Evidence
Grades per claim, with the reasoning attached
An ingredient can have strong evidence for one outcome and thin evidence for another, so we grade each ingredient–outcome pair separately. Every grade carries a rationale, sources, limitations and a review date.
Scale
How the grades are defined
- S
- Very strong, consistent human evidence — typically multiple high-quality randomized trials and/or high-quality systematic reviews.
- A
- Strong human evidence with generally consistent results.
- B
- Moderate human evidence; promising, with meaningful limitations or inconsistency.
- C
- Limited or preliminary human evidence.
- D
- Primarily mechanistic, animal, observational or otherwise weak evidence.
- F
- Adequate evidence suggests the marketed claim is unsupported, ineffective or misleading.
Ingredient claims
Ingredient and outcome pairs
Same ingredient, different outcome, different grade. That is the point.
| Ingredient | Outcome | Grade | Rationale & limitations | Reviewed |
|---|---|---|---|---|
| Creatine monohydrate | Strength and power performance | S | Large body of randomized trials and multiple systematic reviews report consistent gains in high-intensity performance when combined with resistance training. Limitations: Effect sizes vary with training status and baseline muscle creatine. | 2026-06-01 |
| Creatine monohydrate | Cognitive performance | C | Some trials suggest benefit under sleep deprivation or in vegetarians, but results across healthy rested adults are inconsistent. Limitations: Small samples, heterogeneous cognitive endpoints, short durations. | 2026-06-01 |
| Magnesium | Subjective sleep quality | C | Modest improvements reported in small trials, often in older adults or people with low intake. Limitations: Few well-powered trials; forms and doses differ widely. | 2026-05-18 |
| EPA/DHA | Triglyceride reduction | A | Dose-dependent triglyceride lowering is reproducible across trials, with larger effects at higher intakes. Limitations: Effects on cardiovascular events depend on dose, formulation and population. | 2026-05-22 |
| Ashwagandha | Perceived stress | B | Several randomized trials report reductions in stress scales over 8–12 weeks. Limitations: Many trials are small, industry-funded, and use different extracts and scales. | 2026-04-30 |
| Psyllium husk | LDL cholesterol reduction | A | Consistent modest LDL reduction across controlled feeding and supplement trials. Limitations: Requires sustained daily intake; adherence drives the effect. | 2026-05-02 |
| Berberine | Fasting glucose and HbA1c | B | Meta-analyses of mostly small trials report glycemic improvement, several conducted in one region with variable methodology. Limitations: Known drug interactions, GI tolerability, and quality concerns in the trial literature. | 2026-04-12 |
| Collagen peptides | Reversing skin aging | D | Marketed claims outrun the evidence; available trials are short, small and frequently manufacturer-funded. Limitations: Subjective endpoints and high risk of bias. | 2026-03-28 |
Grades are editorial and are maintained independently of any commercial relationship. Commission never influences a grade.
Study library
The research behind the grades
Each record keeps population, dose, duration, comparator, result, limitations and funding, so you can judge the study rather than a summary of it.
Placeholder record — creatine supplementation and resistance-training outcomes
Pending editorial verification · Pending, 2026 · Systematic review (placeholder)
- Population
- Healthy trained adults
- Sample size
- Pending
- Dose & duration
- 3–5 g daily, 6–12 weeks
- Funding
- Pending disclosure
Development placeholder demonstrating the study record layout. No real study is described here, and no citation is asserted.
Limitations: Placeholder record; not a source for any claim.
Identifier: Unverified — awaiting editor
Placeholder record — omega-3 dose response and serum triglycerides
Pending editorial verification · Pending, 2026 · Meta-analysis (placeholder)
- Population
- Adults with elevated triglycerides
- Sample size
- Pending
- Dose & duration
- 1–4 g EPA+DHA daily, 8–24 weeks
- Funding
- Pending disclosure
Development placeholder demonstrating how dose, comparator and outcome fields render. No real study is described here.
Limitations: Placeholder record; not a source for any claim.
Identifier: Unverified — awaiting editor
Study records are placeholders during development and are labelled as such. We never fabricate citations; unresolved identifiers stay blank until an editor verifies them.
Health topics
Start from a topic instead of a product
Sleep
Duration, efficiency and timing, and what actually moves them.
Key biomarkers: HRV, Resting heart rate, Ferritin
Cardiovascular health
Lipids, blood pressure and inflammation, and how they respond to change.
Key biomarkers: ApoB, LDL-C, Lp(a), hs-CRP
Metabolic health
Glucose regulation, insulin sensitivity and body composition.
Key biomarkers: HbA1c, Fasting insulin, Triglycerides
Hormone health
What is measurable, what varies by time of day, and what needs a clinician.
Key biomarkers: Total testosterone, SHBG, TSH, Estradiol
Cognition
What is measurable at home versus what needs formal testing.
Key biomarkers: Homocysteine, Vitamin B12, Vitamin D, 25-OH
Gut health
Fiber, tolerance and the limits of current consumer testing.
Key biomarkers: hs-CRP, Ferritin