# SupplementAbsorption.com

> How well supplements are absorbed, by form, with food and by timing. Every number is copied exactly as printed in a cited, peer-reviewed study (PMID/DOI), with the species labeled (human, primate, pig, rodent, other animal, in vitro). Educational information about published research; not medical advice.

## Reviewer
- Dr. Colin Reily, PhD (molecular pathology & biochemistry) reviews the science and evidence summaries. He does not give medical advice. All evidence grades are currently labeled "draft, pending reviewer" until he signs off.

## Supplement pages
- [Magnesium](https://supplementabsorption.com/magnesium): glycinate, citrate, oxide, chloride, lactate and more
- [Iron](https://supplementabsorption.com/iron): bisglycinate, ferrous sulfate, fumarate, heme
- [Curcumin](https://supplementabsorption.com/curcumin): piperine, phytosome, micellar, nanoparticle formulas
- [Vitamin D](https://supplementabsorption.com/vitamin-d): D3 vs D2, calcifediol
- [CoQ10](https://supplementabsorption.com/coq10): ubiquinol vs ubiquinone
- [Zinc](https://supplementabsorption.com/zinc)
- [Omega-3 / fish oil](https://supplementabsorption.com/omega-3): triglyceride vs ethyl ester vs phospholipid
- [Vitamin B12](https://supplementabsorption.com/vitamin-b12)
- [Calcium](https://supplementabsorption.com/calcium): citrate vs carbonate
- [Creatine](https://supplementabsorption.com/creatine)
- [CBD & CBDA from hemp](https://supplementabsorption.com/cbd): includes a CBD vs CBDA comparison (#cbd-vs-cbda)
- [Methodology](https://supplementabsorption.com/methodology): evidence grades, species priority, matching rules

## Data sources
- ~918 full-text papers plus PubMed abstracts (PubMed E-utilities, Europe PMC, Unpaywall, OpenAlex). PK values (Cmax, Tmax, AUC with interval, fractional absorption, relative bioavailability) were extracted verbatim with table/page location. Values are never estimated, read off graphs or unit-converted. Paywalled papers we could not obtain are not included.
- Grades (rubric v2, draft — pending reviewer): single-form human PK studies count. Per form "absorption evidence": A = 5+ human studies, 100+ total participants, 2+ randomized/crossover, median CV <=100% (or not evaluable); B = 3+ studies or 2 consistent; C = 1-2 studies; D = animal/in vitro only; median CV >100% lowers one step. Per pair: head-to-heads weigh more; matched single-form (indirect) evidence can reach A (3+ studies per form, clear separation) when it agrees with head-to-heads or none exist; conflict drops one step below the better grade; head-to-head "no difference" is not overridden; comparisons with baseline correction not reported are capped at C. Page/API evidence_grade = best form or pair grade.

## Free API (read-only JSON)
- OpenAPI: https://supplementabsorption.com/api/openapi.json
- List: https://supplementabsorption.com/api/supplements.json
- One supplement: https://supplementabsorption.com/api/supplements/{slug}.json (e.g. magnesium; "cbda" is an alias of "cbd")
- One section: https://supplementabsorption.com/api/supplements/{slug}/sections/{anchor}.json

## Citation policy
- Cite the original study (PMID/DOI shown next to every value), and link the page section, e.g. https://supplementabsorption.com/magnesium#forms.
- Report the species with any value; do not present animal or in vitro data as human evidence.
- Do not present this content as medical advice or as individualized dosing.