Study design

The study was performed as monocentric, randomized, placebo-controlled, double-blind cross-over study at the study site BioTeSys GmbH, Esslingen, Germany between October 2014 and August 2015. The study was conducted in accordance with the declaration of Helsinki, complied with principles of Good Clinical Practice (ICH-GCP) and was approved by the responsible Institutional Review Board (Ethics Committee Landesaerztekammer Baden-Wuerttemberg).

After signing the informed consent and prior to trial start, subjects were screened for eligibility. Documentation of demographic data, medical history, nutrition status, vital signs (ECG and blood pressure) and routine blood parameters, including prothrombin time (PT), were recorded. Additionally, homocysteine levels were determined. Subsequently, subjects were instructed about blood pressure reading at home, on the left arm, after at least 10 min of rest, in a sitting position. All subjects received the same blood pressure device (boso medical, PC2) and the 7-day blood pressure diary to measure their blood pressure during the 7 days before the study start at home.

All subjects eligible at visit 1 were randomized to one of the two sequence groups and the study procedures were performed.

At visit 1 adverse events, concomitant medication, endothelial function and routine blood parameters including PT were determined. At the end of the visit, the subjects received study preparations for a period of 4 weeks. At the end of the first supplementation phase (visit 2), endothelial function, postprandial endothelial function, homocysteine, adverse events, concomitant medication, compliance, tolerability, asymmetric dimethyl arginine (ADMA), HbA1c, blood pressure, and routine blood parameters including PT were determined, followed by a wash out period of 8 weeks. For the second supplementation phase, visit 3 and visit 4 were performed following the same procedures performed at visits 1 and 2. Before each visit, subjects measured and documented their blood pressure daily for a period of 7 days. For detailed description see the particular method section.