Your brand sells on Amazon, Costco, and through subscription. AI thinks you're only on one.

What the data actually says

61 unique brands surfaced across the three channel prompts. The coverage distribution is sharp:

Zero brands span the full retail map. Eight brands span two of three. Fifty-three sit in a single channel context.

The channel-locked roster is concrete and named in the data:

Costco-locked. Kirkland Signature (5 of 5 platforms), Pure Alaska Omega, Nature's Bounty, Further Food, Nature's Lab Gold. Premium DTC brands like Thorne and Transparent Labs are absent from Costco prompts.

Amazon-locked. NOW Foods, Centrum, Bronson Vitamins, Double Wood Supplements, Amazon Basics, Amazon Elements. Practitioner-only brands (Pure Encapsulations, Designs for Health) do not surface here.

Subscription-locked. HUM Nutrition (5 of 5 platforms), Persona Nutrition, Ritual, Perelel, VitaminLab, Bioniq, Rootine, Future Kind. Mass-market multivitamins are absent.

The contradiction worth documenting

The most useful data points are the brands that physically sell across channels but appear AI-locked to one. We pulled three from the source data:

• NOW Foods ships the same product line on Amazon and through subscription services. AI mentions NOW Foods only in Amazon context.
• Thorne is a top-3 brand overall by score (92), sold practitioner-direct, on Amazon, and via subscription. In channel queries, AI places Thorne only in subscription context.
• Centrum is sold everywhere physically — pharmacy, grocery, mass retail, Amazon, Costco. AI places Centrum only in Amazon context.

Three brands, three different real-world channel mixes, three single-channel AI identities. The pattern is not about whether the brand sells on multiple channels.

Why this happens

AI brand identity is anchored to where the brand has editorial coverage, not where it sells. Costco-locked brands are the ones that show up in “best Costco supplement” listicles on Fortune, Good Housekeeping, and category roundup sites. Amazon-locked brands are the ones that show up in Amazon Best-Sellers analyses, supplysidesj.com Amazon-brand breakdowns, and product-review sites that index Amazon's marketplace. Subscription-locked brands are the ones covered in subscription-service review articles and DTC-focused women's-health publishers.

NOW Foods has subscription distribution, but the publishers writing about NOW Foods write in Amazon-marketplace context. Thorne sells on Amazon, but the publishers writing about Thorne write in practitioner-grade and subscription context. Centrum sells everywhere physically, but the high-citation articles featuring Centrum frame it as an Amazon-tier mass multivitamin.

AI reads the editorial signal, not the retail SKU map. Where the publishers place you is where AI places you.

The 8-brand exception

Eight brands span two of three channel contexts. They are the brands a cross-channel supplement marketer should study before anything else, because they are doing the thing the 53 channel-locked brands are not. From the dataset, these are brands with category coverage on more than one channel-specific publisher set: Costco-related listicles AND Amazon-related, or Amazon-related AND subscription-related. Vital Proteins and AG1, for example, surface in both Costco and Amazon contexts. Sports Research surfaces in Costco and Amazon. Ritual and HUM appear in subscription and in broader trust-cert and women's-health prompts that brush adjacent to Amazon's mass-market frame.

The common move across the 2-of-3 brands is publisher-coverage diversification, not retail-distribution diversification. They earned editorial placement on more than one channel-specific surface — not because they sell on more channels, but because they pursued category coverage in more than one channel-specific publisher universe.

What this means for cross-channel brands

Three concrete moves emerge directly from the data:

1. Audit your channel-locked AI identity. Before anything else, run the same three channel prompts against ChatGPT, Claude, and Perplexity for your brand: “best supplements at Costco”, “best supplements on Amazon”, “best subscription supplement services”. Note which AI engine puts you in which channel — they often disagree. If the answer is “Amazon-only” across all three engines, you have an Amazon-locked AI identity that does not match your retail reality. The audit is the entry point because most cross-channel brands have not actually checked.
2. Channel positioning is content strategy, not retail strategy. Adding a Costco SKU does not produce Costco AI mentions. What produces Costco AI mentions is editorial coverage on the publisher set that gets cited in Costco-context prompts: Costco-related listicles, “best things to buy at Costco” roundups, mass-warehouse value analyses. The same logic applies to Amazon (Best-Sellers analyses, supplysidesj.com Amazon coverage, marketplace product reviews) and to subscription (DTC review sites, women's-health publisher subscription roundups, comparison articles between subscription services). Earn coverage on each channel-specific publisher universe you want AI to associate you with. Distribution alone does not move the needle.
3. Study the 8 brands that span 2 of 3 channels. Pick the two from the cross-channel exception group closest to your category — for an omega-3 brand, that is Sports Research and Vital Proteins; for a women's-health brand, Ritual and HUM. Map their publisher-coverage footprint by channel context. The publishers covering them across channel contexts are the publishers a third cross-channel brand would target to break out of single-channel lock-in. The benchmark is replicable, and it is the difference between brands that AI sees as one-channel and brands AI sees as multi-channel.

A note on category breadth. Subscription-context brands skew DTC-native and women's-health. Costco-context brands skew value and mass-multivitamin. Amazon-context brands are the broadest, since Amazon marketplace coverage is the most editorially diverse. Spanning Costco and subscription is a harder content lift than spanning Amazon and one other channel.