No health effect currently reaches grade A or B under the new rubric. Sexual-function, testosterone, exercise, and metabolic claims are either mixed or too thin to grade, rather than clearly supported. Most positive trials remain small and rely on proprietary extracts.
Each row is a different health effect. A means the support looks strongest, B likely helpful, C mixed or modest, and — not enough human evidence yet.
Papers are individual studies. Research reviews summarize evidence from multiple studies, such as systematic reviews and meta-analyses.
Dose and form from the papers available. Evidence base is limited — apply more skepticism than with better-studied supplements.
Products that pass third-party quality testing.
Grades come from 13 unique research papers indexed from PubMed — including 3 meta-analyses, 2 systematic reviews, and 8 randomized trials. Multiple positive trials use proprietary extracts (Tribestan, furostanol-saponin standardized) where standalone tribulus effect cannot always be isolated. Most health effects were below the threshold to grade. Each supplement is graded by health effect using a certainty × effect matrix applied across PubMed evidence per health effect. Cochrane reviews and high-quality systematic reviews carry the most weight. From abstract-only data, "high certainty" is rare — most A grades come from moderate certainty plus consistent meaningful-positive evidence. See Methodology for full detail.
Read the full methodology → · Download all 13 citations (PDF)