Why Did The FDA Recall L-Tryptophan In 1989?

Concealing The Truth With Politics

L tryptophan received a lot of media attention in 1989. Why? Because numerous people fell gravely ill after taking tryptophan supplements.

After a huge number of studies examined the issue, it turned out that the culprit was product contamination of supplements containing the amino acid, all of which originated from a single manufacturer. Yet shortly thereafter, defying any sound reasoning, the FDA issued a general ban on tryptophan supplements, regardless of who manufactured the products.

The truth about the FDA and its ban of L tryptophan is that the federal agency played politics, namely favoritism, that is, it protected the interests of specific corporate groups the FDA has unholy connections with.

The Tryptophan-Associated EMS Disaster

-Caused By A Single Manufacturer Of L-Tryptophan

In 1989 some nutritional supplements containing L-tryptophan caused serious harm such as eosinophilia-myalgia syndrome (EMS) which left at least 1,500 people permanently disabled and resulted in about three dozen subsequent deaths upon the consumption of the amino acid (Hill, et al., 1993; Druker, 2001; Official US Government FDA website, accessed July 2012).

L tryptophan-associated EMS is a conglomerate of connective tissue disorders, hallmarked by flu-like symptoms, epitomizing an inflammatory-allergic state (eosinophilia), especially with severe pain and weakness in muscles and joints (myalgia).

Various tests found out later that these L tryptophan dietary supplements were contaminated with dozens of substances (Hill, et al., 1993), including a topically-used antibiotic which is toxic for ingestion (Barnhart, et al., 1996). The cause of adulteration was traced unmistakably to a single supplement manufacturer in Japan, Showa Denko K. K. (Slutsker, et al., 1990; Hill, et al., 1993; Back, et al., 1993; Henning, et al., 1993; Mayeno & Gleich, 1994; Kilbourne, et al., 1996).

In scientific experiments of several different “brands” of L-tryptophan, only the Showa Denko tryptophan was clearly and causatively linked to EMS (Kilbourne, et al., 1996).

Tryptophan-EMS... Not The Usual Case Of Product Contamination

-What US Health Authorities Failed To Acknowledge: The Obfuscation Of The True Cause

In the early 1980s bacterial fermentation began to replace chemical synthesis as the method to produce amino acids (Sidransky, 2001). Bacteria are grown and cultivated in large containers to foster tryptophan synthesis. The supplement nutrients are then extracted from the microorganisms, purified, and finally processed into nutritional supplements.

In a research article entitled The Skeleton In The GMO Closet -Did Genetic Engineering Cause The Tryptophan-EMS Disaster Of 1989? by award-winning journalist Ingeborg Boyens she claimed the disaster was caused by the introduction of genetically engineered (GE) bacteria which were used, for the first time, in the manufacturing of the nutritional supplement by Showa Denko K. K. to increase tryptophan formation and thus product output (Boyens, 1999).

Unfortunately, the genetic modification of bacteria resulted in the inclusion of several toxic contaminants into the tryptophan products.

(The technology of genetic modification -that creates GE foods, also known as GMO (genetically modified organisms) foods- involves the forceful, artificial insertion of genetic material amongst different species of animals/microbes/plants, leading to numerous mutations, and the introduction of new, untested toxicants, such as allergens and carcinogens (Smith, 2012). The outcome is systemic inflammation in the body which raises the risk of allergies, autoimmune diseases, digestive disorders, diabetes, cancer, heart attacks, Alzheimer's Disease, and many other illnesses (Smith, 2012).)

Boyens reported that:

“According to U.S. law, the company was allowed to sell the L-tryptophan produced in gene-spliced bacteria without any safety testing because it and other firms had been selling the supplement produced in non-genetically engineered bacteria for years without ill effects.” (Boyens, 1999)


“[...], this seemingly minor tinkering apparently produced a toxic brew.” (Boyens, 1999)

Another study noted that there was a strong correlation between EMS cases and L tryptophan supplements from a batch of products where less filtering of the new bacteria was performed in one of the purification steps (Belongia, et al., 1990).

One of the contaminants in particular, peak E or EBT, seemed to be strongly associated with the harm caused by supplemental L tryptophan tainted with impurities (Takagi, et al., 1995; Zangrilli, et al., 1995; Buss, et al., 1996; Saito & Miyamoto, 1996).

However, the Japanese company denied that GMO were the cause of the tryptophan eosinophilic myalgia disaster, but that it was other non-GE-related changes in the production of the tryptophan supplements which led to contaminated, harmful batches of the products (Boyens, 1999).

In other words...

Showa Denko wanted the public to believe that it was a simple case of bad manufacturing, rather than of genetic engineering.

Showa Denko destroyed all the evidence concerning the details of the manufacturing of the L tryptophan supplements so that even an inspection of the facility by the US FDA produced zero relevant data, and the FDA's repeated requests for samples of the altered bacteria were refused by the company every time (Boyens, 1999).

Other investigations (e.g., Crist, 2005) unearthed data showing it was the FDA that displayed a disinterest in getting the GMO-tainted L-tryptophan samples.

Apparently, the FDA kept quiet for a long time about their knowledge of the involvement of GE bacteria, probably to protect the powerful GMO industry (Boyens, 1999).

Further evidence of the Showa Denko-FDA cover-up came from an extensive, independent investigation by William E. Crist, spanning over several years.

Crist documented that...

... Showa Denko had used GE bacteria in their L-tryptophan production as early as 1984 (which explains the hundreds of supplemental tryptophan-EMS cases prior to the 1989 disaster, using Showa Denko products), and, that...

... the FDA had knowledge about the company's prior use of GMO tryptophan supplements, using different GE strains than those responsible for the 1989 incident (Crist, 2005).

Boyens again:

“The FDA had learned as early as November 1989 that the company [=Showa Denko] had genetically engineered its bacteria. However, the agency neglected to reveal the fact until August 1990, when it was forced to respond to an article in Newsday.” (Boyens, 1999) [explanation & emphasis added]

Testimonies from public hearings by FDA officials reveal that the FDA knew that the most likely culprit was GE L-tryptophan but used the contamination tragedy to deceptively put the blame on the “dangers of supplements” (Druker, 2001).

Steven M. Druker, JD, pointed out that:

“Not only was the agency aware of uncertainties within its own ranks, it also knew there was considerable disagreement about the safety of genetically engineered foods in the scientific community at large.” (Druker, 2001)

[Aside the L tryptophan incident, the FDA has a rather ominous history of overlooking and denying the warnings of its own scientists, primarily to protect big corporate industries, such as mainstream medicine -addressed in my article "Tougher Supplement Regulation: A Necessity Or Politics?" (see 'Recommended next page(s)' below)]

Ingeborg Boyens, commenting on the L tryptophan-EMS epidemic of 1989-90, concluded with:

“It was never definitively determined if the toxic assault had been caused by slipshod production—a consequence of Showa Denko cutting back on the level of its filtration—or on genetic engineering gone wrong. More than two hundred scientific studies tried to determine what happened.” (Boyens, 1999)

Crist was more firm in his conviction about the cause of the L-tryptophan tragedy:

“The whole question surrounding Showa Denko's use of GE bacteria appears to have been downplayed or dismissed outright by researchers and government agencies, especially here in the United States—where the biotech industry would stand to lose the most if GE was implicated in, or linked to, a major epidemic like EMS.” (Crist, 2005) [emphasis added]


"[...] US scientists and government regulators appear to have used the same tactic as the implicated manufacturer [=Showa Denko], namely, that the issue of genetic engineering is not something to be disclosed outside (to the public). Instead, they offer a vague explanation that the contaminants linked to the EMS tragedy were caused by changes in the manufacturing process." (Crist, 2005) [explanation & emphasis added]

The Crux Of The L-Tryptophan EMS Incident

-Product Adulteration (With GE Bacteria), Not Innate Side Effects Of Dietary Supplements

In the article Health Risks From Dietary Supplements -Contaminated Supplements I pointed out that in most cases of (more) serious side effects of nutritional supplements it usually is product adulteration (or instances of overdosing), rather than integral toxicity issues of supplement ingredients, that is responsible for the harm.

The L-tryptophan associated EMS tragedy of 1989 was too, ultimately, a matter of supplement contamination, whether it was due to low-quality manufacturing or, and much more likely, due to the introduction of GE bacteria and their toxic by-products, rather than a safety matter with the actual ingredient in and off itself because that is the customary scenario with nutritional supplements and side effects.

Although, among all of the amino acids, L trypthopan does seem to have an inherently higher, rather serious, toxicity profile that should not be neglected (I discussed this in Tryptophan Side Effects: L-Tryptophan Is Far From Harmless). The GE tryptophan may have exacerbated "innate" L-tryptophan toxicity.

For example, I think it isn't far-fetched to assume that some of these foreign GE substances in the tainted L tryptophan supplements responsible for the 1989 incident may have unfavorably altered certain metabolic pathways of L-tryptophan, thus increasing poisonous tryptophan metabolites. And conceivably, vice versa, inflammatory L-tryptophan degradation products may have elevated the toxicity of GE tryptophan.

Maybe the acuteness and severity of poisoning with GE L-tryptophan supplements was largely the result of the synergistic GMO interaction with an amino acid deemed as one of the fundamentally most toxic. On the other hand, the interaction of GE pollutants with other amino acids and other types of nutritional supplements (or foods), may not become noticeable immediately or in severe (initial) form, hiding the connection and its true danger.

However, the reality that proportionally few people experienced serious harmful acute L tryptophan side effects, such as EMS, before the 1989 incident and after it had been addressed, supports the notion that it was primarily a problem of supplement impurity (on behalf of one manufacturer using the GMO manufacturing method).

Although some health experts erroneously claimed that before the 1989 disaster no tryptophan eosinophilic myalgia cases had been documented in the scientific literature there existed some tryptophan-associated EMS victims (Strongwater, et al., 1990).

Prior to 1989, a few EMS cases had also been found in conjunction with non-tryptophan nutritional supplements, and in one occurrence there was no ingestion of supplements (Clauw, et al., 1994). In all of these events it suggested that some type of pollutant caused damage to the liver, resulting in EMS (Clauw, et al., 1994). Nearly all examples of EMS, however, implicate L tryptophan supplements (Kilbourne, et al., 1996).

Similar contaminants as found in the tainted tryptophan-associated EMS incident of 1989 were also found in some melatonin nutritional supplements (Williamson, et al., 1998). The consumption of large doses of these adulterated melatonin products led to certain EMS-type symptoms in some people (Williamson, et al., 1998).

Since the body converts L tryptophan into 5-hydroxy-L-tryptophan (and then to serotonin), in the consumer's mind, presumably, the metabolic intermediate was regarded as an attractive alternative to tryptophan after its recall (Das, et al., 2004).

But after the 1989 event, EMS-type of symptoms had also been recorded in some cases upon the consumption of 5-hydroxy-L-tryptophan supplements (Klarskov, et al., 1999). One study found that all eight samples of 5-hydroxy-tryptophan products tested positive for at least three contaminants (Klarskov, et al., 1999). Another similar analytical test on six samples of commercially available 5-hydroxytryptophan supplements also revealed adulteration of all products (Klarskov, et al., 2003).

However, extensive test on 5-hydroxy-L-tryptophan supplements and their public use, spanning over decades, hasn't borne the magnitude or type of product contamination or toxicity, namely EMS via GMO L-tryptophan, that had been encountered after the consumption of the Showa Denko products (Murray & Pizzorno, 1998; Das, et al., 2004).

The author of a book on amino acids, Eric R. Braverman, MD, remarked about the 1989 tryptophan-EMS incident that:

“The evidence trail pointed squarely to major contamination in a new processing method developed by one Japanese manufacturer.” (Braverman, 2003) [emphasis added]

Even a study by the US Department of Health and Human Services strongly indicated that tryptophan eosinophilic myalgia is tied to product contamination (Kamb, et al., 1992).

The FDA Tryptophan Recall

-A Matter Of Politics

The indisputable overall evidence attested to an insular, confined tryptophan supplement adulteration (most probably with genetically engineered L tryptophan), as the culprit of the L tryptophan-EMS incident of 1989.


In a political move, the FDA subsequently (in 1990) and irrationally banned basically all tryptophan supplements for over a decade thereafter.

Although, the FDA did allow, dubiously, L-tryptophan to be obtained -at a very steep price- through a doctor's order as the equivalent of a prescription drug (Manders, 1995). Which ignited Dean W. Manders, PhD, to point out that:

“By publicly banning L-Tryptophan from its dietary supplement status and price, while allowing L-Tryptophan to be sold as a high-priced prescription drug, the naked duplicity [=fraud] of the FDA L-Tryptophan policy is revealed.” (Manders, 1995) [explanation added]

So, the FDA called for an universal ban on L tryptophan, rather than banning the particular manufacturer of the product (or rather banning the genetically engineering of L tryptophan) from making or importing any more nutritional supplements until adequate quality standards were implemented and upheld.

Generally, the latter is the basic approach of the public health authorities in cases of confined food poisoning due to contamination.

Food poisoning is very common, and kills several people every day (Schlosser, 2002). In the case of a severe event of food poisoning the regulatory bureaucrats may put a very temporary, transient ban on the availability of the offending food. Upon discernment of the cause, which almost always is contamination due to sloppy food production (Schlosser, 2002), the particular food manufacturer(s) is/are allowed to resume commerce after establishing appropriate food safety and hygiene standards.

Although caused by one single manufacturer, the universal ban of L tryptophan, which lasted for well over a decade, is analogous in "logic" to a general, decade-long ban on all tomatoes because severe produce contamination, which was caused by one single tomato grower, resulted in the death of several people.

When was the last time US health authorities removed all beef or chicken from the marketplace, and left this general ban in place for over a decade, after microbial tainting of the food, which was traced to a single food processing plant (or even several of them), led to the death of three dozen people (about the number of people who died from the 1989 tryptophan-EMS incident)?

The significant circumstantial evidence strongly supports the notion that the absurd FDA tryptophan recall has everything to do with supplement politics.

In 1995, Dean W. Manders, PhD, drew public attention to a 1993 report by the FDA Dietary Supplement Task Force in which it acknowledged that:

"The Task Force considered various issues in its deliberations, including ... what steps are necessary to ensure that the existence of dietary supplements on the market does not act as a disincentive for drug development." (Manders, 1995)

In other words, the FDA was planning on restricting the supplement industry as it is a direct competitor of the medical industry. The federal agency succeeded with its ban on L tryptophan.

The FDA's ban of L tryptophan opened up the marketing avenues of the pharmaceutical industry to promote, largely unobstructed from nonpatentable competing products and substances (e.g., L tryptophan), its sleep-promoting and depression-alleviating drugs such as Prozac® and Paxil® both of which, subsequently, became blockbusters.

Much of the yearly budget of the FDA is coming from the pharmaceutical industry (Angell, 2007). Drug companies routinely entice heads of the FDA with lucrative job offers so that many FDA officials end up working for the drug companies upon leaving the FDA (Lynes, 1990).

Of course, these highly rewarding financial lures and baits cast out by the drug corporations create a strong bias in the actively-serving federal regulators to grant “favors” to the very industry they're supposed to regulate.

The totally nonsensical broad ban of L tryptophan products by the FDA was nothing but a fitting example of how the federal agency was doing the drug cartel a huge favor.

Jonathan W. Emord, Esq., a lawyer who specializes in constitutional and administrative law, specifically FDA law, remarked in an interview:

“[...] the drug industry came to exercise extraordinary influence not only over FDA, but also over Congress, medical school education, medical journal publication and physician prescription practices. No one familiar with it could seriously doubt the degree of control the drug industry has over the Congress of the United States. […]. The drug industry has acquired effective control over a majority of the members of the House and Senate.” (Passwater, Oct. 2008)

Trust obvious facts, not absurd actions by authorities.

Is The L Tryptophan-EMS Problem Remedied?

“[...] who would suspect that our society, those in authority, those we trust with our safety when it comes to purchasing foods and supplements would be so reckless, indeed criminal to encourage and allow a repeat tragedy to happen as did in the 80's with regards to EMS, the first GE caused disease, for the sake of profits.” (Henryk Behr, EMS Sufferer, in 2011)

Cases of tainted L tryptophan EMS have turned up after 1989 and also after the return of tryptophan in 2005 (when the ban on tryptophan got repealed), both in the US and abroad (Reinauer & Plewig, 1991; Grangeia, et al., 2007; Behr, 2011; Medsger, 2012).

The majority of victims are white, middle-aged women (Grangeia, et al., 2007; Okada, et al., 2009; Medsger, 2012). The influence of hormones is a crucial factor for this gender imbalance. Estrogen, which is usually higher in women than men, can increase serotonin and inflammatory tryptophan metabolites (particularly when deficient in vitamin B3), elevating women's risk for EMS (Ellis & Presley, 1973; Murray & Pizzorno, 1998).

In support of Boyens proposition that genetically engineered L-tryptophan led to the disaster of 1989, a consumer of a supplement of tryptophan fell ill with EMS upon ingestion of only 1000mg of the amino acid in late 2010, and, after researching the matter, published a book on the “mystery” of L tryptophan EMS (Behr, 2011).

Behr's investigation corroborated Boyens' and Crist's sensible proposition that it is GMO adulteration that causes presumably the majority, if not all, tryptophan-associated EMS events (Behr, 2011).

Henryk Behr's case illustrates that the root problem of L tryptophan EMS -that is, genetic engineering of the amino acid- still hasn't been corrected after the first decade of the current century, contrary to statements by so-called health experts (Behr, 2011).

Behr claims that all EMS occurrences involve GMO tryptophan (or other tainted supplements). What is certain is that EMS events correlate unmistakably with the introduction of bacterial fermentation as the prominent method to produce L tryptophan in the 1980s (GE tryptophan wasn't available prior to that), and with the advancement in DNA technologies during the same time period (Behr, 2011).

Behr's case suggests that, apparently, the L tryptophan ban by the FDA left the real culprit unscathed, even after the repeal of the ban.

In 1992 the FDA deemed GMO foods safe and exempted them from requiring safety testing which goes against US law (Druker, 2001).

But contrary to the tenets by FDA officials, in 2000 a judge's ruling on genetically engineered foods declared that:

● “The FDA is not regulating GE foods at all.
● The FDA's politically appointed bureaucrats did not follow the advice and warnings of the agency's scientific staff about GE foods but disregarded them.
● There is currently significant disagreement among scientific experts about the safety of GE foods.” (Druker, 2003) [emphasis added]

The judge's indictment that the FDA doesn't regulate GE foods (at all) bears a certain striking similarity to the situation on the policies of dietary supplement regulation, whereas the nutritional supplement industry essentially regulates itself with poor federal oversight (as discussed in my articles on “Regulations”, for instance at Dietary Supplement Regulation -No FDA Approvals For Supplements!).

Notwithstanding that judge's assessments, the FDA keeps misrepresenting the facts about GMO foods. In 2011, the manufacturing of GMO tryptophan remains “a perfectly viable option” to produce a nutritional supplement (Behr, 2011).


"[...] government regulators did not (and do not) regard genetically engineered (GE) foods or GE-produced food supplements as potentially different from conventional ones [...]." (Crist, 2005)

It means that you may not know that you ingest GE supplements since the FDA does not require to disclose this on product labels (Behr was consuming a tryptophan supplement from an US nutritional supplement manufacturer).

All across the planet, GMO foods are poorly regulated by governments (Antoniou, 2012). The weakest regulatory setting (“voluntary industry self-regulation”) exists in the United States, where most such foods originate from (Antoniou, 2012).

As an investigator commented on the utter absurdity of the FDA's L tryptophan ban after the EMS tragedy of 1989:

“[...] even though no conventionally produced L-Tryptophan has been linked with an EMS outbreak, all such supplements have been banned, while all genetically engineered foods have been cleared for sale without testing, even though there are scientifically justified grounds to suspect the bioengineering process itself was the cause of the EMS epidemic.” (Druker, 2001) [emphasis added]

Just as the judge's ruling of 2000 pointed out, even many FDA scientists warned the agency that there is sufficient valid data to seriously question the safety of GMO foods, cautioning that such products cannot be declared safe until tested for safety (Druker, 2001; Antoniou, 2012; Smith, 2012).

Yet the FDA and other health authorities have been denying that GE foods (including GE-produced tryptophan, and GMO-produced nutritional supplements in general) pose a serious health risk, and thus have resisted GMO food labeling laws while dozens of other nations have already implemented such juridical policies.

Some two decades after FDA scientists raised serious concerns about the safety of GE foods, the central body of the orthodox medical establishment, the American Medical Association, is cited twice in the Official Voter Information Guide for the California General Election, Tuesday, November 6, 2012 as proclaiming in June of 2012 that:

"There is no scientific justification for special labeling of bioengineered foods."

Despite that...

Solid research studies have accumulated over the last couple of decades demonstrated that GE foods are quite toxic and harm humans (Antoniou, 2012; Séralini, et al., 2012; Smith, 2012).


“Independent researchers who have published papers containing data that is not supportive of GMOs have been attacked by the industry and pro-GMO groups and individuals.” (Antoniou, 2012)

Why did the FDA disregard the admonitions of its own scientists?

“[...] to “foster” the growth of the GM industry.” (Antoniou, 2012)

The FDA released a policy that GE food don't need safety testing, nor that they require labeling (Antoniou, 2012). The individual responsible at the FDA for overseeing the regulation of GE foods and postulating this ruling was someone who subsequently went on to work for one of the giant GE biotech firms (Monsanto) in a high-level position (Smith, 2012).

The writing on the wall is unmistakable...

The FDA's negligence and denial of the probable involvement of genetically engineering in L tryptophan EMS cases served, and continues to serve, to protect the hugely profitable self-interests of the GMO-biotech industry (Druker, 2001). After all the L-tryptophan disaster of 1989 closely coincides with, and preambled, the lucrative commercialization of GE foods in the US, beginning in the early 1990s (Antoniou, 2012).

The L tryptophan ban by the FDA “to protect the public's health” was a political rather than a humanitarian move.

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Recommended next page(s):

Article Index On
The Politics Of Nutritional Supplements
-How You Get Deceived & Misled

-Revealing Hidden Facts About Vitamins & Supplements


  • Angell M, “Taking back the FDA”, The Boston Globe, February 26, 2007
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  • Behr H, “A Momentary Lapse of Reason: Living With L-tryptophan Induced Ems And The Hidden Dangers Of Genetic Modification Of Our Foods”, 2011
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  • Druker SM, “How The U.S. Food And Drug Administration Approved Genetically Engineered Foods Despite The Deaths One Had Caused And The Warnings Of Its Own Scientists About Their Unique Risks”, Alliance For Bio-Integrity, 2001
  • Druker SM, “How A U.S. District Court Revealed The Unsoundness Of The FDA's Policy On Genetically Engineered Foods”, Alliance For Bio-Integrity, 2003
  • Ellis JM, Presley J, “Vitamin B6 -The Doctor's Report”, Harper & Row, 1973
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  • Hill RH Jr, Caudill SP, Philen RM, Bailey SL, Flanders WD, Driskell WJ, Kamb ML, Needham LL, Sampson EJ, “Contaminants in L-tryptophan associated with eosinophilia myalgia syndrome.”, Arch Environ Contam Toxicol. 1993 Jul;25(1):134-42.
  • Kamb ML, Murphy JJ, Jones JL, Caston JC, Nederlof K, Horney LF, Swygert LA, Falk H, Kilbourne EM, “Eosinophilia-myalgia syndrome in L-tryptophan-exposed patients”, JAMA. 1992 Jan 1;267(1):77-82.
  • Kilbourne EM, Philen RM, Kamb ML, Falk H, “Tryptophan produced by Showa Denko and epidemic eosinophilia-myalgia syndrome.”, J Rheumatol Suppl. 1996 Oct;46:81-8; discussion 89-91.
  • Klarskov K, Johnson KL, Benson LM, Gleich GJ, Naylor S, “Eosinophilia-myalgia syndrome case-associated contaminants in commercially available 5- hydroxytryptophan”, Adv Exp Med Biol. 1999;467:461-8.
  • Klarskov K, Johnson KL, Benson LM, Cragun JD, Gleich GJ, Wrona M, Jiang XR, Dryhurst G, Naylor S, “Structural characterization of a case-implicated contaminant, "Peak X," in commercial preparations of 5-hydroxytryptophan”, J Rheumatol. 2003 Jan;30(1):89-95.
  • Lynes B, “The Healing of Cancer: The Cures, the Cover-ups and the Solution Now!”, 1990
  • Manders DW, “The FDA Ban of L-Tryptophan: Politics, Profits and Prozac”, Social Policy, Vol. 26, No. 2, Winter 1995
  • Mayeno AN, Gleich GJ, “Eosinophilia-myalgia syndrome and tryptophan production: a cautionary tale”, Trends Biotechnol. 1994 Sep;12(9):346-52.
  • Medsger TA Jr, “Eosinophilia-Myalgia Syndrome”, accessed from emedicine.medscape.com, Updated Edition Jan. 2012
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  • Official US Government FDA website, www.fda.gov
  • Okada S, Kamb ML, Pandey JP, Philen RM, Love LA, Miller FW, “Immunogenetic risk and protective factors for the development of L-tryptophan-associated eosinophilia-myalgia syndrome and associated symptoms”, Arthritis Rheum. 2009 Oct 15;61(10):1305-11.
  • Passwater RA, “The Rise Of Tyranny -An Interview With Jonathan W. Emord, Esq.”, Whole Foods Magazine, Oct. 2008
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  • Saito H, Miyamoto T, “Effect of L-tryptophan products on function of human eosinophils: investigation of the causal mechanisms of eosinophilia myalgia syndrome associated with L-tryptophan products”, Int Arch Allergy Immunol. 1996;111 Suppl 1:37-42.
  • Schlosser E, “Fast Food Nation -The Dark Side Of The All-American Meal”, 2002
  • Séralini GE, Clair E, Mesnage R, Gress S, Defarge N, Malatesta M, Hennequin D, de Vendômois JS, “Long term toxicity of a Roundup herbicide and a Roundup-tolerant genetically modified maize”, Food Chem Toxicol. 2012 Sep 11. [Epub ahead of print]
  • Sidransky H, “Tryptophan: Biochemical and Health Implications”, 2001
  • Slutsker L, Hoesly FC, Miller L, Williams LP, Watson JC, Fleming DW, “Eosinophilia-myalgia syndrome associated with exposure to tryptophan from a single manufacturer.”, JAMA. 1990 Jul 11;264(2):213-7.
  • Smith JM, “Genetic Roulette: The Gamble Of Our Lives”, Documentary, 2012
  • Strongwater SL, Woda BA, Yood RA, Rybak ME, Sargent J, DeGirolami U, Smith TW, Varnis C, Allen S, Murphy K, et al., “Eosinophilia-myalgia syndrome associated with L-tryptophan ingestion. Analysis of four patients and implications for differential diagnosis and pathogenesis”, Arch Intern Med. 1990 Oct;150(10):2178-86.
  • Takagi H, Ochoa MS, Zhou L, Helfman T, Murata H, Falanga V, “Enhanced collagen synthesis and transcription by peak E, a contaminant of L-tryptophan preparations associated with the eosinophilia myalgia syndrome epidemic”, J Clin Invest. 1995 Nov;96(5):2120-5.
  • Williamson BL, Tomlinson AJ, Mishra PK, Gleich GJ, Naylor S, “Structural characterization of contaminants found in commercial preparations of melatonin: similarities to case-related compounds from L-tryptophan associated with eosinophilia-myalgia syndrome”, Chem Res Toxicol. 1998 Mar;11(3):234-40.
  • Zangrilli JG, Mayeno AN, Vining V, Varga J, “1,1'-Ethylidenebis[L-tryptophan], an impurity in L-tryptophan associated with eosinophilia-myalgia syndrome, stimulates type I collagen gene expression in human fibroblasts in vitro.”, Biochem Mol Biol Int. 1995 Nov;37(5):925-33.

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