2.2. Trial Design and Subjects
ZIEL
SECONDARY
The study was designed as a pilot in a cross-over design to address whether the ingestion of typical amounts of sweeteners may modulate the transcription of chemosensory GPCRs or cytokines and their receptors in isolated neutrophils.The primary and secondary endpoints of our intervention study were the quantification of plasma levels of sweeteners, the quantification of transcript levels of chemosensory GPCRs or cytokines and their receptors in isolated neutrophils, and the statistical analysis of the intervention effects as compared to the water intervention control. These and other analyses not prespecified are considered exploratory. The primary and secondary endpoints of our intervention study did not change during the research or post hoc analyses. The human intervention study was conducted in accordance with the Declaration of Helsinki, and approved by the ethical commission of the faculty of medicine at the Technical University of Munich, Germany (#5798/13, approved on 27 June 2013), and was registered in the WHO partner register DRKS (#DRKS00005083). The study was performed at the ZIEL Institute for Food and Health, Human Study Center of the Else Kröner-Fresenius-Center of Nutritional Medicine (Technical University of Munich, Germany) during July and August 2013. Five female (age range 27–32 yrs, bw 60.3 ± 6.5 kg) and five male (age range 30–47 yrs, bw 80.6 ± 3.5 kg) healthy, non-smoking volunteers were asked to participate in a study consuming either mineral water alone or a combination of saccharin (75.6 mg/L, sodium salt, 0.37 mM), acesulfame-K (52.7 mg/L, potassium salt, 0.27 mM), and cyclamate (227.7 mg/L, sodium salt, 1.13 mM), frequently used in commercially available lemonades, dissolved in mineral water on 2 different occasions. The study was performed after a 7 day run-in period, strictly avoiding non-nutritional sweetener-containing foods (chewing gum, sugar-sweetened beverages, etc.) (After overnight fasting, volunteers were invited to the study center, a venous catheter was inserted, and a baseline blood sample (0 h) was taken; thereafter, either mineral water (10.7 mL/kg bw) as a control, or the mixture of chemically defined sweeteners in mineral water (10.7 mL/kg bw) was given. The volume of the test beverage was calculated to standardize the intake to yield a saccharin concentration of 0.8 mg/kg bw, which is equivalent to commercially available products. Test beverages had to be ingested within 15 min. On test days, blood samples for the isolation of PMNs (see below) or analytics were taken after 0, 4, 8, and 24 h (