Single-blind testing is a form of blind trial in which the participants do not know which treatment they are receiving, but the researchers do know who gets the supplement and who gets the placebo. It removes the placebo effect from the subjects’ side: they cannot bias their reports by knowing what they took. But it leaves the researchers’ expectations free to influence the results, through subtle cues in how they treat subjects or interpret outcomes. For that reason, single-blind designs are considered weaker than double-blind trials, where neither side knows, and they are mostly used where double-blinding is impractical. In nutrition research, where outcomes are often subjective, the blinding standard can make or break a study’s credibility.