How AI Search Is Recommending Sports Nutrition and Protein Supplements: Monthly Trends

Executive Summary

Optimum Nutrition remains the category leader in October 2026, recommended in 83.0% of qualified observations. The gap to the next brand has all but closed: Transparent Labs sits at 82.4%, a separation of just 0.6 points at the top of the vertical. That is the tightest the two leaders have been across the August 2026 to October 2026 series, down from a 6.7-point gap in August 2026 and a 1.9-point gap in September 2026.

Transparent Labs was the month's strongest upward mover and the only brand classified as a significant riser, gaining 4.3 points from 78.1% in August 2026 to 82.4% in October 2026. Its top-three recommendation rate climbed 12.2 points over the same span, and its rank-one rate rose to 37.0%. The brand's coverage has risen in each month of the series.

The steepest declines over the series were BSN and MuscleTech, both classified as significant decliners. BSN fell 3.0 points from 8.2% in August 2026 to 5.2% in October 2026, while MuscleTech dropped 4.1 points from 11.8% to 7.7%. Both lost ground against the leader every month.

Against September 2026, however, October 2026 was quiet: no brand moved significantly versus the prior month, and the category summary describes the month as mixed. The top two leaders are converging, the mid-tier is drifting apart, and the overall structure of the vertical held firm across all three months.

Each monthly run begins with 800 prompt-surface observations, across the benchmark's defined AI/search surface universe. In August 2026 those 800 prompts covered 626 unique questions; in September 2026, 629 unique questions; and in October 2026, 591 unique questions. In all three months, all 800 prompts mentioned a tracked brand or competitor. Relevant prompts numbered 794 in August 2026 with 6 irrelevant, 796 relevant with 4 irrelevant in September 2026, and 796 relevant with 4 irrelevant in October 2026. The public metrics use the qualified observation counts of 684 for August 2026, 695 for September 2026, and 692 for October 2026 that survive both qualification stages.

Key Findings

AI Response Inconsistency Alerts

Questions This Section Answers

• Where did AI platforms disagree about whether GNC stocks or sells Transparent Labs?
• What sources did the conflicting AI answers cite for the GNC and Transparent Labs availability question?

Three critical factual inconsistencies were detected across three AI platforms, all concerning whether GNC stocks or sells Transparent Labs products. Each conflict was recorded at critical severity with full confidence, and in every case the disagreement concerns the same underlying availability question.

GNC

When asked "Does GNC stock Transparent Labs?", Copilot stated that GNC does not stock Transparent Labs supplements, citing the Transparent Labs store locator, a Fitness Volt review, and a Garage Gym Reviews protein review. Perplexity answered the same question affirmatively, stating that GNC has carried Transparent Labs products in some locations and periods, referencing Instagram and Facebook posts that announced Transparent Labs products arriving at GNC locations. This is a critical availability conflict: one answer denies any GNC stocking while the other affirms it.

A second critical inconsistency on the same topic set Google AI Overviews against Copilot. Asked "Does GNC stock Transparent Labs?", Google AI Overviews stated that GNC carries select Transparent Labs products in stores and online, citing an Instagram post announcing a GNC drop, an Instacart GNC listing for Transparent Labs whey protein isolate, and the Transparent Labs store locator. Copilot returned the opposite claim, that GNC does not stock Transparent Labs supplements, citing the Transparent Labs store locator, a Fitness Volt review, and a Garage Gym Reviews review. The two responses cannot both be true.

A third critical inconsistency concerned availability of Transparent Labs at GNC. Asked "Does GNC sell Transparent Labs?", Google AI Overviews stated that GNC sells Transparent Labs products in select physical retail stores, citing Instagram posts announcing the brand's arrival at specific GNC locations. Copilot stated that GNC does not sell Transparent Labs supplements and that they are not distributed in GNC retail stores or on GNC's online platform, citing the Transparent Labs store locator, a Supplementscience brand page, and a Protein Supply brand profile. The flagged sources in this case included Instagram posts describing Transparent Labs as now available at named GNC stores.

Across all three conflicts, the disagreement centres on whether Transparent Labs products are carried through GNC retail. The platforms citing first-party and social retail announcements answered affirmatively, while Copilot's answers drew on the brand's own store locator and third-party review pages.

Benchmark Context

The report separates the raw collection universe from the qualified analysis set. Brand-level recommendation percentages are calculated within the qualified benchmark set.

The September 2026 run sat between these two points, with 695 qualified observations and 629 unique questions, and the qualified observation count has held within an 11-observation band across the series.

Benchmark-Level Metrics

The valid recommendation shortlist share of 94.8% in October 2026 is the highest of the three months, up from 90.8% in September 2026. The recommendation-shaped answer share peaked in September 2026 at 62.7% before easing back in October 2026.

AI Recommendation Trend

Questions This Section Answers

• How narrow is the gap between Optimum Nutrition and Transparent Labs in October 2026?
• Which brands moved significantly against the August 2026 baseline, and in which direction?
• What separates Transparent Labs' rise from the movement of the mid-tier brands?

The Top Two Have Converged While the Mid-Tier Drifts Further Behind

Optimum Nutrition and Transparent Labs are now separated by just 0.6 points, the narrowest margin in the series. Transparent Labs is the only brand whose coverage moved significantly against the August 2026 baseline, and the two significant decliners, BSN and MuscleTech, sit more than 70 points behind the leaders.

Transparent Labs is the only brand whose baseline-to-current movement exceeds the normal month-to-month variation for the vertical, while BSN and MuscleTech are the only two significant decliners. The category-level change across the series therefore reflects one brand's sustained rise against two brands' sustained losses, with the remaining seven brands holding steady.

What Changed This Month

Questions This Section Answers

• Why did Optimum Nutrition's lead narrow even as its rank-one rate rose?
• What drove Transparent Labs' significant coverage gain this month?
• Which prompt categories lost BSN and MuscleTech presence?

Optimum Nutrition

Optimum Nutrition led the category in October 2026 with 83.0% valid recommendation coverage, down 1.8 points from 84.8% in August 2026 but only 0.3 points below its September 2026 reading of 83.3%. The brand remains the reference point for the vertical, though its lead has narrowed to its smallest margin in the series.

Placement held firm even as coverage eased. Optimum Nutrition's top-three recommendation rate rose 3.2 points against the August 2026 baseline, to 75.1%, and its rank-one rate rose 2.6 points to 41.6%. The brand was present in 620 of 692 qualified observations in October 2026, down from 638 of 684 in August 2026, and its raw mention presence rate fell 3.7 points to 89.6% over the same span.

The distinction worth noting is that this is a presence story, not a placement story. Optimum Nutrition is being surfaced in slightly fewer conversations while converting more of the conversations it does appear in into top-three and rank-one recommendations. Highest-priority diagnostic: which prompt categories lost the brand's presence, and whether those same categories are where Transparent Labs gained.

Transparent Labs

Transparent Labs posted the only significant rise in the series, with valid recommendation coverage up 4.3 points from 78.1% in August 2026 to 82.4% in October 2026. The gain was 1.0 point against September 2026, and the brand's coverage has risen in every month of the series.

The rise is concentrated in placement rather than mere presence. Its top-three recommendation rate climbed 12.2 points from 62.9% in August 2026 to 75.1% in October 2026, the largest supporting movement of any brand in the series. Rank-one placement rose 4.4 points to 37.0%, and raw mention presence rose 2.7 points to 84.4%, with the brand present in 584 of 692 qualified observations in October 2026.

Transparent Labs now matches Optimum Nutrition's 75.1% top-three rate exactly across the series, while trailing by 4.6 points on rank-one wins. That is the distinction to watch: the two brands are being shortlisted together at the same rate, and the remaining separation sits at the top of the list. Highest-priority diagnostic: which prompts have seen Transparent Labs move from a top-three mention to the rank-one recommendation, and which surfaces carry that shift.

BSN

BSN's valid recommendation coverage fell 3.0 points from 8.2% in August 2026 to 5.2% in October 2026, classified as a significant decline. The October 2026 reading is a further 0.7 points below its September 2026 figure of 5.9%, and the brand has declined in each month of the series.

The decline shows in both presence and placement. Its raw mention presence rate fell 3.2 points to 7.2%, and its top-three recommendation rate fell 2.8 points to 1.9%. BSN recorded no rank-one recommendations in October 2026, down from a 0.3% rate in August 2026, and its valid recommendation count stood at 36 of 692 qualified observations.

With counts this small, a handful of observations moves the percentage materially. The commercial signal is that BSN is appearing in fewer conversations and converting fewer of those appearances into shortlist placements, with the rank-one position now absent entirely. Highest-priority diagnostic: which prompt categories previously surfaced BSN, and which brand now occupies those recommendation slots.

MuscleTech

MuscleTech declined 4.1 points from 11.8% in August 2026 to 7.7% in October 2026, the largest significant drop in the series. Its October 2026 reading is 0.4 points below September 2026, meaning the second month of the decline was modest and the bulk of the loss occurred between August and September 2026.

The loss is best described as a presence problem. MuscleTech's raw mention presence rate fell 5.7 points to 10.1%, while its top-three rate fell 2.3 points to 4.6%. The brand recorded no rank-one recommendations in October 2026, down from 0.7% in August 2026. It was present in 70 of 692 qualified observations, with 53 valid recommendations.

MuscleTech retains top-three placement at a higher rate than BSN or Kaged despite lower coverage than either's baseline, which suggests its remaining appearances are reasonably strong. Highest-priority diagnostic: which prompt categories drove the loss of presence, and whether the competitor gaining there is Transparent Labs or a brand closer to MuscleTech's own coverage band.

GNC

GNC's valid recommendation coverage moved from 2.8% in August 2026 to 4.0% in October 2026, a change that falls within normal month-to-month variation for the brand, which remains ninth by coverage. The October 2026 figure is 1.7 points above its September 2026 reading of 2.3%.

The movement is driven by presence. GNC's raw mention presence rate rose 6.1 points to 28.6%, meaning the brand was present in 198 of 692 qualified observations. Top-three placement rose just 0.9 points to 2.8%, and rank-one rose 0.1 points to 1.0%.

This is the vertical's clearest example of the gap between being mentioned and being recommended. GNC is surfaced in more than a quarter of qualified observations and recommended to a shortlist position in under 3% of them, the widest such divergence among the tracked brands. Its neutral sentiment reading of 0.1 is also the lowest in the vertical. Highest-priority diagnostic: what the AI systems say about GNC in the observations where it appears but is not recommended, and which surface families carry that presence.

Category-Level Gap Widening

Three gaps widened in every month of the series, each separating a lower-coverage brand from Transparent Labs. The MuscleTech-to-Transparent Labs gap widened by 8.4 points, from 66.3 points in August 2026 to 74.7 points in October 2026. The BSN-to-Transparent Labs gap widened by 7.3 points, from 69.9 to 77.2 points. The Kaged-to-Transparent Labs gap widened by 6.7 points, from 69.8 to 76.5 points.

These are category observations about repositioning rather than single-brand problems. As the top two converge, the distance between the top two and the lower half of the vertical is growing in the same months.

Buyer-Intent Interpretation

Questions This Section Answers

• Which buyer-intent clusters carry qualified observations in October 2026?
• What can the benchmark not yet say about pricing and head-to-head brand comparisons?

All 692 qualified observations in October 2026 fell into the Brand Recommendation cluster, following the same pattern as August 2026 and September 2026, where all qualified observations also fell into that cluster. The Pricing & Value and Multi-Brand Comparison clusters carry no qualified observations in any month of the series.

The implication is that the public benchmark can speak to which brands AI systems recommend, but it cannot yet answer how AI frames price and value, nor how brands fare in direct head-to-head comparison queries. The response-type distribution in October 2026 shows 20 comparison analysis responses and 11 pricing analysis responses in the raw collection, but these did not qualify for cluster-level analysis in the public benchmark. Those buyer-intent classes remain a gap in the current public evidence base.

Brand Opportunity Summary

Questions This Section Answers

• Which brands need the most urgent diagnostic attention, and what is the specific question to investigate for each?
• Why does GNC's 28.6% presence convert to only 4.0% recommendation coverage?

The benchmark identifies where attention is warranted; a company-level analysis is needed to explain why.

Evidence Behind the Benchmark

The aggregate metrics are built from prompt-level observations (query, surface, recommendation outcome, rank, sentiment, and citations where exposed). Company-level analysis can go deeper into prompt, competitor, surface, and evidence patterns. Source presence is not automatically treated as proof of causation.

About This Benchmark

This report is part of CiteWorks Studio's AI Visibility Market Discovery research program.

• AI Visibility Industry Market
• AI Visibility Industry Market Methodology
• AI Visibility Industry Market Metrics
• AI Visibility Industry Market Standards

Report-Specific Interpretation Notes

• Movement between months is directional analysis that identifies changes worth investigating; it does not by itself establish the cause of those changes.
• Small absolute counts for brands such as Muscle Milk (14 valid recommendations in October 2026), GNC (28), and BSN (36) mean percentage movements can appear larger than their commercial weight.
• The qualified benchmark set of 692 observations in October 2026 is the public denominator for all brand-level metrics, not the raw collection of 800 prompts.
• Raw mention presence and valid recommendation coverage are distinct signals; GNC demonstrates the widest divergence between the two in this vertical, present in 28.6% of observations and recommended in 4.0%.
• Presence, coverage, rank, and sentiment are reported as separate signals and should not be read as interchangeable.

Next Step

The Public Benchmark Shows Where a Brand Is Winning or Losing. A Company-Level Audit Shows Why.

The aggregate percentages in this report only reveal the surface of AI recommendation behavior. Beneath them sit questions with direct commercial consequences: which high-intent prompts is a brand winning or losing, which competitor takes the recommendation when a brand loses, what attributes AI systems associate with each option, and which external sources shape those answers in ways that differ across ChatGPT, Copilot, Gemini, Perplexity, AI Overviews, and AI Mode.

A company-specific AI visibility audit maps those prompt, surface, competitor, ranking, sentiment, and evidence-source patterns into a prioritized visibility strategy. Rather than reacting to monthly percentage movements, an audit identifies the specific queries and surfaces where intervention will have the greatest impact.

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