Berberis vulgaris / Coptis chinensis (alkaloid) · supplement
Evidence tier: moderate
Lowers blood glucose, improves insulin sensitivity, and reduces LDL cholesterol, one of the most evidence backed plant compounds for blood sugar management
Berberine works mainly on the metabolic and digestive systems. The leading explanation is activation of AMPK, the cell's fuel gauge, which reduces sugar output from the liver and helps muscle take up glucose. It also modulates drug handling enzymes (CYP3A4, CYP2D6, CYP2C9) and transporters (P-glycoprotein, OCT1, OCT2, MATE1), which is why it interacts with so many medicines, metformin included (PMID 42653808, narrative review).
Moderate for blood sugar, and that is the strongest thing berberine has. A head to head trial found berberine 0.5 g three times daily had a glucose lowering effect similar to metformin, with transient digestive effects in about a third of people (PMID 18442638). Pooled reviews confirm a replicated but modest effect on HbA1c and fasting glucose (PMIDs 34956436, 36467075, 38016844), and the newest pooling calls it adjunctive rather than primary (PMID 42213651). Cholesterol and triglycerides are limited (PMID 35988871). For SIBO, candida and rosacea no supporting systematic review was found. The safety story is the interaction surface, not the liver: LiverTox finds no liver injury signal, but berberine inhibits CYP3A4, CYP2D6 and CYP2C9 at ordinary doses (PMID 21870106), acts on P-glycoprotein and on the transporters metformin depends on (OCT1, OCT2, MATE1) (PMID 42653808), raises cyclosporine levels in transplant patients (PMID 16133554), and must be avoided in pregnancy, while breastfeeding and in newborns because it displaces bilirubin (PMID 8513024).
Trials commonly used 0.5 g (500 mg) three times daily with meals (PMID 18442638). The human enzyme blocking study used 300 mg three times daily, inside the ordinary supplement range (PMID 21870106), so interaction risk is present at label doses.
Take with food and build up gradually; digestive effects affected about a third of people in a trial and were transient [PMID 18442638]. Anyone on metformin, other blood sugar medicines, cyclosporine or any prescription medicine should talk to their doctor or pharmacist first, and monitor blood sugar if on glucose lowering treatment [PMIDs 39943692, 21870106].
Onset: ~14 days
GI side effects (constipation, nausea, diarrhoea) common at initiation, titrate slowly and take with food. Significant hypoglycaemia risk when combined with diabetes medications. CYP3A4/P-gp inhibition causes multiple drug interactions. Avoid in pregnancy (uterotonic). Avoid with cyclosporine without prescriber knowledge.
Pregnancy: avoid
Breastfeeding: avoid
Used in Ayurvedic and Traditional Chinese Medicine for thousands of years for digestive complaints, diarrhoea, and infections. Extracted from plants including barberry, goldenseal, and Oregon grape.
Active compounds: berberine, berberine hydrochloride
Remedies using Berberine · Browse by body system · Check it against what you take
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.