Not all research is equally reliable. A single mouse study and a 20,000-person clinical trial can both be described as “a study shows,” and that phrasing hides the difference that matters most. This page explains exactly how we sort sources and how we turn that into the grade at the top of every article.
Why we grade at all
Hormone health is a field where confident claims outrun the evidence constantly. Supplements are marketed on rodent data. Protocols spread through podcasts before any trial has tested them. Meanwhile genuinely well-supported findings get lumped in with speculation, so readers end up either believing everything or believing nothing.
Grading is our attempt to fix that. Instead of asking you to trust us, we show you what each conclusion rests on, and we attach a grade that summarizes how much weight the underlying research can actually bear.
How we tier sources
Every source cited on this site is tagged with its study design. Study design is the single best available proxy for how much confidence a result deserves, because it determines what the study can and cannot rule out.
| Tier | Study design | What it can tell you |
|---|---|---|
| 1 | Systematic review, meta-analysis, clinical practice guideline, government or agency source | Synthesizes many studies or reflects expert consensus after formal review. The strongest basis for a general claim. |
| 2 | Randomized controlled trial | Can establish that a treatment caused an effect, because participants were assigned at random. Size and duration still matter. |
| 3 | Cohort study, case-control study | Can show association over time in real populations. Cannot fully separate cause from the traits of people who chose a treatment. |
| 4 | Cross-sectional study, narrative review | A snapshot or a summary. Useful for generating questions, weak for answering them. |
| 5 | Case report, animal study, in vitro study | Shows something is possible in one person, an animal, or a dish. Frequently fails to replicate in humans. |
You will see these tags on every entry in an article’s reference list, so you can check our reasoning rather than take it on faith.
The four grades
Each article’s grade is derived from the mix of sources supporting it.
Strong evidence
Multiple Tier 1 sources agree, meaning several systematic reviews, meta-analyses, or clinical guidelines point the same direction. Further research is unlikely to overturn the conclusion, though it may refine the details.
Moderate evidence
Supported by at least one Tier 1 source, or by two or more randomized controlled trials. The conclusion is reasonable but not settled, and a large future trial could shift it.
Limited evidence
Based mainly on observational studies, small trials, or short follow-up periods. Treat these conclusions as provisional. This grade appears often in hormone research, and that is an honest reflection of the field rather than a failure of our sourcing.
Insufficient evidence
Too little human research exists to draw a conclusion, or the only available research is preclinical. We publish these articles anyway, because “nobody actually knows yet” is useful information that most health sites will not give you. An article supported only by animal or laboratory work can never be graded above Insufficient, regardless of how many such studies exist.
Editorial overrides
An editor can override the computed grade, and sometimes does. Counting study types is a decent rule, but it cannot see that a meta-analysis pooled incompatible studies, that a trial was stopped early, or that a guideline is a decade out of date and contradicted by newer work.
We disclose this because a grading system that hides its own exceptions is not transparent. Overrides move the grade in either direction and are applied by the editor who wrote or updated the article. If you think a grade is wrong, tell us.
What the grade does not mean
- It is not a recommendation. Strong evidence that a treatment works for a population says nothing about whether it is right for you.
- It is not a safety rating. A therapy can be strongly supported for effectiveness and still carry serious risks.
- It is not permanent. Grades change as research accumulates. Every article shows when it was last updated.
- It is not a substitute for a clinician. Nothing on this site can account for your history, medications, or risk factors.
How we choose and cite sources
- We cite primary research wherever possible, not press releases or news coverage of research.
- Every citation links to the source. Where a PubMed record exists, we link to PubMed and show the PMID so you can verify we are describing the study accurately.
- We prefer recent sources, but we do not discard older work that remains the best available evidence on a question.
- We cite studies that contradict our conclusion when they exist, and we say so in the text.
- We do not cite a source we have not read.
Who writes and checks this
Articles are written and fact-checked by the Hormone Hero editorial team against the sources listed on each page. At present, our articles are not reviewed by a licensed clinician. We state this openly on every article rather than leaving you to assume otherwise, and we are working to add clinical review. When an article has been reviewed by a named clinician, that person’s name, credentials, and review date will appear at the top of it, and nowhere else.
We would rather tell you what we are than claim what we are not. Read our editorial policy for how we handle sourcing, corrections, and conflicts of interest.