see also : “Artificial sweeteners, are they safe?”

Aspartame

Aspartame is the name for an artificial, non-carbohydrate sweetener, aspartyl-phenylalanine-1-methyl ester; i.e., the methyl ester of the dipeptide of the amino acid aspartic acid and the essential amino acid phenylalanine.
This sweetener is marketed under a number of trademark names, such as Equal, NutraSweet, and Canderel, and is an ingredient of approximately 6,000 consumer foods and beverages sold worldwide. It is commonly used in diet soft drinks, and is often provided as a table condiment. It is also used in some brands of chewable vitamin supplements and common in many sugar-free chewing gums. However, aspartame is not always suitable for baking because it often breaks down when heated and loses much of its sweetness. In the European Union, it is also known under the E number (additive code) E951. Aspartame is also one of the sugar substitutes used by diabetics.

History of Aspartame

Aspartame was discovered in 1965 by a chemist working for the American company Searle and an initial marketing authorization (MA) was granted in the United States by the Food and Drug Administration (FDA) in 1974. This MA was suspended a few months later following an appeal against the authorization on the grounds that the toxic and carcinogenic effects on the brain of this compound and its metabolites had not been properly evaluated during the experimental studies. Following a reassessment of the studies on experimental animals and an examination of new data (including a study of carcinogenicity in the rat), the FDA granted this product a new MA in 1981 (FDA, FR 1981) for use in solid food. This authorization was extended to soft drinks in 1983 (FDA, FR 1983) and for its use as a general sweetener in 1996. The safety of aspartame has been assessed and recognized by a number of other national and international organizations including the FAO/WHO Committee of Experts on Food Additives (JECFA) and, at EU level, by the Scientific Committee on Food. It was authorized by Directive 94/35/EC of the European Parliament and of the Council on sweeteners for use in foodstuffs (adopted on 30 June 1994) and its use is permitted in more than 90 countries. In France, aspartame has been permitted since 1988. The Acceptable Daily Intake (ADI) of aspartame for humans was fixed at 40 mg/kg body weight/day by the JECFA (1980).
In 1996, an article by J.W. Olney suggesting a link between an increased incidence of brain tumors in the United States and the marketing of aspartame relaunched the debate on the risks to human health posed by its consumption. The debate has been covered by the media, notably on the Internet where several thousand websites are devoted to the effects of aspartame. These contain allegations claiming that this additive is responsible for a large number of adverse effects (more than fifty), some of which are very serious, such as: multiple sclerosis, lupus erythematosus, Gulf War Syndrome, brain tumors, epileptic seizures, complications of diabetes, etc. At the same time, the health authorities in a number of countries have reacted by informing the public on the studies available or underway and on the data based on scientific evidence.
Following a recap of the physical and chemical properties of aspartame, this report will review, firstly, the available toxicological and epidemiological data on the effects of this additive on the nervous system (cancer and seizures) and secondly, the estimates of the consumption of this sweetener by the general population and by specific populations such as children and diabetic adolescents. For these specific populations, there may be a potential risk arising from heavy consumption, low body mass or finally, a special metabolic susceptibility.”

Aspartame´s properties

Aspartame is an attractive sweetener because it is approximately 200 times sweeter than sugar in typical concentrations, without the high energy value of sugar. While aspartame, like other peptides, has a caloric value of 4 kilo calories (17 kilojoules) per gram, the quantity of aspartame needed to produce a sweet taste is so small that its caloric contribution is negligible, which makes it a popular sweetener for those trying to avoid calories from sugar. The taste of aspartame is not identical to that of sugar: the sweetness of aspartame has a slower onset and longer duration than that of sugar, and some consumers find it unappealing. Blends of aspartame with acesulfame potassium are purported to have a more sugar-like taste, and to be more potent than either sweetener used alone.
Like many other peptides, aspartame may hydrolyze (break down) into its constituent amino acids under conditions of elevated temperature or high pH. This makes aspartame undesirable as a baking sweetener, and prone to degradation in products hosting a high-pH, as required for a long shelf life. The stability of aspartame under heating can be improved to some extent by encasing it in fats or in maltodextrin. The stability when dissolved in water depends markedly on pH. At room temperature, it is most stable at pH 4.3, where its half-life is nearly 300 days. At pH 7, however, its half-life is only a few days. Most soft-drinks have a pH between 3 and 5, where aspartame is reasonably stable. In products that may require a longer shelf life, such as syrups for fountain beverages, aspartame is sometimes blended with a more stable sweetener, such as saccharin. [1]
In products such as powdered beverages, the amine in aspartame can undergo a Maillard reaction with the aldehyde groups present in certain aroma compounds. The ensuing loss of both flavor and sweetness can be prevented by protecting the aldehyde as an acetal.

Daily intake

The Acceptable Daily Intake (ADI) of 40 mg/kg body weight per day set by the committee of experts of the Food and Agriculture Organization (FAO) and the World Health Organization (WHO) is not likely to be exceeded, even by children and diabetics.
A European Commission (EC) report gives a theoretical maximum estimate for adults’ consumption of 21.3 mg/kg body weight per day of aspartame. However, the actual consumption is likely to be lower, even for high consumers of aspartame. The report also gives refined estimates for children which show that they consume 1 to 40% of the Acceptable Daily Intake.
Other reports in Europe use actual food consumption data and actual sweetener levels in foods to estimate that high level intakes for the general population vary between 2.8 and 7.5 mg/kg body weight per day. People with diabetes are high consumers of foods containing aspartame; their highest reported intake varies between 7.8 and 10.1 mg/kg body weight per day.

Metabolization of Aspartame

Upon ingestion, aspartame breaks down into several residual chemicals, including aspartic acid, phenylalanine, methanol, and further breakdown products including formaldehyde and formic acid. There is some controversy surrounding the rate of breakdown into these various products and the effects that they have on those that consume aspartame-sweetened foods (see Aspartame Controversy, below).
The naturally-occurring essential amino acid phenylalanine is a health hazard to those born with phenylketonuria (PKU), a rare inherited disease that prevents the essential amino acid phenylalanine from being properly converted into Tyrosine and eventually being metabolized. Since individuals with PKU must consider aspartame as an additional source of phenylalanine, aspartame-containing foods sold in the United States must state “Phenylketonurics: Contains Phenylalanine” on their product labels.

Concern and controversy around Aspartame

The Scientific Committee for Food (SCF) initially evaluated aspartame (L-aspartyl- L-phenylalanine methyl ester) during 1984 (SCF, 1985) and subsequently during 1988 (SCF, 1989). At its 107th meeting in June 1997, the SCF also examined the issue of an alleged connection between aspartame and increase in incidence of brain tumours in the USA (SCF, 1997).
Aspartame has also been considered by other bodies including the Joint FAO/WHO Expert Committee on Food Additives (JECFA, 1980) the US Food and Drug Administration (FDA, 1984), and the UK Committee on Toxicity (COT, 1992). The toxicity data on aspartame were used by the JECFA, SCF and COT to establish an Acceptable Daily Intake (ADI) of 40 mg/kg body weight/day and an ADI of 50 mg/kg bw/d was established by the FDA. An ADI of 7.5 mg/kg bw/d was also established for a minor cyclic dipeptide derivative of aspartame, a diketopiperazine (DKP), which is formed in some aqueous solutions (JECFA, 1980; SCF, 1985).
The safety issues that have been raised in the past about aspartame have included: (1) the possibility of toxicity from methanol, one of the breakdown products of aspartame; (2) elevations in plasma concentrations of phenylalanine (Phe) and aspartic acid, which could result in increased transport of these amino acids into the brain, altering the brain’s neurochemical composition; (3) the possibility of neuroendocrine changes, particularly increased concentrations in the brain, synaptic ganglia and adrenal medulla of catecholamines derived from Phe and its hydroxylation product, tyrosine; and (4) a postulated link with epilepsy and brain tumours. All these areas have been addressed in the pre-1988 literature and in more recent reviews (Meldrum, 1993; Lajtha et al., 1994; Tschanz et al., 1996).
The safety of aspartame and its metabolic breakdown products (phenylalanine, aspartic acid and methanol) has been assessed in humans generally and in several subgroups, including healthy infants, children, adolescents, adults, obese individuals, diabetics, lactating women, and individuals heterozygous for the genetic disease, phenylketonuria (PKU), who have a compromised ability to metabolize the essential amino acid, Phe.
Since its approval, aspartame has undergone further investigation through clinical and laboratory research, intake studies and post marketing surveillance of anecdotal reports of adverse health effects.
The present review updates the previous SCF opinions in the light of new reports on the consumption of aspartame in relation to the onset of brain tumors and seizures, headaches, allergies, and changes in behavior and cognitive function. Information on the safety of aspartame was available from a variety of sources including scientific papers, conference proceedings, abstracts and magazine articles. This review focuses on papers published in the open scientific literature from 1988 to 2001 and draws on the recent extensive review by the Agence Française de Sécurité Sanitaire des Aliments (AFSSA, 2002), which covered mutagenic, carcinogenic and neurological effects.
On 14 December 2005, a member of the British House of Commons called on the British government to “ban the use and sale of aspartame” due to health concerns relating to this product.

Sources: wikipedia, greenfacts

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