GLP3-B is a capsule sold online in the UK and across Europe as a food supplement. It is not retatrutide, the injectable trial drug nicknamed GLP3 or GLP-3, and by its sellers' own ingredient lists it contains no GLP-1 medicine. The listed formula is built around berberine, with guarana, inulin, two amino acids, zinc and chromium. One seller page states that GLP3-B "does not guarantee weight loss or any specific result". No clinical trial of the product was found.
| What it is | A food supplement in capsule form, taken once a day (per seller pages) |
|---|---|
| Main listed ingredient | Berberine HCl, 100 mg or 150 mg depending on the seller page |
| Contains retatrutide or a GLP-1 drug | Not according to any ingredient list reviewed |
| Clinical trials of the product | None found on PubMed or ClinicalTrials.gov (searched November 11, 2026) |
| Regulatory status | Sold as a food supplement, not as a medicine |
| Seller's statement on weight loss | It "does not guarantee weight loss or any specific result" |
What GLP3-B is
This article is based on three seller pages reviewed on November 11, 2026: one multi-language sales page and two UK online shop listings. All three describe GLP3-B as a supplement for adults, taken as one capsule a day. The sales page calls it "a food supplement, not a medicine" and says it "does not diagnose, treat or cure any condition". The two shop listings describe the product with appetite and weight-management wording.
That sales page also says it is an affiliate site that may earn a commission on orders, and that its operators are "neither the manufacturer, the distributor, nor the trademark holder of GLP3-B". It says the product is made in the EU at a facility that follows Good Manufacturing Practice standards. None of the three pages names the company that makes it.
GLP3-B ingredients, as listed by sellers
The sales page publishes this formula per capsule:
| Ingredient | Listed amount per capsule |
|---|---|
| Berberine HCl | 100 mg |
| Guarana extract (a source of caffeine) | 100 mg |
| Inulin from Jerusalem artichoke | 100 mg |
| L-glutamine | 50 mg |
| L-leucine | 50 mg |
| Zinc | 14 mg |
| Chromium | 40 micrograms |
The two UK shop listings name the same seven ingredients but give the berberine amount as 150 mg per daily dose, not 100 mg. This site has not tested the product and cannot say which figure is correct.
The sales page presents two statements as authorised EU health claims: that zinc contributes to normal carbohydrate metabolism, and that chromium contributes to the maintenance of normal blood glucose levels. Neither is a claim about weight loss. The same page says of berberine that "not all related claims are officially recognised at European level".
Is GLP3-B the same as GLP3 (retatrutide)?
No. "GLP3" and "GLP-3" are informal names for retatrutide, a drug candidate from Eli Lilly that has been tested as a once-weekly injection. GLP3-B shares part of the name and nothing else that could be verified. None of the three seller pages mentions retatrutide, GLP-1 or an injection.
| GLP3-B | Retatrutide (GLP3) | |
|---|---|---|
| What it is | Food supplement | Investigational drug, not FDA-approved |
| Form | Capsule taken by mouth each day | Injection under the skin once a week in trials |
| Active ingredient | Berberine, with guarana, inulin, amino acids, zinc and chromium | Retatrutide (LY3437943), one molecule that activates the GIP, GLP-1 and glucagon receptors |
| Clinical trials | None found for the product | Phase 2 and Phase 3 trials. TRIUMPH-1 randomized 2,339 adults |
| Reported weight change | None reported for the product | TRIUMPH-1: mean change of -17.6% to -25.0% at 80 weeks, against -3.9% with placebo (treatment-regimen estimand, which counts participants whether or not they stayed on the drug) |
| How it is obtained | Sold online without a prescription | Lilly says it is legally available only to participants in its clinical trials |
The retatrutide figures are group averages under trial conditions. They say nothing about a berberine capsule. For how the trial drug compares with approved medicines, see GLP-1 vs GLP-3.
Does GLP3-B work for weight loss? What berberine research shows
No study of GLP3-B itself was found. Searches of PubMed and ClinicalTrials.gov on November 11, 2026 returned no record for the product name. Any evidence therefore concerns its main listed ingredient, berberine, tested on its own.
The U.S. National Center for Complementary and Integrative Health (part of the NIH) describes the weight-loss evidence for berberine as "not conclusive". It summarizes a 2022 review in which effects on weight "were seen primarily in people who took berberine in doses of more than 1 gram per day and for more than 8 weeks", and notes that many of the studies had a high risk of bias. The GLP3-B seller pages list 100 mg to 150 mg of berberine a day, well below that 1 gram (1,000 mg) level. That comparison describes the research. It is not a suggestion to take more than the labelled amount.
Pooled analyses of randomized trials of berberine have reported small average changes, and they do not agree with each other:
- Asbaghi and colleagues, 2020 (12 trials): average body weight 2.07 kg lower with berberine than with control, and BMI 0.47 kg/m² lower.
- Elahi Vahed and colleagues, 2026 (23 articles): average body weight 0.88 kg lower. The authors point to blinding and randomization problems in the underlying trials and call for better reporting of the purity and potency of the berberine used.
- Xiong and colleagues, 2020 (10 studies): a small reduction in BMI and waist circumference, with no significant change in body weight.
- Amini and colleagues, 2020 (berberine and barberry, 12 trials, 849 participants): no significant change in body weight or BMI, and a small but statistically significant reduction in waist-to-hip ratio.
For scale, the Phase 3 TRIUMPH-1 trial of retatrutide reported mean weight changes of -17.6% to -25.0% over 80 weeks (treatment-regimen estimand). Those results belong to a different substance given by injection under medical supervision.
Berberine safety notes
The National Center for Complementary and Integrative Health reports that side effects of berberine in studies were mainly gastrointestinal, such as nausea, abdominal pain, bloating, constipation or diarrhea. It also states that berberine may interact with medicines, that it is likely to be unsafe for infants, and that it may be unsafe during pregnancy or breastfeeding. The GLP3-B sales page itself tells readers who are on medical treatment to ask a doctor or pharmacist first, "particularly for treatments related to diabetes or blood clotting", and flags the caffeine in guarana for people who are sensitive to stimulants.
What could not be verified
- Who makes it. None of the three seller pages names a manufacturer.
- The formula. The berberine amount differs between seller pages (100 mg or 150 mg).
- The ratings. The sales page shows a rating of 4.9 out of 5 from 1,528 reviews. The two shop listings display ratings of 5.0 and 4.8 out of 5, and the review tab on each read "Reviews (0)" when checked. Neither rating could be traced to published reviews.
- Any result. No published study of the product was found, and the sales page says it is "not a test, an independent review, or a press article".
GLP3-B, GLP3-R and retatrutide: how the labels differ
Several similar labels circulate online. They do not describe the same product.
| Label | What it is sold as | Is it the drug tested in the TRIUMPH trials? |
|---|---|---|
| GLP3-B | A berberine food-supplement capsule | No |
| GLP3-R, GLP-3 RT, GLP3 RT, "Reta" | Vials sold online as retatrutide, usually marked for research use only | Unverified. These products are not FDA-approved, and the FDA describes them as of unknown quality |
| Retatrutide (LY3437943) | Not sold. An investigational drug in Lilly's clinical trials | Yes |
None of these labels is a regulatory name. PubMed has no record with "GLP3-B", "GLP3-R" or "GLP-3 RT" in a title or abstract, and ClinicalTrials.gov lists no study under "GLP3-B" or "GLP3-R". The trials are registered under retatrutide, which returns 34 studies. The FDA's database of approved drugs contains no retatrutide product.
On the vials, the FDA states that it "has warned companies that have illegally sold unapproved drugs containing semaglutide, tirzepatide, retatrutide, survodutide or mazdutide that are falsely labeled 'for research purposes' or 'not for human consumption'", and it "urges consumers not to purchase these products which are of unknown quality and may be harmful to their health". It also states that retatrutide "cannot be used in compounding under federal law". See the black-market warning and what the trials reported on retatrutide safety.
How supplements are regulated
A supplement does not go through the testing a medicine does. In the United States, the FDA states that it "does NOT have the authority to approve dietary supplements for safety and effectiveness", and that "a product intended to treat, prevent, cure, or alleviate the symptoms of a disease is a drug". GLP3-B is marketed in the UK and across Europe, where its sellers likewise describe it as a food supplement and not a medicine. No regulatory review of GLP3-B and weight loss was found in the sources checked for this article, and its sellers do not present it as a medicine.
Related reading: what GLP3 (retatrutide) is, the retatrutide clinical trials, trial results by week and contraindications and trial exclusions.
Frequently asked questions
What is GLP3-B?
GLP3-B is a capsule sold online in the UK and across Europe. Its sellers describe it as a food supplement, not a medicine, taken by mouth once a day. Seller pages list berberine as the main ingredient, with guarana, inulin, L-glutamine, L-leucine, zinc and chromium.
Is GLP3-B the same as GLP3 or retatrutide?
No. GLP3 and GLP-3 are nicknames for retatrutide, an investigational drug given as a once-weekly injection in Eli Lilly's clinical trials. GLP3-B is a berberine supplement capsule. None of the three GLP3-B seller pages reviewed for this article mentions retatrutide.
Does GLP3-B contain a GLP-1 drug?
Not according to its sellers. The ingredient lists on the three seller pages reviewed contain berberine, guarana, inulin, two amino acids, zinc and chromium. None lists semaglutide, tirzepatide, retatrutide or any other GLP-1 medicine.
Does GLP3-B work for weight loss?
No clinical trial of GLP3-B was found on PubMed or ClinicalTrials.gov. One seller page states that the product does not guarantee weight loss or any specific result. For berberine itself, the U.S. National Center for Complementary and Integrative Health says the weight-loss evidence is not conclusive and that effects were seen mainly at doses above 1 gram a day, compared with the 100 mg to 150 mg listed for GLP3-B. That comparison is not a suggestion to take more than the labelled amount.
Is GLP3-B safe?
The product itself has not been tested in a published study. For berberine, the National Center for Complementary and Integrative Health reports mainly gastrointestinal side effects, notes that berberine may interact with medicines, and says it is likely unsafe for infants and may be unsafe during pregnancy or breastfeeding. The formula also contains guarana, a source of caffeine.
Is GLP3-B approved by the FDA?
No. Seller pages describe GLP3-B as a food supplement, and the FDA states that it does not have the authority to approve dietary supplements for safety and effectiveness. Retatrutide, the drug nicknamed GLP3, is not FDA-approved either.
What is the difference between GLP3-B and GLP3-R?
GLP3-B is a supplement capsule built around berberine. GLP3-R and GLP-3 RT are labels used by online sellers on vials sold as retatrutide for research use. The FDA has warned companies selling unapproved retatrutide labeled for research purposes and urges consumers not to buy these products.
Sources
- GLP3-B sales page at glp3-b.eu/uk/, which describes itself as an affiliate site and not the manufacturer. Reviewed November 11, 2026. Not linked, because this site does not link to sellers.
- Two UK online shop listings for GLP3-B. Reviewed November 11, 2026. Not named or linked, because this site does not link to sellers.
- National Center for Complementary and Integrative Health (NIH). Berberine and Weight Loss: What You Need To Know. Last updated November 2023.
- Asbaghi O, et al. The effect of berberine supplementation on obesity parameters, inflammation and liver function enzymes: A systematic review and meta-analysis of randomized controlled trials. Clin Nutr ESPEN. 2020;38:43-49. PMID 32690176.
- Elahi Vahed I, et al. The effect of berberine on obesity indices: a systematic review and meta-analysis. Int J Obes (Lond). 2026;50(1):53-73. PMID 41310257.
- Xiong P, et al. The effect of berberine supplementation on obesity indices: A dose-response meta-analysis and systematic review of randomized controlled trials. Complement Ther Clin Pract. 2020;39:101113. PMID 32379652.
- Amini MR, et al. Effects of berberine and barberry on anthropometric measures: A systematic review and meta-analysis of randomized controlled trials. Complement Ther Med. 2020;49:102337. PMID 32147051.
- Jastreboff AM, et al. Retatrutide, a Triple Hormone Receptor Agonist, for Treatment of Obesity (TRIUMPH-1). N Engl J Med. 2026;395(18):1781-1793. PMID 42814954.
- Eli Lilly and Company. TRIUMPH-1 topline press release. May 21, 2026.
- PubMed title and abstract searches for "GLP3-B", "GLP-3B", "GLP3-R" and "GLP-3 RT". Run November 11, 2026. No records for any of the four.
- ClinicalTrials.gov searches for "GLP3-B" and "GLP3-R" (no studies) and for retatrutide (34 studies). Run November 11, 2026.
- U.S. Food and Drug Administration. Drugs@FDA, searched through the openFDA API on November 11, 2026. No approved product contains retatrutide.
- U.S. Food and Drug Administration. FDA's Concerns with Unapproved GLP-1 Drugs Used for Weight Loss. Content current as of October 1, 2026.
- U.S. Food and Drug Administration. FDA 101: Dietary Supplements. Content current as of June 2, 2022.
Written and maintained by the GLP3 Weight Loss Editorial Team. Last updated November 11, 2026. Educational content only, not medical advice. GLP3 Weight Loss is not a healthcare provider and does not prescribe, dispense or sell retatrutide for human use.