To determine whether there was a connection between the complaint of restless legs and the ingestion of artificial sweeteners in a patient with these symptoms after drinking certain ‘light’ beverages.
Randomised, double-blind, placebo-controlled N-of-1 trial with a cross-over design.
During a period of 48 days, the patient took 4 capsules per day containing either 150 mg of cyclamate, 22.5 mg of saccharine, both sweeteners, or placebo on two successive days. Between each of these 2-day periods there was a 2-day rest period during which no capsules were taken. The hospital pharmacist had prepared the capsules and determined the sequence of the 2-day periods on a random basis. The patient did not know which capsules he was taking. Every day on arising, starting 3 weeks before the trial period, the patient noted the intensity and duration of the symptoms in the late evening and previous night. For this notation he used an 11-point scale, from 0 (= no restless legs) to 10 (= almost total inability to sleep because of restless legs).
A score of 1-3 corresponded to mild symptoms that had no effect on the patient’s sleep; at a score of 4-6 his sleep was disturbed and at a score of 7-10 the patient hardly slept at all. The patient had symptoms more often while using saccharine or the combination of saccharine and cyclamate than when taking the placebo (4 and 4 versus 2 of the 6 nights); moreover, the average score was then statistically significantly higher (5.2 and 5.8 versus 3.3).
There was a connection between the patient’s complaints of restless legs and the use of saccharine, but not the use of cyclamate.
Ned Tijdschr Geneeskd. 2006;150:2796-9