How to Verify a Supplement Before You Take It

A bottle on a shelf tells you three things: what the seller says is inside, how much of it they say is there, and what they hope you will believe it does. Nobody checks any of the three before you buy, because the U.S. Food and Drug Administration does not approve dietary supplements before they are sold. That is also the honest reason a list of “safe brands” is the wrong tool: it goes stale the day a formula, a supplier or an owner changes, and a non-profit has no business endorsing one company over another anyway. What does not go stale is knowing how to check any bottle in a few minutes. This page teaches those checks: what the third-party seals actually verify and what they cannot, how to read a Supplement Facts panel without being fooled by it, the two-minute look-up in the FDA’s own records, the handful of drug interactions that cause real harm, and the one habit that does more than any seal.

Table of Contents

  1. Why the Label Alone Cannot Be Trusted
  2. The Third-Party Seals: What Each One Checks, and What It Does Not
  3. “Third-Party Tested” Versus a Certification You Can Look Up
  4. How to Read a Supplement Facts Panel
  5. The Two-Minute FDA Check
  6. The Drug Interactions That Matter Most
  7. Who Should Be Extra Careful
  8. The One Habit That Does More Than Any Seal
  9. What to Do When Something Goes Wrong
  10. The Honest Bottom Line
  11. Research Papers
  12. Connections
  13. Featured Videos

1. Why the Label Alone Cannot Be Trusted

A supplement label is written by the seller and, for most products, is never checked by anyone else. When independent laboratories do check, the gap is large and it runs in both directions. In 2021 researchers bought 30 “immune support” products from Amazon and analysed them by mass spectrometry: 17 of the 30 were mislabelled — 13 were missing ingredients printed on their own labels, 9 contained substances that were not on the label at all, and not one of the 30 carried a third-party certification seal (Crawford 2022). Over-the-counter vitamin D pills tested in 2013 held anywhere from 9% to 146% of the dose on the label (LeBlanc 2013). Thirty-one melatonin products ranged from 83% below to 478% above their label claim, varied by as much as 465% between lots of the same product, and eight of them contained serotonin, a related compound that has no business being there (Erland 2017). Of 32 fish-oil supplements on the New Zealand market, only 3 contained the EPA and DHA they claimed, and 83% were oxidised beyond the recommended peroxide limit (Albert 2015). Those are the honest failures — sloppy manufacturing, unstable ingredients, no testing. The dishonest ones, where a prescription drug is added on purpose to a “natural” product, are the subject of the first page in this section, Hidden Prescription Drugs in “Natural” Supplements. The point is not that every bottle is wrong; most are roughly right. The point is that you cannot tell which from the label, so you need a check that does not depend on the label.

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2. The Third-Party Seals: What Each One Checks, and What It Does Not

A certification seal is a statement about the bottle, not about the idea behind it. Every reputable programme answers the same narrow question — is this product what its label says it is? — and none of them answers the question people assume a seal answers, which is whether the ingredient does anything. The programmes below are organisations, not brands; each description is taken from the programme’s own published rules, linked in the Regulatory Records at the end of this page.

USP Verified Mark (United States Pharmacopeia)

USP is the non-profit that writes the quality standards for American medicines. When its Verified Mark is on a label, USP states that the product has been independently reviewed and tested to confirm four things: it contains the ingredients listed on the label in the declared strength and amounts; it does not contain harmful levels of specified contaminants such as heavy metals and pesticides; it complies with FDA Good Manufacturing Practices; and it will break down and dissolve within a specified time so the ingredients can actually be absorbed. That last point is worth noticing — a tablet that passes through you intact is a tablet that was verified for nothing. To carry the mark, the manufacturer’s facility is audited against USP General Chapter <2750> and the FDA’s manufacturing rule (21 CFR Part 111), its quality-control paperwork is reviewed and samples are tested in a laboratory. In early 2026 USP’s consumer site listed more than 160 verified supplement formulas. That is a small fraction of the market, which is precisely why the mark means something. The site has a product finder, so you can check whether the bottle in your hand is in it.

NSF (NSF/ANSI 173) and NSF Certified for Sport

NSF certifies supplements against NSF/ANSI 173, the American National Standard for dietary supplement ingredients. Its programme has three parts: a label-claim review (what is on the label is in the bottle), a toxicology review of the ingredients that were added on purpose, and a contaminant review (no undeclared ingredients, no unacceptable levels of contaminants). NSF tests in its own accredited laboratories rather than accepting a manufacturer’s data, conducts annual audits, and periodically retests each certified product. NSF Certified for Sport adds a screen for 280 substances banned by most major athletic organisations, plus undeclared stimulants, narcotics, steroids, diuretics, beta-2 agonists and masking agents; it is the programme the NFL, MLB, PGA and LPGA recognise, and the reason a non-athlete might care is that the banned-substance screen is also a screen for the drugs most often hidden in muscle and weight-loss products. Certified products are searchable on NSF’s sites.

Informed Sport and Informed Choice (LGC)

These two marks come from the same laboratory group and are easy to confuse, and the difference is exactly the kind of thing a reader should learn to spot. Informed Sport tests every batch of a certified product for more than 285 substances banned in sport before it is released for sale, and follows up with blind purchases from shops; every tested batch is listed, and you search the database by batch number. Informed Choice is a retail-monitoring programme: at least twelve lots a year are bought blind from shops or websites and tested at random, and LGC itself states that, unlike Informed Sport, it is not guaranteed that every batch has been tested. Both are honest programmes. One tells you about the batch in your hand; the other tells you about the brand’s track record.

BSCG Certified Drug Free

The Banned Substances Control Group tests every lot of a participating product against more than 450 drugs — over 400 on the World Anti-Doping Agency list plus more than 50 illicit, prescription or over-the-counter drugs that are not banned in sport but do turn up in supplements — alongside label-claim verification, contaminant testing and a manufacturing audit. Its database keeps four years of tested lots, and BSCG’s own sentence is the rule to remember for every programme on this page: “If a lot is not listed it has not been tested.”

ConsumerLab.com

ConsumerLab is not a seal you will often see; it is an independent testing company. It buys products at retail — it does not accept samples from manufacturers — sends them, with identities blinded, to outside accredited laboratories, and publishes the results as product reviews that are paid for by reader memberships rather than by advertising. It also runs a separate Quality Certification Program: a manufacturer pays to have a product tested, and if it passes may license the CL seal, with a fresh open-market sample retested every twelve months. The reviews are the independent part; the seal is voluntary and paid for, though the testing behind it is the same. For a reader trying to judge a specific bottle, the value is the review: it tells you which of a dozen brands of the same ingredient passed and which did not, which no seal does.

What no seal checks

A seal verifies what is in the bottle. It does not verify that you should take it.

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3. “Third-Party Tested” Versus a Certification You Can Look Up

The phrase “third-party tested” has no legal definition. The FDA does not define it, nobody audits its use, and it can truthfully describe one sample, tested once, for one thing, at a laboratory the company chose and paid. “Lab verified”, “clinically tested”, “pharmaceutical grade” and “GMP certified” (which every supplement manufacturer is legally required to be) are the same kind of words: they cost nothing to print and prove nothing. A named certification is different in one concrete way — it leaves a trail you can follow. Three steps:

  1. Name the certifier. A real seal names the organisation (USP, NSF, Informed Sport, BSCG). A shield-shaped graphic that says “Tested” or “Quality Assured” and names nobody is decoration.
  2. Find the product in the certifier’s own database, not on the seller’s website. Every programme above publishes a searchable list. If the product is not in the list, the seal on the box means nothing, whatever it looks like — printed seals are copied, and the database is the only defence against that.
  3. Match the lot number. Find the lot or batch number on your bottle (usually near the expiry date). For the sport programmes and BSCG, the database lists tested lots; if yours is not there, it was not tested. For USP and NSF, which certify the product line and retest periodically, confirming the product is listed is the check.

Some brands post a certificate of analysis instead of, or as well as, a seal. A useful certificate names an independent laboratory, carries a lot number that matches your bottle, and lists the tests actually run — identity, potency, heavy metals, microbes. A certificate from the company’s own laboratory, with no lot number, is a brochure. And keep the Amazon study in mind: none of the 30 immune products carried a certification seal, and most had inaccurate labels (Crawford 2022). The absence of a seal is the norm, which is what makes its presence, once you have looked it up, real information.

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4. How to Read a Supplement Facts Panel

Serving size is chosen by the seller

Every amount on the panel is per serving, and the manufacturer sets the serving size within the FDA’s labelling rule (21 CFR 101.36, which sends you to 101.12(b): the serving is the maximum amount the label recommends per occasion). So “Vitamin C 1,000 mg” may be per capsule or per three, and “Servings per container: 30” on a 90-capsule bottle means three a day. Two habits fix this: read the serving size before any other number, and when comparing two products compare the per-day amount and the per-day price, never the per-serving figures the front label prefers.

%DV is a target, not a ceiling

“% Daily Value” measures each nutrient against the FDA’s Daily Value — an amount to aim for, roughly the recommended intake of a healthy adult. It says nothing about the most you can safely take. That number is the Tolerable Upper Intake Level (UL), set by the National Academies and listed in every NIH Office of Dietary Supplements fact sheet, and the label never mentions it. Putting the two side by side for the nutrients most often overdosed, using the FDA’s Daily Values and the ODS adult ULs:

Several thousand percent of the Daily Value is not automatically dangerous — vitamin B12 has no UL because no toxic dose has been found — but for anything on the list above it is a reason to compare against the UL. And the UL is for the whole day from everything you take: a multivitamin plus a B-complex plus an “energy” shot plus fortified cereal add up, which is how most vitamin overdoses on this site’s Vitamin and Mineral Overdose page actually happen.

“Proprietary blend” means the doses are hidden on purpose

The FDA’s labelling rule, 21 CFR 101.36(c), lets a manufacturer group ingredients into a “Proprietary Blend” (or any fanciful name), list the ingredients inside it in descending order by weight, and print only the total weight of the blend — not the amount of each ingredient. So “Thermogenic Matrix 1,200 mg: green tea extract, caffeine, yohimbe bark, bitter orange” is legal, and tells you the caffeine could be 5 mg or 400 mg. You are only guaranteed that the first-listed ingredient weighs the most. The practical rule: treat a blend as an unknown dose of every ingredient in it. For a herb with no upper limit that may not matter; for a stimulant, a sedative, or anything on the UL list above, it is a reason to choose a product that prints the numbers. Companies that are proud of their doses print them.

Forms and units that change what you are getting

“Standardized to 24%” is about consistency, not identity

For a herb, “standardized to 24% flavone glycosides” means the extract has been adjusted so that one marker compound sits at a fixed concentration in every batch. That buys consistency of the marker. It does not prove the marker is the part that works, that the rest of the extract is right, or even that the plant is the one on the label: a 2019 review of DNA-based authentication found adulteration — substitution, contamination or filler species — in 27% of 5,957 commercial herbal products tested worldwide (Ichim 2019). Identity is a separate question from standardisation, and a certifier’s identity test is the only thing on a label that answers it. The site’s Contamination and Substitution page covers what turns up when the plant is not what it says.

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5. The Two-Minute FDA Check

The FDA cannot test the market, but it does publish what it has caught, and the records are free and searchable. With the bottle in front of you:

  1. Search the Health Fraud Product Database. This is the FDA’s list of products that have been the subject of a health-fraud notification — most of them because laboratory testing found a hidden drug. Search by product name, by company, and then by the main ingredient, because the same tainted formula is often sold under several names. Each entry links to the notification that names the drug found. The same information is also grouped by category on the FDA’s Medication Health Fraud Notifications pages (sexual enhancement and energy, weight loss, and others), which is the place to browse if you want to see what a category looks like before you buy anything in it.
  2. Search Recalls, Market Withdrawals and Safety Alerts. Set the product-type filter to “Dietary Supplements” and search the brand. Recalls for hidden drugs, contamination and mislabelling all appear here, with the company’s own recall notice attached.
  3. Check MedWatch safety alerts. MedWatch is the FDA’s safety-information and reporting programme; its alerts cover supplements as well as drugs and devices, and it is also where you will report a problem if one happens (section 9).
  4. Then check the certifier’s database with your lot number, as in section 3. The FDA records tell you whether a product has been caught; the certifier’s records tell you whether it has been checked. Those are different questions and you want both answers.

A clean search is not a clean bill. Between 2007 and 2016 the FDA warned about 776 products containing unapproved drugs (Tucker 2018), in a market of tens of thousands of products, and when researchers re-bought supplements months to years after an FDA recall, about two-thirds still contained the banned drug (Cohen 2014) — a recall notice tells you a product was caught, not that it was fixed. The database catches known offenders. The pattern catches the rest: a sexual-enhancement, weight-loss or muscle product, sold as “natural”, that promises a drug-sized effect. That pattern, and why it is reliable, is the subject of Hidden Prescription Drugs.

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6. The Drug Interactions That Matter Most

Most supplement–drug interactions are small and theoretical. A handful are large, well documented and predictable, and they cluster around a few drugs with narrow safety margins. If you or someone you look after takes any of the drugs named below, these are the interactions worth memorising.

Warfarin: vitamin K, vitamin E, fish oil, ginkgo, garlic

Warfarin works by blocking the recycling of vitamin K, which the liver needs to finish making four clotting factors. Anything that changes the vitamin K supply, or that affects clotting from another direction, moves the INR — the blood test that measures how thin the blood is (see PT/INR Test). Vitamin K itself, in a multivitamin, a “bone formula” or a green-juice powder, pushes the INR down; the answer is consistency rather than avoidance — pick an intake and keep it, and tell the clinic when it changes (see Vitamin K). Vitamin E in high doses works against vitamin K: 1,000 IU a day for 12 weeks raised PIVKA-II, the blood marker of under-carboxylated prothrombin and therefore of poorer vitamin K status, several-fold in two trials of people who were not on anticoagulants at all (Booth 2004; see Vitamin E). Fish oil: a 67-year-old woman whose INR had been stable for five months saw it rise from 2.8 to 4.3 within a month of doubling her fish oil from 1 g to 2 g a day, with nothing else changed (Buckley 2004). Ginkgo and garlic both appear in published case reports of interaction with warfarin, and ginkgo also with aspirin and ibuprofen (Izzo & Ernst 2009; see Ginkgo Biloba and Garlic). A systematic overview of warfarin interactions found 181 published reports covering 120 drugs and foods; 72% described a stronger warfarin effect, and most were single case reports of poor quality (Holbrook 2005) — which is the fair summary of the whole subject. The risk is real, the size of it in any one person is unknowable in advance, and the INR is the test that settles it. The rule: nothing new, and nothing stopped, without telling the anticoagulation clinic, and an INR check within one to two weeks of any change.

Nitrates and any “natural” product for erectile function

Anyone taking a nitrate — nitroglycerin tablets or spray, isosorbide mononitrate or dinitrate — must treat every “natural” product sold for erectile function as if it contained sildenafil, because it may. Sexual-enhancement supplements with undeclared sildenafil or tadalafil are the products the FDA flags most often. A PDE5 inhibitor and a nitrate together can drop blood pressure precipitously, and the 1999 American College of Cardiology / American Heart Association consensus lists concurrent nitrate use as the one setting in which sildenafil is “clearly contraindicated” (Cheitlin 1999). Here the drug is hidden, so knowing the rule is not enough to avoid it; only avoiding the category is. The mechanism and the named products are on Hidden Prescription Drugs.

Antidepressants: St John’s wort and 5-HTP

St John’s wort induces the liver enzymes CYP3A4, CYP2C9 and CYP1A2 and the transporter P-glycoprotein, which speeds the clearance of many drugs and lowers their blood levels — warfarin, cyclosporine, HIV protease inhibitors, digoxin, theophylline and oral contraceptives among them — and it also acts on serotonin itself, so combined with an SSRI or a migraine triptan it adds serotonin from a second direction (Henderson 2002). The degree of enzyme induction is unpredictable because the herb’s active content varies from product to product, which is section 1 again. 5-HTP is the immediate precursor of serotonin; the safety concern reviewed for it is serotonin syndrome (Turner 2006) — agitation, sweating, tremor, a racing heart, a rising temperature — and with a monoamine-oxidase inhibitor the combination is the most dangerous of all. Neither belongs alongside an antidepressant without the prescriber knowing, and St John’s wort should never be started or stopped silently by anyone on a drug with a narrow margin, because the drug’s level moves both ways.

Chemotherapy and antioxidants: the evidence is genuinely split

Antioxidants (vitamins A, C and E, carotenoids, coenzyme Q10) protect cells from oxidative damage; several chemotherapy drugs work partly by causing it; the worry is that the supplement shields the tumour along with the patient. A 2008 systematic review of 33 randomised trials with 2,446 patients found that antioxidants mostly reduced side-effects and that one trial (vitamin A) increased them — but those trials measured toxicity, not whether the cancer came back (Block 2008). In 2020 a prospective study nested in a breast-cancer chemotherapy trial (SWOG S0221, 1,134 patients) found that antioxidant use both before and during treatment was associated with a higher hazard of recurrence (adjusted hazard ratio 1.41, 95% CI 0.98–2.04 — short of statistical significance) and of death (1.40); vitamin B12 taken before and during chemotherapy was associated with significantly worse disease-free survival (1.83) and overall survival (2.04), iron during chemotherapy with recurrence (1.79), and a multivitamin with nothing at all (Ambrosone 2020). That is observational and not proof. But the direction matches the mechanism, and the study’s own conclusion — caution with anything beyond a multivitamin during chemotherapy — is the sensible one. Bring every product to the oncology team before the first cycle, and expect the answer to be “not during treatment” for the antioxidants.

Anti-rejection drugs and St John’s wort

Two heart-transplant patients developed acute rejection after starting St John’s wort; it had driven their cyclosporine levels down (Ruschitzka 2000). Tacrolimus is affected the same way (Izzo & Ernst 2009). For anyone on an anti-rejection drug, St John’s wort is not a “be careful”. It is a never.

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7. Who Should Be Extra Careful

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8. The One Habit That Does More Than Any Seal

Tell every prescriber, and the pharmacist, the full list. Half of American adults take a dietary supplement — 52% in the 2011–2012 national survey, with fish-oil use having risen from 1.3% to 12% and vitamin D from 5.1% to 19% in a decade (Kantor 2016) — and most of them never mention it. Among adults taking prescription medicines who also took non-vitamin supplements, 69% had not discussed the supplements with any conventional practitioner in the past year; the products they were taking were echinacea, ginseng, ginkgo, garlic and glucosamine — two of them on the warfarin list above (Gardiner 2006). In the 2012 National Health Interview Survey, 42.3% of people using complementary approaches had not told their primary-care physician about the one they used most (Jou 2016). The commonest reasons are not secrecy: nobody asked, and it did not seem like medicine. But every interaction in section 6 is invisible to a doctor who does not know the supplement is there, and a pharmacist can run your complete list through the same interaction database that the researchers in section 7 used, in a minute, for free.

How to do it so that it works: keep one list, on your phone, of every product and its dose — a photograph of each label is enough — and include the ones that do not feel like supplements: the sleep gummy, the pre-workout powder, the “immune” shot, the protein bar with added vitamins. Bring the bottles to any new prescriber. Ask the pharmacist, directly, “Does anything on this list interact with my prescriptions?” And when a prescription changes, ask again, because the answer changes with it.

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9. What to Do When Something Goes Wrong

The symptoms that should make you act rather than wait: chest pain, a racing or irregular heartbeat, fainting or a blood pressure that will not come up; severe abdominal pain, vomiting, dark urine or yellowing eyes; unusual bruising or bleeding in anyone on a blood thinner; agitation, sweating, tremor, high temperature or confusion in anyone who combined two serotonin-raising products; and any severe symptom in a child who may have swallowed pills.

  1. Stop every supplement, not just the one you suspect. Interactions are between products, and the guilty one is often not the obvious one.
  2. Call Poison Control: 1-800-222-1222. It is free, confidential, staffed around the clock by specialists, and it is the right call for “I took this and feel wrong” long before it is an emergency. The same service runs an online tool, webPOISONCONTROL at poison.org. For collapse, chest pain, a seizure or trouble breathing, call 911.
  3. Keep the bottle. The lot number is how a product gets traced and tested, and the label is how the emergency department learns what you took. Photograph the whole label, including the lot number and the expiry date, before anything else happens to the bottle.
  4. Report it to the FDA. For dietary supplements the FDA asks consumers to stop the product and file a report through its Safety Reporting Portal, explained on its How to Report a Problem with Dietary Supplements page; the general route is MedWatch’s online reporting form (Form FDA 3500B is the consumer version), or the FDA information line, 1-888-INFO-FDA (1-888-463-6332), pressing 2 for MedWatch. Manufacturers are required to report serious adverse events; consumers are not, and that is why the record is so thin — the hidden-drug products in section 5 were caught because somebody reported them.
  5. Tell your prescriber and ask for the right test. After a bodybuilding, weight-loss or green-tea-extract product, that is a liver panel (see Liver Function Tests); on warfarin, an INR; after a heavy-metal-suspect product such as an imported Ayurvedic or traditional remedy, a blood lead or mercury level (see Toxic Minerals).

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10. The Honest Bottom Line

Most supplements are what they say they are, and most of the people taking them come to no harm. The roughly 23,000 emergency visits a year (Geller 2015), set against the half of all adults who take something, make any single bottle a small risk. But the risk is not spread evenly, and that is the useful fact. It clusters in a few categories that this section maps page by page: products sold for sexual enhancement, weight loss and muscle building, which held 98% of the hidden drugs the FDA found in ten years (Tucker 2018); imported “herbal” arthritis remedies with steroids and painkillers inside; bodybuilding and weight-loss products and green-tea extract for the liver; megadose vitamins and minerals taken in overlapping products; and traditional remedies carrying lead, mercury or arsenic. Outside those categories the bottle is usually what it says, and inside them the label is the last thing to trust.

So the method is short. Learn the categories from the Dangerous Supplements hub. For anything you decide to take, look up a named certification in the certifier’s own database rather than trusting a printed seal, read the panel for serving size, proprietary blends and the Upper Limit, spend two minutes in the FDA’s records, and then tell the pharmacist and every prescriber what you are taking. A certification tells you the bottle is what it claims; the pharmacist conversation tells you whether it is safe next to your medicines. Between them they remove most of the risk that a “safe brands” list only pretends to.

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Research Papers

  1. Crawford C, Avula B, Lindsey AT, et al. Analysis of Select Dietary Supplement Products Marketed to Support or Boost the Immune System. JAMA Network Open. 2022;5(8):e2226040. doi:10.1001/jamanetworkopen.2022.26040 — 30 immune products bought on Amazon: 17 mislabelled, 13 missing listed ingredients, 9 with undeclared substances, none with a certification seal.
  2. LeBlanc ES, Perrin N, Johnson JD Jr, et al. Over-the-Counter and Compounded Vitamin D: Is Potency What We Expect? JAMA Internal Medicine. 2013;173(7):585-586. doi:10.1001/jamainternmed.2013.3812 — over-the-counter vitamin D pills contained 9% to 146% of the labelled dose.
  3. Erland LAE, Saxena PK. Melatonin Natural Health Products and Supplements: Presence of Serotonin and Significant Variability of Melatonin Content. Journal of Clinical Sleep Medicine. 2017;13(2):275-281. doi:10.5664/jcsm.6462 — 31 products: −83% to +478% of label, up to 465% lot-to-lot variation, serotonin in eight.
  4. Albert BB, Derraik JGB, Cameron-Smith D, et al. Fish oil supplements in New Zealand are highly oxidised and do not meet label content of n-3 PUFA. Scientific Reports. 2015;5:7928. doi:10.1038/srep07928 — only 3 of 32 products met their labelled EPA+DHA; 83% exceeded recommended peroxide values.
  5. Ichim MC. The DNA-Based Authentication of Commercial Herbal Products Reveals Their Globally Widespread Adulteration. Frontiers in Pharmacology. 2019;10:1227. doi:10.3389/fphar.2019.01227 — 27% of 5,957 herbal products adulterated by DNA testing; replaces the retracted 2013 barcoding study.
  6. Holbrook AM, Pereira JA, Labiris R, et al. Systematic Overview of Warfarin and Its Drug and Food Interactions. Archives of Internal Medicine. 2005;165(10):1095-1106. doi:10.1001/archinte.165.10.1095 — 181 reports on 120 drugs and foods; 72% potentiated warfarin; most were single case reports of poor quality.
  7. Booth SL, Golly I, Sacheck JM, et al. Effect of vitamin E supplementation on vitamin K status in adults with normal coagulation status. American Journal of Clinical Nutrition. 2004;80(1):143-148. doi:10.1093/ajcn/80.1.143 — 1,000 IU vitamin E a day for 12 weeks raised PIVKA-II, indicating poorer vitamin K status, in two randomised trials.
  8. Buckley MS, Goff AD, Knapp WE. Fish Oil Interaction with Warfarin. Annals of Pharmacotherapy. 2004;38(1):50-52. doi:10.1345/aph.1D007 — INR rose from 2.8 to 4.3 within a month of doubling fish oil from 1 g to 2 g a day.
  9. Izzo AA, Ernst E. Interactions Between Herbal Medicines and Prescribed Drugs: An Updated Systematic Review. Drugs. 2009;69(13):1777-1798. doi:10.2165/11317010-000000000-00000 — 128 case reports and 80 trials; St John’s wort lowers levels of warfarin, cyclosporine and tacrolimus; ginkgo and garlic interact with warfarin in case reports.
  10. Henderson L, Yue QY, Bergquist C, et al. St John’s wort (Hypericum perforatum): drug interactions and clinical outcomes. British Journal of Clinical Pharmacology. 2002;54(4):349-356. doi:10.1046/j.1365-2125.2002.01683.x — CYP3A4/2C9/1A2 and P-glycoprotein induction lowering warfarin, cyclosporin, protease inhibitors, digoxin and oral contraceptives; serotonergic interaction with SSRIs and triptans.
  11. Ruschitzka F, Meier PJ, Turina M, et al. Acute heart transplant rejection due to Saint John’s wort. The Lancet. 2000;355(9203):548-549. doi:10.1016/S0140-6736(99)05467-7 — two transplant patients rejected after St John’s wort lowered their cyclosporine levels.
  12. Cheitlin MD, Hutter AM Jr, Brindis RG, et al. Use of Sildenafil (Viagra) in Patients With Cardiovascular Disease. Circulation. 1999;99(1):168-177. doi:10.1161/01.CIR.99.1.168 — ACC/AHA consensus: concurrent nitrate use is the setting in which sildenafil is clearly contraindicated.
  13. Turner EH, Loftis JM, Blackwell AD. Serotonin a la carte: Supplementation with the serotonin precursor 5-hydroxytryptophan. Pharmacology & Therapeutics. 2006;109(3):325-338. doi:10.1016/j.pharmthera.2005.06.004 — review of 5-HTP; safety section covers eosinophilia-myalgia syndrome and serotonin syndrome.
  14. Block KI, Koch AC, Mead MN, et al. Impact of antioxidant supplementation on chemotherapeutic toxicity: A systematic review of the evidence from randomized controlled trials. International Journal of Cancer. 2008;123(6):1227-1239. doi:10.1002/ijc.23754 — 33 trials, 2,446 patients: antioxidants mostly reduced toxicity; the trials did not measure recurrence or survival.
  15. Ambrosone CB, Zirpoli GR, Hutson AD, et al. Dietary Supplement Use During Chemotherapy and Survival Outcomes of Patients With Breast Cancer Enrolled in a Cooperative Group Clinical Trial (SWOG S0221). Journal of Clinical Oncology. 2020;38(8):804-814. doi:10.1200/JCO.19.01203 — antioxidants before and during chemotherapy: recurrence HR 1.41 (95% CI 0.98–2.04); B12 and iron significantly worse; multivitamin no association.
  16. Obeid R, Fedosov SN, Nexo E. Cobalamin coenzyme forms are not likely to be superior to cyano- and hydroxyl-cobalamin in prevention or treatment of cobalamin deficiency. Molecular Nutrition & Food Research. 2015;59(7):1364-1372. doi:10.1002/mnfr.201500019 — all B12 forms are converted to the same intracellular coenzymes; no evidence methylcobalamin is superior.
  17. Kantor ED, Rehm CD, Du M, et al. Trends in Dietary Supplement Use Among US Adults From 1999-2012. JAMA. 2016;316(14):1464-1474. doi:10.1001/jama.2016.14403 — 52% of U.S. adults used a supplement in 2011–2012; fish oil rose from 1.3% to 12%, vitamin D from 5.1% to 19%.
  18. Gardiner P, Graham RE, Legedza ATR, et al. Factors Associated With Dietary Supplement Use Among Prescription Medication Users. Archives of Internal Medicine. 2006;166(18):1968-1974. doi:10.1001/archinte.166.18.1968 — of prescription-medicine users also taking non-vitamin supplements, 69% had not discussed them with a conventional practitioner.
  19. Jou J, Johnson PJ. Nondisclosure of Complementary and Alternative Medicine Use to Primary Care Physicians: Findings From the 2012 National Health Interview Survey. JAMA Internal Medicine. 2016;176(4):545-546. doi:10.1001/jamainternmed.2015.8593 — 42.3% of users had not disclosed their most-used complementary approach to their primary-care physician.
  20. Qato DM, Wilder J, Schumm LP, et al. Changes in Prescription and Over-the-Counter Medication and Dietary Supplement Use Among Older Adults in the United States, 2005 vs 2011. JAMA Internal Medicine. 2016;176(4):473-482. doi:10.1001/jamainternmed.2015.8581 — 15.1% of adults aged 62–85 at risk of a major drug–drug interaction in 2010–2011, up from 8.4%; supplement use 51.8% to 63.7%.
  21. Geller AI, Shehab N, Weidle NJ, et al. Emergency Department Visits for Adverse Events Related to Dietary Supplements. New England Journal of Medicine. 2015;373(16):1531-1540. doi:10.1056/NEJMsa1504267 — an estimated 23,005 emergency visits a year; unsupervised child ingestion and pill-swallowing problems in older adults among the leading causes.
  22. Tucker J, Fischer T, Upjohn L, et al. Unapproved Pharmaceutical Ingredients Included in Dietary Supplements Associated With US Food and Drug Administration Warnings. JAMA Network Open. 2018;1(6):e183337. doi:10.1001/jamanetworkopen.2018.3337 — 776 products with unapproved drugs in FDA warnings 2007–2016, concentrated in sexual enhancement, weight loss and muscle building.
  23. Cohen PA, Maller G, DeSouza R, et al. Presence of Banned Drugs in Dietary Supplements Following FDA Recalls. JAMA. 2014;312(16):1691-1693. doi:10.1001/jama.2014.10308 — about two-thirds of supplements re-purchased after an FDA recall still contained the banned drug.
  24. Navarro VJ, Barnhart H, Bonkovsky HL, et al. Liver injury from herbals and dietary supplements in the U.S. Drug-Induced Liver Injury Network. Hepatology. 2014;60(4):1399-1408. doi:10.1002/hep.27317 — herbals and supplements about 16% of drug-induced liver injury cases, and rising.
  25. Manoguerra AS, Erdman AR, Booze LL, et al. Iron Ingestion: an Evidence-Based Consensus Guideline for Out-of-Hospital Management. Clinical Toxicology. 2005;43(6):553-570. doi:10.1081/CLT-200068842 — poison-centre triage of iron ingestion by milligrams of elemental iron per kilogram of body weight.

Regulatory Records / Certification Programmes

  1. U.S. Pharmacopeia, Dietary Supplements Verification Program — usp.org/verification-services/dietary-supplements-verification-program; consumer site with the four verification points and the product finder: quality-supplements.org.
  2. NSF, Dietary Supplement and Vitamin Certification (NSF/ANSI 173 and NSF Certified for Sport) — nsf.org/consumer-resources/articles/supplement-vitamin-certification; Certified for Sport product search: nsfsport.com/certified-products.
  3. LGC, Informed Sport (every batch tested, search by batch number) — sport.wetestyoutrust.com; Informed Choice, retail monitoring — choice.wetestyoutrust.com/about/sport-vs-choice (LGC’s own comparison of the two programmes).
  4. BSCG Certified Drug Free — programme description: bscg.org/drug-testing-and-supplement-certification; tested-lot database: bscg.org/certified-drug-free-database.
  5. ConsumerLab.com, About ConsumerLab (how products are purchased and tested; Quality Certification Program) — consumerlab.com/about.
  6. FDA, Health Fraud Product Database — fda.gov/consumers/health-fraud-scams/health-fraud-product-database; category lists: Medication Health Fraud Notifications.
  7. FDA, Recalls, Market Withdrawals and Safety Alerts — fda.gov/safety/recalls-market-withdrawals-safety-alerts.
  8. FDA, MedWatch: Reporting Serious Problems to FDA (online form, Form FDA 3500B, 1-888-INFO-FDA) — fda.gov/safety/medwatch-fda-safety-information-and-adverse-event-reporting-program/reporting-serious-problems-fda; supplements route via the Safety Reporting Portal: How to Report a Problem with Dietary Supplements.
  9. FDA, Dietary Supplement Labeling Guide — fda.gov/food/dietary-supplements-guidance-documents-regulatory-information/dietary-supplement-labeling-guide; Daily Values used for %DV: Daily Value on the Nutrition and Supplement Facts Labels.
  10. 21 CFR 101.36, Nutrition labeling of dietary supplements (paragraph (c), proprietary blends; paragraph (b)(1), serving size) — ecfr.gov, 21 CFR 101.36.
  11. NIH Office of Dietary Supplements, Dietary Supplement Fact Sheets (RDAs and Tolerable Upper Intake Levels for every vitamin and mineral) — ods.od.nih.gov/factsheets/list-all.
  12. Poison Control, 1-800-222-1222 and webPOISONCONTROL — poison.org.

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