Berberine, a compound found in plants like barberry, has been nicknamed “nature’s metformin” online. That’s a catchy line, but it overstates the case.

Meta-analyses of clinical trials suggest berberine can modestly lower fasting blood glucose and HbA1c in people with type 2 diabetes, and may improve cholesterol levels. However, most trials are small, short and conducted in China, which limits how confidently the results apply elsewhere. We lack large, long-term studies on outcomes that matter most, like heart attacks or complications.

Digestive side effects are the most common problem, including cramping, diarrhoea and constipation. Berberine can also interact with other medicines. It may add to the effect of blood-sugar-lowering drugs (raising the risk of hypoglycaemia) and can affect how the liver processes some medications, including cyclosporine.

It shouldn’t be used during pregnancy or breastfeeding, and it is not a substitute for prescribed diabetes treatment. If you have diabetes or prediabetes, talk to your doctor before trying it.

Bottom line: Berberine shows promise, but it’s no replacement for proven approaches such as diet, movement, weight management and prescribed medication when needed.