One nice feature of Natural Standard which makes it unique is that it employs a grading system to show expert opinions. For example, an article designates with A means it has a strong scientific evident. It has a statistically significant evidence of benefit from properly randomized trials (RCT), or evidence from one properly conducted RCT and one properly conducted meta-analysis, or evidence from multiple RCTs with a clear majority of the properly conducted trials showing statistically significant evidence of benefit and with supporting evidence in basic science, animal studies, or theory. B means good scientific evidence. This grade applies to situations in which a well designed randomized controlled trial reports negative results but stands in contrast to the positive efficacy results of multiple other less well designed trials or a well designed meta-analysis, while awaiting confirmatory evidence from an additional well designed randomized controlled trial. C means unclear or conflicting scientific evidence. D means fair negative scientific evidence. It also has a level called Lack of Evidence, which means the team of experts cannot evaluate the efficacy of the experiment due to lack of adequate available human data.
In short, Natural Standard is a good and reliable source of information on alternative and holistic medicine.