Has the FDA issued warning letters for other keto or BHB-based supplements since 2020?

1. The government record: FDA posts warning letters but the supplied sources contain no post‑2020 keto/BHB example

The U.S. Food and Drug Administration maintains public pages that list warning letters related to foods, beverages and dietary supplements and a separate health‑fraud page with prior years’ letters ^{[1] [2]}, and the agency also highlighted a set of 2020 health‑fraud warning letters as examples ^[5]; none of the supplied FDA pages or excerpts identify a named warning letter issued since 2020 that specifically targets a keto or BHB supplement, so the sources do not provide direct evidence that the FDA issued such a warning in that timeframe ^{[1] [2] [5]}.

2. Industry and watchdog tools exist — but limitations in the archive and searchable tools leave gaps

Industry groups and third‑party trackers have compiled FDA warning‑letter data in the past (for example, the Council for Responsible Nutrition’s database), but that database stopped being updated and has known link problems after FDA website redesigns, meaning independent compilations cannot be relied on without cross‑checking the FDA’s live records ^[6]; the supplied material therefore flags the existence of tools to search warnings but also signals that those tools may not cover the most recent or reorganized FDA records ^[6].

3. Other authorities and reporting have singled out BHB products — but not as FDA warning letters in these sources

Outside the U.S. FDA record available here, other regulatory notices have named BHB‑branded products: for instance, a 2019 advisory from the Philippine Food and Drug Administration listed several unregistered supplements including a “SOZO KETO BOOST BHB” product, demonstrating that non‑U.S. regulators have taken public action regarding BHB supplements ^[4]; the supplied U.S. coverage and academic literature describe BHB as a widely used ingredient in exogenous‑ketone products and note safety and efficacy questions, but those articles do not substitute for an FDA warning letter ^{[7] [8] [9]}.

4. Consumer warnings and reporting emphasize scams and unproven claims around keto pills

Reporting from consumer health outlets and advocacy groups has repeatedly warned that keto diet pills and BHB supplements are frequently marketed with exaggerated claims and that scams surged around 2020–2024 — the FDA encourages caution for supplements pushed by pop‑ups and email, but the supplied consumer pieces and guides (U.S. News/AARP reporting) serve as consumer advisories rather than formal FDA enforcement documents naming specific keto/BHB firms ^{[10] [3]}.

5. What the sources can and cannot support — a transparent limitation

Based solely on the supplied sources, it is supportable to say the FDA routinely issues warning letters for dietary supplements and maintains public listings ^{[1] [2] [3]}, and that BHB/keto products have attracted regulatory attention globally and consumer‑facing warnings ^{[4] [10]}, but the materials provided do not include a cited FDA warning letter from 2020 onward that explicitly targets a keto or BHB product; absence of such an example in these sources should not be read as definitive proof that the FDA never issued any such letter after 2020, only that the supplied documents do not contain one ^{[1] [2]}.

6. Conclusion and how to verify further

To establish definitively whether the FDA has issued warning letters about keto or BHB supplements since 2020 requires searching the FDA’s live warning‑letter pages and health‑fraud archives by keyword (BHB, keto, ketone, exogenous ketone) or reviewing the FDA’s year‑by‑year warning‑letter listings and press releases, because the materials provided here document the FDA’s mechanism and examples but do not include any post‑2020 keto/BHB‑specific warning letter for the U.S. market ^{[1] [5] [2]}.