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I thought that aspartame is poisonous because it contains phenylalanine? If that is so, then why is it essential for human nutrition and why are not more people aware of it?

Aspartame is not generally poisonous. It is poisonous to phenylketonurics because it contains phenylalanine. I doubt that phenylalanine is 'essential for human nutrition', even though it may be an 'essential amino acid'. The two are not equivalent. JunkCookie 23:45, Aug 6, 2004 (UTC)
Maybe you should add that? Certainly, more people can be confused as well. Anonymous 21:35, Apr 17, 2006 (UTC)

Source of data[edit]

I found the information for the melting point, boiling point, and density of phenylalanine here: KBi 04:36, 12 July 2005 (UTC)

Diet Coke![edit]

Can someone add information as to food types these amino acids are added and effects human well being? Is it cancerous?

It's almost like an allergy to the acid. You either are, or you aren't allergic. Don't worry, chances are if you don't have a problem with it currently, then you're fine. But just to be on the safe side, I would try to consume as little as possible. It contains formaldehyde(sp). I personally find that repulsive, considering it is used to preserve dead bodies.

It contains Aspatame which is metabolised to %50 Phenylalanine, %40 Aspartic acid and %10 Methyl alcohol which is metabolised to formaldehyde —The preceding unsigned comment was added by The Right Honourable (talkcontribs) 08:34, August 21, 2007 (UTC).

I dont think its cancerous, I think its basically an amphetamine.... which means it likely causes heart disease or other heart problems Havabighed (talk) 06:52, 5 July 2012 (UTC)

Dear Havabighed, no, it is not basically an amphetamine, it is nowhere close to being an amphetamine. Every living cell needs and uses phenylalanine as it is used to construct proteins. Your body - apart of being largely made of water - contains proteins, of which phenylalanine is one of the 20 amino acids to make them. 11/2012 - anon. — Preceding unsigned comment added by (talk) 20:10, 27 November 2012 (UTC)

If you eat any type of protein, you are most likely consuming phenylalanine. Aspartame metabolism leads to the presence of phenylalanine which is not in and of itself a problem unless you are a person who does not contain the enzyme to degrade phenylalanine. If you have no idea what I'm talking about then you're fine, you don't have that problem; you would know. Other than that Diet Coke is just doesn't taste there's that. (talk) 00:43, 10 February 2014 (UTC)

Some form of lifting going on (not sure which direction) and objectivity questioned[edit]

This site:

has the exact same phrasing of

"too much Phenylalanine is a neurotoxin and excites the neurons in the brain to the point of cellular death to the brain cells. ADD/ADHD, emotional and behavioral disorders can all be triggered by too much Phenylalanine in the daily diet of the human body."

It looks like the person is billing herself as an "expert" on this topic, but is also selling a detox program. I am guessing that she didn't lift from wikipedia for her own text... which means it happened the other way around.

If something like that is going to be claimed, we need something more than a detox sales site to back it up for sure.

11/2012 - I have to add, that the site author of is an idiot who loves to see her photo too much. She tries to deceive the gullible. The proofs are many, for example she quotes someone that 'cancer cells can not survive without phenylalanine and aspartame is 50% phenylalanine!!!' -- no living cell can survive without phenylalanine. That includes bacteria, moulds, birds, cancerous and non-cancerous tissues, etc. - anon.

I concur. This is an encyclopedia, you cannot have what looks like a factual reference to something that does not have any studies, medical journals or anything of that effect listed. If a view was to be presented with regards to Aspartame, then post it there, not at this page.
At second thought, that link is completely irrelevant to the discussion, and I believe it is a blatant plug for a commercial product, i'm going to edit that out since it is not relevant. Imagine someone plugging a radiation treatment plan on the Nuclear Weapons page
--Popoi 19:41, 2 January 2006 (UTC)

Someone has again added this spurious statement. If you, the author of this text, are reading this: please provide a legitimate citation. That website is not legit. It is most definitely untrue that Phe can cause such disorders. One would think that by increasing phenylalanine intake, one could thereby increase dopamine production. Unfortunately, this logic is flawed, as the human body has numerous mechanisms which prevent this from happening. If we didn't have such mechanisms, we would all suffer a form of psychosis not unlike that caused by excessive amphetmine intake (amphetamine psychosis), or MAOI poisoning. Fuzzform 20:40, 20 February 2006 (UTC) -- The ADHD link may be more related to the actual nutrition -- remember, artificial sweeteners excite the sweet taste buds in the mouth and similar sensors in the stomach and beyond and these effects can be caused in sensitive people with aspartame, cyclamate, saccharine, sorbitol. Additionally, young children on caffeinated drinks will be hyperactive without sugar or sweetener too. - 11/2012, anon.

Furthermore on the "too much Phenylalanine is a neurotoxin and excites the neurons in the brain to the point of cellular death. ADD/ADHD, emotional and behavioral disorders can all be triggered by too much Phenylalanine in the daily diet." Just a couple comments... ADD/ADHD is medicated by giving people amphetemine salts (i.e. adderal), which happen to work by blocking the reuptake of dopamine and norepinephrine into the presynaptic neuron and increasing their release from the presynaptic neuron into the extraneuronal space. So, if it were possible that phenylalanine excited neurons, which I'm most positive it doesn't unless converted to a catecholamine (also see fuzzform's insightitful comment above), then it could be speculated that it would decrease ADD/ADHD not increase it. That is, unless some time during developmental gene imprinting, excess dopamine caused by excess phenylalanine (doubtful) caused a down regulation of DA receptors in the prefrontal cortex. Niubrad 02:54, 23 January 2007 (UTC)

Should I or Shouldn't I[edit]

My personal trainer advised me to start drinking protien shakes and recommended SciTech Nutrition Whey Best. As I sit here today reading the label I noticed it says it contains "*Phenylketonurics: Contains phenylalanine" So I looked it up on the internet, found this web site and want to know...what do you think, should I drink it? Is it safe? -- 23:15, 25 April 2006 (UTC)

  • Phenylalanine is present is in a lot of things. Check out a can of cola. The handy thing about commercial food products is that if there's something dangerous in it, either it's not understood as dangerous yet (in which case everyone will tell you it's safe) or the FDA wouldn't have allowed it in the first place (or whichever governing body controls food safety on your continent). You'll be fine, unless you OD on it; in that case, as in if you intend to drink vast quantities of these shakes, you should probably talk to your doctor to get a more considered medical opinion. --User:Firien § 10:41, 26 April 2006 (UTC)

The warning "*Phenylketonurics: Contains phenylalanine" is there for people who are Phenylketonurics, that is those who have PKU and are unable to process phenylalanine. These people are often on resrictive diets that don't have this amino acid. The warning is for them so that they are aware that they cannot consume the product. Most foods with that label have aspartame in them, which in the body is changed to phenylalanine which is poisonous for those who are have PKU, but not necessarily anyone else. --Moonshire 16:45, 11 May 2006 (UTC)

This last paragraph is possibly what many people will be looking for when they search on phenylalanine. Could it be included at the top of the main article? AlexFoster 01:33, 29 August 2006 (UTC)

Whenever you eat protein you'll break it up in your stomach and absorb the "infamous phenylalanine". You need it! Aaadddaaammm 07:19, 8 October 2006 (UTC)

Merge with DL-Phenylalanine[edit]

I vote a definate yes to the merge. Aaadddaaammm 07:20, 8 October 2006 (UTC)

support as well. I suppose if no one has chimed in further in a few days it should be fine to merge. Radagast83 05:22, 3 November 2006 (UTC)
Weak support, if it is clear in the resulting article, that D-Phenylalanine is the other isomer, hence, it should have an own section, not merged into all the other sections. Otherwise this will be confusing. --Dirk Beetstra T C 08:32, 3 November 2006 (UTC)
Support as long as it has it's own section and is searchable. Many people will just search for DPLA, so the page will need a redirect also.--Travisthurston 17:38, 9 November 2006 (UTC)
Support merging, especially if DL-Phenylalanine is cleaned up in the process. – ClockworkSoul 20:25, 15 November 2006 (UTC)

Now that DL-Phenylalanine redirects here, I guess I'll go ahead and remove the tag. --Michael 19:45, 7 December 2006 (UTC)

Question about generalization:[edit]

The article asserts that "... food products, all of which must be labeled: "Phenylketonurics: Contains phenylalanine." As I have yet to see this labelling in Canada (but would like to), I'd value some clarification as to the geographical scope of the statement. Which governments require this labelling? I.e.: "Says who?" Ve3wtj 19:00, 15 February 2007 (UTC)

Uninformative "dietary aspects"[edit]

I removed this section because it was completely uninformative:

Phenylalanine is contained in most protein-rich foods. Especially good sources are dairy products (curd, milk, cottage cheese), avocados, pulses and legumes (particularly peanuts and lima beans), pistachios, almonds, seeds (piyal seeds), leafy vegetables, whole grains, poultry, fish, other seafoods, and some diet beverages.

It used the shaky formulation "good sources" and named some foods low in protein like leafy vegetables where even the fraction of the protein consisting of phenylalanine residues is lower than in some protein rich sources which are not listed. Icek 22:56, 9 August 2007 (UTC)

This is the information I was after. It would be usefull if this was rephrased and placed into the article in a clearer way. Also the layout is a little strange if you're after its uses.. you have to read the section about Phenylketonuria before you find out that it is used in sweetners. (talk) 08:54, 23 June 2008 (UTC)


note that this form IS found in nature and is an active moiety in some antibacterial agents such as polymyxin B in which it and d-leucine (in a 7 membered ring including the noted (d)-Phe-Leu component) comprise a hydrophobic binding region of the bacterial agent when binding to gram negative bacteria —Preceding unsigned comment added by Chemical Assassin (talkcontribs) 11:58, 27 July 2008 (UTC)

"Contains phenylalanine"[edit]

Perhaps it's relevant to put in the article, but I noticed my drink "Mike's Hard Mango Punch" has a this rather unique notice in the fine print "Phenylketonurics: Contains Phenylalanine." I read a lot of labels, and this one is new to me. -Legaia (talk) 03:02, 23 August 2009 (UTC)

Laxative Effect[edit]

I just want to add that this phenylalanine as a laxative effect and too much consumption of it may cause diarrhea — Preceding unsigned comment added by (talk) 20:19, 25 June 2011 (UTC)

Heading Other Biological Roles seems out of place[edit]

Look at "Other Biological Roles". Other implies there was a biological role stated and now this section contains more. However, there are no biological roles mentioned above other than brief mention of being a precursor to Phenylethylamine (shouldn't that be in the same section as the precursor to Tyrosine?). I would assume that L-Phenylaline has more activity in human (or other) bodies than just being a precursor to L-Tyrosine and PEA. [1 comment edit for clarity] (talk) 02:40, 15 April 2012 (UTC)


I think there is a lot of unsupported speculation in this article about supplementary use of phenylalanine. What do you guys think? /Jimmy — Preceding unsigned comment added by (talk) 17:05, 16 September 2012 (UTC)

"in large quantities, interferes with the production of serotonin" - wait, what?[edit]

Seriously, this is very, very vague. Does it mean it decreases serotonin production? Or increases? Or does it change serotonin re-absorbtion? If it decreases serotonin production for real, is it possible to use it as an serotonin-syndrome antidote?

And last: why is the statement connected to the passage of blood-brain barrier? Is it in any way related?

Love, the best to you and your family, anon. (talk) 20:16, 27 November 2012 (UTC)