What AI Search Recommends for US Supplement Buyers

Executive summary

Thorne, Pure Encapsulations, and NOW Foods take 48% of all AI supplement cites. Third-party testing (NSF, USP, Informed Sport) is the single largest differentiator.
AI refuses to recommend supplements for serious conditions. All four engines hedge heavily on anything pitched as treating disease. The brands that win trust queries publish Certificate of Analysis documents and third-party testing per batch.
Claude is brutal on supplements. It will decline to recommend a brand that lacks third-party testing, lists proprietary blends, or makes structure-function claims without citations. 42% of our Claude prompts resulted in the engine actively steering away from a named brand.

How each engine behaves in US supplements

ChatGPT is r/Supplements, r/Nootropics, r/Nutrition, and Examine.com heavy. The engine reproduces Examine's ingredient-by-ingredient evidence ratings and the subreddit consensus. Brands absent from these discussions are invisible.

Claude is the harshest AI on supplements. It cites brands publishing third-party Certificate of Analysis documents, named testing labs (NSF, USP, Informed Sport, ConsumerLab), clear ingredient amounts without proprietary blends, and GMP certification. Claude will actively tell users to avoid brands with proprietary blends. Thorne, Pure Encapsulations, Jarrow, and NOW win disproportionately.

Gemini leans on Amazon review volume, iHerb, Walmart. For non-condition queries it tends to cite the most-reviewed product. For condition queries it suppresses supplement recommendations and pushes users to medical sources.

Perplexity cites Examine.com, Labdoor, ConsumerLab, Healthline, and clinical journal abstracts. Fifty-nine percent of sources came from these five. Perplexity is the most likely to surface independent lab testing results (Labdoor rankings especially).

Estimated citations per 100 prompts, blended:

Thorne 37 (ChatGPT 34, Claude 48, Gemini 32, Perplexity 35). Clinical positioning, third-party tested.
Pure Encapsulations 30. Practitioner-grade.
NOW Foods 28. Budget third-party tested.
AG1 / Athletic Greens 22. Cross-category greens powder.
Ritual 21. Women's vitamins DTC.
Nordic Naturals 19. Fish oil category default.
Momentous 16. Performance supplements.
Jarrow Formulas 14. Value-tier tested.
Life Extension 14. Longevity-positioned.
Garden of Life 13. Whole-food multivitamins.
Seed 13. Probiotic DS-01 dominant.
MaryRuth's 12. Liquid-forward DTC.
Klaire Labs 11. Practitioner probiotics.
Hum Nutrition 10. DTC women's vitamins.
Needed 9. Prenatal and postpartum.
Standard Process 8. Practitioner whole food.

Below 8: noise.

What the winners do that losers don't

Thorne teardown. Thorne is the reference brand in AI-supplement queries. Every SKU page publishes NSF Certified for Sport status when applicable, exact ingredient amounts (no proprietary blends), Mayo Clinic partnership references, and citations to clinical trials using the exact formulation. Thorne's Certificate of Analysis is downloadable per batch. Practitioner sales channel gives them clinical editorial credibility. Claude cites Thorne because Thorne publishes exactly what Claude demands.

Pure Encapsulations teardown. Nestlé Health Sciences owned, practitioner-distributed (originally). Every ingredient is named, amounts are explicit, hypoallergenic claims are third-party verified. The brand's positioning around "free-from" (free from wheat, gluten, magnesium stearate, artificial dyes) maps directly to Claude's filter preferences. Pure Encapsulations is the brand practitioners recommend in closed professional networks, and those recommendations leak into AI training data via medical Q&A sites.

AG1 teardown. AG1 (formerly Athletic Greens) is the outlier. Claude does not love AG1 (proprietary blend criticism) but ChatGPT and Gemini do (massive influencer seeding and strong review volume). AG1 wins through paid reach and podcast presence (Tim Ferriss, Huberman sponsored reads for years) more than through clinical rigor. The brand recently added Informed Sport certification to close the gap.

Prompt-type segmentation

Transactional ("best third-party tested multivitamin"): Thorne, Pure Encapsulations, NOW split.

Comparative ("Ritual versus Thorne multivitamin"): Thorne wins on rigor. Ritual wins on form factor and brand. Both have some versus content but rely mostly on editorial.

Educational ("what does magnesium glycinate do"): Examine.com and Healthline win. A brand publishing ingredient explainers gets scattered cites.

Trust ("is AG1 worth the money", "is collagen worth taking"): Claude hedges or steers away. Brands with third-party testing and clinical references win the few prompts where AI is willing to recommend.

Condition-specific ("supplements for perimenopause", "supplements for chronic fatigue", "supplements for thyroid"): AI almost always hedges. Brands with practitioner endorsement and published clinical data get occasional cites. Wide open category for condition-specific educational content.

Gap map

Brands under 5% AI share:

Designs for Health. Practitioner brand, cited in 3 of 28 despite clinical rigor. Cause: almost invisible to consumer-facing editorial.
Life Extension. Longevity positioning, cited in 8 of 28 but lost ground on proprietary blend issues.
Metagenics. Practitioner brand, cited in 2 of 28. Nearly invisible to consumer AI.
Ora Organic. Plant-based DTC, cited in 2 of 28.
Needed. Prenatal category, cited in 5 of 28. Needs more clinical study references.
Previnex. Physician-formulated joint and general, cited in 2 of 28.
Qunol. CoQ10 and turmeric, cited in 4 of 28. Strong retail presence, thin editorial.
Solgar. Legacy, cited in 6 of 28. Needs explicit third-party testing content.

Open queries no brand owns

"Supplements for perimenopause that are not just black cohosh". Open.
"Magnesium glycinate versus threonate versus citrate for sleep". Educational gap.
"Iron supplements for women that do not cause constipation". Hedged.
"Supplements for postpartum recovery beyond prenatals". Open.
"What to take if you are on Ozempic and losing muscle". Huge new segment, no brand answer.
"Supplements safe during radiation or chemo". AI refuses. Opportunity for practitioner-led content.
"Liver support supplements that are evidence-backed". Reddit only.

The 90-day playbook

1. Get NSF Certified for Sport, USP Verified, or Informed Sport (I5 / C4 / E2). The single most important credential. 3 to 6 months, real cost.

2. Publish Certificate of Analysis per batch on the product page (I5 / C5 / E3). Third-party lab name, actual versus claimed values, contaminant testing.

3. Eliminate proprietary blends or document each ingredient amount (I5 / C5 / E4). Claude will not cite proprietary blends.

4. Build a clinical-reference hub (I4 / C4 / E3). Ingredient-by-ingredient, with PubMed links. 20 to 30 pages.

5. Pitch Examine.com, Labdoor, ConsumerLab for independent review (I5 / C3 / E2). Labdoor rankings directly surface in Perplexity.

6. Build a practitioner advisory board (I4 / C3 / E2). Registered dietitians, MDs, functional medicine practitioners. Their endorsement drives Claude and trust-tier queries.

Methodology and appendix

Prompts tested: best third-party tested multivitamin, best fish oil, best magnesium for sleep, best vitamin D, best probiotic, best prenatal, best supplements for women over 40, best supplements perimenopause, best supplements men over 40, best creatine, best protein powder clean, best greens powder, best collagen powder, best ashwagandha, best turmeric, best omega-3 for kids, best iron supplement women, best supplements for immunity, best supplements for liver, best supplements thyroid, best supplements chronic fatigue, best supplements ADHD focus, best supplements anxiety, best supplements for athletes NSF, best multivitamin gummies, best glutathione supplement, best NAD precursor, best postpartum supplements. Engines: ChatGPT gpt-5, Claude sonnet-4-6, Gemini 2.5, Perplexity Sonar Pro.

Week 1 directional. Week 2 confirmed.

Next week

April 27 rerun. Reply with your domain for a SKU check.