Evidence grading methodology

Every protocol page on The Biohacking Bible carries an evidence grade from A to D. The grade reflects the strength of humanevidence as of the page's last review date, not the popularity of the protocol.

The four grades

• Grade A — Multiple high-quality human RCTs converge on the same direction. Effect size has been replicated in independent groups. Risks are well characterised.
• Grade B — Some human RCTs exist, or large prospective cohort data. Results are trending consistent but heterogeneity, dose-response, or population effects remain uncertain.
• Grade C — Mechanism is biologically plausible and well-described. Most human evidence is observational, short-duration, or limited to surrogate endpoints (e.g. acute glucose response rather than long-term metabolic outcomes).
• Grade D — Predominantly animal, in vitro, or anecdotal evidence. Human research is sparse, conflicting, or absent. Treat as informational only.

What the grade does not mean

A grade is not a recommendation. A protocol can be grade A and still be inappropriate for an individual reader because of medications, conditions, or personal circumstances. Always discuss changes that matter to your health with a UK-registered clinician.

Re-grading

Grades are reviewed when the page is reviewed (annually, or sooner if regulatory guidance changes). New systematic reviews or large RCTs can move a protocol up or down a grade.