The European Food Safety Authority's Panel on Food Additives and Nutrient Sources Added to Food has some interesting things to say about aspartame. Although past animal studies found evidence of chronic toxicity, human studies did not produce the same data. In fact, peak toxicity levels were below the current clinical guidelines.
In other words, the latest evidence indicates that consuming normal aspartame is not a danger to health.*
How Did the Data Support This Assertion?
Initially, animal studies established both chronic and developmental toxicities in the bloodstream after aspartame consumption (and its transformation to phenylalanine, aspartic acid, and methanol during digestion). The abstract of the panel's findings states "From chronic toxicity studies in animals, a NOAEL of 4000 mg/kg bw/day was identified. The possibility of developmental toxicity occurring at lower doses than 4000 mg/kg in animals could not be excluded."
However, the data also indicated that phenylalanine was the cause of this toxicity in animals, leaving open the question of how humans may metabolize aspartame, and whether the blood concentrations would be different. And so, "The Panel concluded that human data on developmental toxicity were more appropriate for the risk assessment." That said, when it came down to reviewing the data, the panel performed a comprehensive review of scientific studies of both humans and animals.
The panel drew from a pretty full data pool. According to the data summary, "The Panel based its evaluation on original study reports and information submitted following public calls for data, previous evaluations, and additional literature that has become available until the end of the public consultation on the draft Scientific Opinion on the re-evaluation of aspartame (E 951) as a food additive (15th February 2013). The Panel also evaluated literature published after the end of the public consultation, until 15th November 2013 (EFSA ANS Panel, 2013)."
When it came down to the data itself, the panel drew conclusions based on...
- Data from people with phenylketonuria (PKU)
- The fact that many models use very conservative assumptions, overestimating peak plasma concentrations
- The way that models allocate 2/3 of the clinical guideline levels of phenylalaline in plasma to phenylalanine from aspartame that a subject ingests, so that the models can account for simultaneous ingestion of phenylalanine from other parts of the diet
- Kinetic data from studies that involved humans taking in aspartame orally and repeatedly
- The fact that bolus intakes of aspartame at the maximum permitted levels by children will not exceed 30 mg aspartame/kg bw
What Did the Panel Conclude?
The bottom line is that "the available data do not indicate a genotoxic concern for aspartame." The researchers expand on that point, asserting, "Overall, the Panel concluded from the present assessment of aspartame that there were no safety concerns at the current ADI of 40 mg/kg bw/day. Therefore, there was no reason to revise the ADI for aspartame."
But could people reasonably and accidentally consume too much aspartame and endanger their health? Well, the panel is skeptical, maintaining, "Based on these considerations and evaluations, the Panel concluded that under realistic conditions of aspartame intake, phenylalanine plasma levels would not exceed 240 µM in normal or PKU heterozygous individuals. The Panel noted that this was well below the concentrations at which adverse effects in the fetus are reported and is also below the current clinical guideline (360 µM) for prevention of effects in the fetuses of pregnant PKU patients."
What About People with Phenylketonuria (PKU)?
People with PKU should still avoid aspartame. The panel's evaluation of phenylalanine plasma levels based on a serving of aspartame did not apply to people with PKU, and the ADI that the panel supported was also not applicable to people with PKU. People with PKU should adhere to the guidelines established by their doctors or registered dietitians, strictly limiting phenylalanine and avoiding any products with aspartame.
Where is This Study?
You can access the European Food Safety Authority's Panel on Food Additives and Nutrient Sources Added to Food's report at the website for the EFSA journal. It was published on December 10, 2013.
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* Except for people with PKU, of course.