White mulberry leaf (Morus alba)

Tier 3 — weak evidence · Blood sugar · Alpha-glucosidase inhibitor

Contains 1-deoxynojirimycin (DNJ), a natural alpha-glucosidase inhibitor that works similarly to the prescription diabetes drug acarbose. Small trials show it significantly reduces post-meal blood sugar spikes when taken before carbohydrate-rich meals. The mechanism is well characterised. May cause gas and bloating as undigested carbs ferment in the colon, similar to acarbose.

Dose: 1,000–3,000 mg/day leaf extract before carbohydrate meals; may cause gas similar to acarbose