Tryptophan supplements, once marketed as a sleep aid and for bodybuilders, were removed from the UK and US markets in 1989, after they were linked to an outbreak of Eosinophilia-Myalgia Syndrome (EMS) in more than 1500 people. The outbreak also caused 37 deaths.
Since then, a law introduced in England in 1990 has banned the amino acid from being added to foods except in those classified under the EU regulation for PARNUTs (foods for particular nutritional purposes) and for foods consumed under supervision of healthcare professionals.
However the UK's Food Standards Agency (FSA) is planning to add a new exemption to the law so that laevorotatory tryptophan (L-tryptophan) can be marketed in supplement form if the ingredient meets the purity criteria laid out in European Pharmacopeia.
Supplement labels will also be required to advise a maximum daily dose of 220mg.
Changes to the law were triggered by the Institute for Optimum Nutrition (ION), a charity founded by nutritionist Patrick Holford to back nutritional research. In October 2002 ION submitted a report to the FSA calling for the ban on tryptophan supplements to be lifted.
While ION's data were insufficient to change the law, they prompted a formal review by the UK government's Committee on Toxicology of Chemicals in Food, Consumer Products and the Environment(COT).
COT concluded in August last year that L-tryptophan supplements would not present an appreciable risk to health provided that it met certain purity and dosage criteria.
It is difficult to estimate the potential of the ingredient on the supplements market, given its previous history. The global food industry currently only uses around 100-150 tons of the amino acid annually (most is used in animal feed) but the growing weight-loss foods market could drive new growth.
Unilever recently commissioned food research organisation NIZO to manufacture food-grade tryptophan, through an alternative method to the usual fermentation process, for use in a diet beverage.
It is thought that low intake of the amino acid may be responsible for mood swings that make it difficult for some people to stick to a weight-loss regime.
The safety risks highlighted by the EMS outbreak has limited use of single amino acids in European foods but they are widely used in Japan.
Growing interest in Europe in the health and functional properties of peptides increase development of new amino acid-based products.
Alternative manufacturing methods would also open up new opportunities. NIZO said its method, which used the milk protein alpha-lactalbumin as the starting material followed by food-grade enzymes, could remove some of the potential risks of fermentation.
Comments on the changes to the Tryptophan in Food regulations should be sent to Iulia Young at the novel foods, additives and supplements division of FSA by 25 May 2005.
The purity and dosage criteria proposed in the new laws would also apply to the current rules on L-tryptophan use in PARNUTS foods.