
A. A Phenylalanine supplement in high doses may cause heart rhythm abnormalities and anxiety. Long term studies are not available to tell us whether phenylalanine supplements taken for prolonged periods cause cancer.
Q. Can one take
phenylalanine DLPA and L-Tyrosine at the same time? Can one take DLPA,
L-Tyrosine, and 5-HTP at the same time?
A. Firstly it is important to find out the dosage of DLPA that works for you without side effects, and then separately find out the dosage of tyrosine that works for you without side effects. If you combine both DLPA and tyrosine, the dosage of each should be about half of what was appropriate for each one separately. As to your second question, reactions to supplements become difficult to predict when more than 2 are used. Hence, adding 5HTP to dl phenylalanine and then adding 5HTP may be tolerated or cause unpleasant side effects depending on the person using it, other supplements used, other medications that might be taken together, a person's overall health, and most importantly the dosages that are used.
I read that if you take supplemental Tyrosine,
you should make sure that it also contains Phenylalanine or take supplemental
Phenylalanine. It also said that Phenylalanine must be present with Tyrosine in
order to produce Tyrosine in the body. Do you agree? Or is it okay to just take
Depends on the reason these supplements are being used. In most cases there is no reason to use both, tyrosine works well by itself and there is no need to take both tyrosine and phenylalanine. But each condition is different, each person is different, and the dosage makes a significant difference.
I have been reading
about phenylalanine and dopamine but there's not a lot of research or info
regarding the use of d l phenylalanine with ssri's. i do take a ssri medication.
why do you not recommend them both? also, I have heard that phenyl is not good
for anxiety, but i suppose that would be dose related. maybe l-tyrosine would be
a milder choice. now that i remember, the reason i stopped drinking diet drinks
was it seemed to make me feel very strange, although i cannot say for sure that
was the cause. anyway, my doc wants to put me on a dopamine agonist to increase
my dopamine but i would like to try something natural like maybe nadh or
l-tyrosine or something similar. As always, i understand you cannot comment on
psychiatric conditions, but if you wanted to raise your dopamine levels
naturally, where would you start?
Rather than focusing on what specific brain chemical to increase, it is best to have a wider viewpoint and treat overall symptoms of a condition. However, you can find dopamine increasing supplement information.
On your web page you
mention that Phenylalanine converts to L-Tyrosine, which you further explain
converts to L-Dopa, Dopamine, Norepinephrine, and Epinephrine. So, I apologize
if the following questions may sound rather ignorant, if Phenylalanine converts
into Tyrosine, which then converts into the other aforementioned
neurotransmitters, why would a person not just use a Phenylalanine supplement,
rather than a Tyrosine supplement? I suppose another approach to asking this
might include a request for clarification regarding your comment that
"(phenylalanine)...can be metabolized in a different direction...including
phenylpurivic acid and other metabolites." Essentially, what does this statement
mean, and what are its potential implications, particularly for the person who
might be considering supplementation with either amino acid? Thank you in
advance for any additional light you can shed on this subject.
When a phenylalanine supplement is taken, it is partially converted into tyrosine and partially into other substances. The tyrosine is further converted into L dopa and other substances, therefore the effects from each amino acid or other substances down to road of metabolism somehow overlap but have differences which do no make them exactly equivalent in overall effects. The best way to know which supplement works best is to try it by itself for a few days.