Aspartame ingestion and headaches: a randomized crossover trial.

ABSTRACT

To examine whether ingestion of aspartame is associated with headaches, we conducted a double-blind crossover study using volunteers with self-identified headaches after using aspartame. Of the 32 subjects randomized to receive aspartame (approximately 30 mg/kg/d) and placebo in a two-treatment, four-period crossover design, 18 completed the full protocol, seven completed part of the protocol before withdrawing due to adverse effects, three withdrew for other reasons, two were lost to follow-up, one was withdrawn due to noncompliance, and one withdrew and gave no reason. Each experimental period was 7 days long. Subjects reported headaches on 33% of the days during aspartame treatment, compared with 24% on placebo treatment (p = 0.04). Subjects who were "very sure" prior to the study that aspartame triggered some of their headaches reported larger treatment differences (aspartame = 0.37 headache-days, placebo = 0.18 headache-days; p < 0.001) than subjects who were "somewhat sure" (aspartame = 0.29 headache-days, placebo = 0.22 headache-days; p = 0.51) or "not sure" (aspartame = 0.33 headache-days, placebo = 0.39 headache-days; p = 0.51). There was no significant treatment difference in the length or intensity of headaches or in the occurrence of side effects associated with the headaches. This experiment provides evidence that, among individuals with self-reported headaches after ingestion of aspartame, a subset of this group report more headaches when tested under controlled conditions. It appears that some people are particularly susceptible to headaches caused by aspartame and may want to limit their consumption.