Mulberry Leaf
Morus alba
The leaf of the white mulberry tree (the silkworm's food) contains 1-deoxynojirimycin, a natural alpha-glucosidase inhibitor that blunts blood sugar spikes after carbohydrate-rich meals, supported by several randomized trials.
At a Glance
- Best known for
- Reduces post-meal blood glucose and insulin spikes, May improve HbA1c with regular use, Supports healthy lipid levels (preliminary)
- Evidence
- Moderate
- Typical dose
- 250 mg standardized extract (≈12 mg DNJ) immediately before a carbohydrate meal
- Type
- Herb
What is Mulberry Leaf?
The white mulberry (Morus alba) is a fast-growing tree native to China, cultivated for millennia as the sole food of the silkworm. Its leaves have been used in Traditional Chinese Medicine (sang ye) for fever, cough, and 'wasting-thirst' (diabetes), and mulberry leaf tea is a traditional drink in China, Japan, and Korea. In the 1970s Japanese researchers identified 1-deoxynojirimycin (DNJ), a sugar-mimicking alkaloid that inhibits the enzymes that break down carbohydrates, giving the leaf a mechanism similar to the diabetes drug acarbose. Standardized extracts are now widely sold for blood sugar management.
Known Health Benefits
How It Works
DNJ and related iminosugars are structural mimics of glucose that competitively inhibit alpha-glucosidase enzymes (sucrase, maltase, and others) on the brush border of the small intestine. This slows the breakdown of sucrose and starch into absorbable glucose, flattening the post-meal rise in blood glucose and insulin and shifting some carbohydrate digestion to the colon. Mulberry leaf also inhibits pancreatic alpha-amylase and may reduce glucose transport across the gut wall via SGLT1. Flavonoids such as quercetin and isoquercitrin add antioxidant and anti-inflammatory activity and may improve insulin sensitivity. Animal studies show improved lipid profiles and reduced liver fat, possibly through AMPK activation. Because carbohydrates reach the colon, fermentation can also increase short-chain fatty acid production.
What Research Says
Mulberry leaf has a relatively consistent set of small randomized trials. A 2007 study in Diabetes Care found 1 g of mulberry leaf extract reduced the glucose rise after 75 g sucrose in both type 2 diabetic and healthy subjects, with increased breath hydrogen confirming carbohydrate reaching the colon. A 2017 UK randomized, double-blind crossover trial of 37 healthy adults found a standardized extract (Reducose, 250 mg providing 12.5 mg DNJ) reduced peak glucose by about 40% and insulin by about 40% after a maltodextrin load. A 2021 trial in 38 adults confirmed dose-dependent reductions in glucose and insulin area-under-curve. Longer studies are fewer: a 2007 Thai trial found 3 months of mulberry leaf tablets modestly reduced fasting glucose and HbA1c, and a 2022 systematic review and meta-analysis of randomized trials reported significant reductions in post-prandial glucose and insulin, with more modest effects on fasting glucose and lipids. Trials are small and mostly short, but the acute effect on post-meal glucose is well replicated, justifying a moderate rating for that outcome.
Active Compounds
1-Deoxynojirimycin (DNJ) and related iminosugars (fagomine), flavonoids (quercetin, rutin, isoquercitrin, kaempferol), chlorogenic acid, GABA, polysaccharides
Forms & Bioavailability
DNJ acts locally in the small intestine, so it must be taken at the start of a carbohydrate-containing meal to be effective; taking it hours before or after eating does little. DNJ itself is absorbed (bioavailability roughly 20%) and excreted in urine within hours, and systemic levels are not required for the enzyme-inhibiting effect. DNJ content varies enormously between products and growing conditions, from under 0.1% in some leaf powders to 5% in enriched extracts, so standardized products are strongly preferred. Flavonoid absorption is moderate.
Dosage Guidance
| Use Case | Dosage |
|---|---|
| Post-meal glucose control | 250 mg standardized extract (≈12 mg DNJ) immediately before a carbohydrate meal |
| Daily blood sugar support | 500 mg extract (3–6 mg DNJ) with each main meal |
| Leaf tea | 2–3 g dried leaf steeped 5–10 min with meals |
| Leaf powder (food) | 1–3 g daily mixed into food |
| Lipid support | 1,000 mg extract daily |
Always consult a healthcare provider for personalized dosing.
Natural Food Sources
- Mulberry leaf tea (traditional in East Asia)
- Mulberry leaf powder (added to noodles, rice, and smoothies in Japan)
- Young mulberry leaves (cooked as a vegetable in some regions)
- Mulberry fruit (contains little DNJ; different nutrient profile)
Potential Side Effects
Bloating, gas, loose stools from undigested carbohydrate reaching the colon (similar to acarbose); possible hypoglycemia with diabetes drugs; rare allergic reaction
Who Should Avoid It
- Insulin or sulfonylurea therapy without monitoring (hypoglycemia)
- Acarbose or miglitol therapy (duplicative mechanism; additive GI effects)
- Pregnancy and breastfeeding (no safety data)
- Inflammatory bowel disease or severe IBS (carbohydrate malabsorption worsens symptoms)
- Scheduled surgery (stop 2 weeks before)
Pregnancy & Lactation
Not recommended in supplement doses during pregnancy or breastfeeding owing to a lack of safety data and effects on glucose handling. Mulberry leaf tea in modest culinary amounts has long traditional use but has not been formally studied in pregnancy.
Known Drug Interactions
Additive glucose lowering with insulin and oral diabetes drugs; may compound GI effects of acarbose/miglitol; theoretical interaction with lipid-lowering drugs; may slow absorption of sugars in oral rehydration or hypoglycemia treatment
Evidence Classification
Supported by cohort studies, case-control studies, or multiple observational studies with consistent findings.
Frequently Asked Questions
How is mulberry leaf different from the diabetes drug acarbose?
They share the same mechanism: both inhibit the intestinal enzymes that break down carbohydrates. Acarbose is a single purified compound with strong trial evidence and a known dose; mulberry leaf delivers a lower, more variable dose of DNJ along with flavonoids and other compounds. Mulberry generally causes less gas and bloating, probably because its effect is milder. They should not be combined without medical advice.
When should I take it?
At the start of a meal containing starch or sugar. DNJ works by blocking enzymes in the gut as food arrives, so timing matters more than for most supplements. Taking it with a protein-only or fat-only meal has no purpose.
Does mulberry fruit do the same thing?
No. The fruit is a tasty source of anthocyanins and vitamin C but contains very little DNJ. The leaf is the part with the glucose-blocking activity.
Will it help me lose weight?
By flattening post-meal glucose and insulin and diverting some carbohydrate from absorption, mulberry leaf could theoretically support weight management, and a few small studies report modest reductions in weight or waist circumference. The effect is small; it is not a substitute for dietary change.
References
- Mulberry-extract improves glucose tolerance and decreases insulin concentrations in normoglycaemic adults: Results of a randomised double-blind placebo-controlled study. Lown M, Fuller R, Lightowler H, et al.. PLoS One (2017)View study
- Influence of mulberry leaf extract on the blood glucose and breath hydrogen response to ingestion of 75 g sucrose by type 2 diabetic and control subjects. Mudra M, Ercan-Fang N, Zhong L, Furne J, Levitt M. Diabetes Care (2007)View study
- Mulberry leaves and their potential effects against cardiometabolic risks: a review of chemical compositions, biological properties and clinical efficacy. Thaipitakwong T, Numhom S, Aramwit P. Pharm Biol (2018)
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This entry is for educational purposes only. It is not medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any supplement regimen, especially if you take medications or have health conditions.