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Chapter 16 — Further Reading
The two free resources you should actually use
NIH Office of Dietary Supplements — ods.od.nih.gov
Fact sheets for essentially every supplement in this chapter, in consumer and professional versions, free and regularly updated. Each includes what the evidence shows, upper limits, and drug interactions. They are notably willing to say "the evidence is insufficient," which almost nothing else in this space does.
Start with the creatine, biotin, and St John's Wort sheets.
NIH LiverTox — livertox.nih.gov
A free, authoritative database of drug- and supplement-induced liver injury. Look up green tea extract, garcinia, kava, and ashwagandha. ⚠️ This is where post-market surveillance actually happens, and it is the single most sobering half-hour available on this topic.
On regulation
DSHEA 1994 itself, or a good legal summary — search "Dietary Supplement Health and Education Act summary." Understanding the burden-of-proof reversal (§16.1) makes the rest of the aisle legible.
FDA supplement pages (fda.gov) — including guidance on structure/function claims, cGMP
requirements, and the tainted products database. ⚠️ Search the database for any category you buy
from. It takes two minutes and is more persuasive than any argument here.
On other jurisdictions: the EU register of permitted health claims (considerably more restrictive than the US), Australia's TGA listed medicines framework, and Health Canada's Natural Health Products regime. Comparing them is a good exercise in what each system trades away.
On creatine
The ISSN Position Stand on creatine supplementation — Journal of the International Society of Sports Nutrition, open access. This is the authoritative summary: what's established, at what dose, with what safety data, and — usefully — what the authors decline to claim.
For the safety question: search for long-term studies on creatine and renal function in healthy individuals, and for reviews addressing the creatinine artefact specifically. ⚠️ The distinction between raised creatinine and kidney injury is the practical point.
On the emerging cognitive literature: search "creatine cognition sleep deprivation" and "creatine supplementation vegetarians." Genuinely interesting, considerably less settled than the strength data — read it as promising rather than established, which is how §16.3's verdict treats it.
On caffeine
The ISSN position stand on caffeine and exercise performance, open access. Dose, timing, individual variation, and the genetic component. Then note the contrast with Chapter 5 §5.8, where caffeine's metabolism-boosting claim received a much cooler verdict — same compound, different claim, different evidence.
On adulteration and contamination
Pieter Cohen's research on supplement adulteration — search his published work on undeclared pharmaceutical ingredients, unapproved stimulants, and products remaining on sale after FDA warnings. He is the most rigorous voice in this area and his findings are consistently uncomfortable.
On testing programmes: NSF Certified for Sport (nsfsport.com), Informed Sport
(sport.wetestyoutrust.com), USP Verified (usp.org). ⚠️ If you are subject to drug testing,
read the strict liability provisions of your sport's anti-doping code first, then use only certified
products.
On biotin interference — the case study's evidence
FDA safety communications on biotin and laboratory test interference (2017, updated 2019) —
fda.gov. Short. ⚠️ If you take any "hair, skin and nails" product, read this before your next blood
test.
On the clinical literature: search "biotin interference immunoassay troponin" and "biotin interference thyroid function tests." The distinction between sandwich assays (falsely low) and competitive assays (falsely high) is the part clinicians most need and least often have.
And a question worth asking locally: is your laboratory's troponin assay biotin-sensitive? Most patients cannot find out, which is itself the finding.
On interactions
Your pharmacist, genuinely — in most systems a medication and supplement review is free, takes ten minutes, and is the single most useful thing on this page.
On St John's Wort specifically: search for reviews on "St John's Wort CYP3A4 induction drug interactions", and for documented cases of contraceptive failure and transplant rejection. ⚠️ Then consider that it sits on a pharmacy shelf with no point-of-sale warning.
Reference tools: the Natural Medicines Comprehensive Database (subscription, used clinically) and Drugs.com's interaction checker (free, less complete). Neither replaces a pharmacist.
On the evidence for specific supplements
Examine.com — an independent, subscription-based database summarizing the human evidence for individual supplements, graded and referenced. It is the most useful single resource for looking up something not covered in this book, and it is generally careful about distinguishing mechanism from outcome.
Cochrane (cochranelibrary.com) — plain-language summaries free. Search any supplement plus your
outcome of interest. Note how frequently the conclusion is "low certainty."
A note on what to be careful with
This chapter has an asymmetry worth naming explicitly, because it's the failure mode a sceptical reader is most likely to hit.
The correct conclusion from Part III is not "supplements don't work." Six ✅ verdicts and four 🟢 sit in these four chapters, and some of them matter enormously — folic acid prevents irreversible birth defects; B12 prevents irreversible neurological damage; ORS saves lives at scale; iron reverses genuine disability; creatine is the best-evidenced ergogenic aid there is, for eighty dollars a year.
A reader who finishes Part III and stops taking B12 while eating a vegan diet has made a much worse error than the one they were avoiding.
The test that separates the two groups, and it works on anything: does the source specify who is deficient, why, how it would be measured, and at what dose? Folic acid preconception answers all four. "Supports immune health" answers none.
That difference is the whole of Part III, and it is more useful than any list of products — because the products turn over and the question doesn't.