AEO INDEX OCTOBER 2026 USA: Thorne is the supplement brand AI names first most often, and two-thirds of ChatGPT’s supporting sources are independent blogs
Thorne won four of ten supplement questions. Five other brands won one product each, and Gemini cited sources in only two of its ten answers.
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Thorne was the first brand named in 8 of the 30 AI answers we collected about supplements and vitamins, more than any other of the 51 brands that ChatGPT, Gemini and Google AI Overviews mentioned. It won four of the ten questions: multivitamins, creatine, vitamin D and magnesium.
The sourcing behind those answers is thin in places. ChatGPT took 66.2% of its citations from independent blogs and other publishers, and 10.8% from health reference sites such as Healthline. Gemini wrote the longest answers, about 1,127 words on average, yet cited sources in only two of its ten, six citations in total. We collected the answers on 21 October 2026 from one U.S. location, and every table is in the full October 2026 report.
Which brand does AI put first?
Thorne leads with an AI Rank Score of 43.0. The score weights how high a brand appears in each answer and runs from 0 to 100, where 100 would mean first place on all three engines for every question. Transparent Labs is second at 30.7. Optimum Nutrition is third at 18.3, and no other brand clears 20.
Thorne’s four wins are not equally strong. Magnesium was a clean sweep at 100. Vitamin D was the narrowest, at 60, and each engine picked a different first brand there: Thorne on ChatGPT, Nature Made on Gemini and Sports Research on AI Overviews. Gemini was the only engine to name Nature Made on that question at all.
Transparent Labs was named in 43% of answers, second to Thorne’s 57%, and came first in three. It won pre-workout, was second on protein powder, and was the brand Google AI Overviews named most. Garden of Life was named in 27% of answers and was not ranked first in any of them.
Why do so many brands win only one question?
Five brands besides Thorne and Transparent Labs each won a single product type:
- Protein powder: Optimum Nutrition, 100.
- Omega-3 fish oil: Nordic Naturals, 100.
- Collagen: Vital Proteins, 100.
- Greens powder: AG1, 100.
- Probiotics: Culturelle, 93. AI Overviews chose Ritual first instead.
None of the five appears in more than 23% of all answers. AG1, Vital Proteins and Culturelle are each named in 10%. That is three answers apiece, the one question each of them won.
The three engines agreed on the first brand for five of the ten questions. On creatine, AI Overviews picked Transparent Labs and the other two picked Thorne. Gemini went with Gorilla Mode on pre-workout and Nature Made on multivitamins.
Some familiar names were missing. No engine named Olly for multivitamins, Isopure or Premier Protein for protein powder, or Nature’s Bounty or Kirkland for vitamin D. Garden of Life was missing from greens powders, one of the five questions where it was expected.
Where do these answers come from?
The engines cited 140 sources from 85 websites, and only 7 citations (5%) went to brands’ own sites. healthline.com and forbes.com were cited 9 times each, youtube.com 8 times and usnews.com 7 times. AI Overviews leaned hardest on editorial outlets, 39.1% of its citations, and also cited amazon.com and fortune.com five times each.
What we can’t tell from the data is how each engine weighs a blog roundup against a health reference page, or whether it checked any claim on either.
What does this mean for supplement brands?
In my view, supplements are the clearest case for picking your question. Optimum Nutrition, Nordic Naturals, Vital Proteins and AG1 each own one product query with a perfect score and show up in few other answers. Broad mentions across many questions are a separate result, and the index scores them separately.
The sourcing should worry brand and PR teams more than the rankings. Most of ChatGPT’s citations are blogs, and Gemini barely cites anything. That gives the third-party roundups that rank supplements a lot of weight in what the engines say. I’d start by finding out which of those pages get cited.
What to watch in November
Vitamin D is the one I’d track. Three engines named three different brands first in October, and the November edition will show whether any of them settles in. The index analysis is powered by markaeo.com, and the complete data is in the full October 2026 report.
How we measured: we asked ChatGPT, Gemini and Google AI Overviews 10 buying questions, 30 answers in all, collected on 21 October 2026 from a single U.S. location. AI answers vary by time, place and user. The full method and notice are in the report.
Sources
- Answer Engine Daily AEO Index: Supplements & Vitamins, October 2026
