Supplement analysis backed by scientific evidence · PT · ES · DE · FR

← All supplements
Moderate evidenceHeart & metabolic

Mulberry Leaf

Mulberry leaf extract contains 1-deoxynojirimycin (DNJ), a genuine alpha-glucosidase inhibitor that blunts post-meal blood glucose spikes in controlled trials. The effect is real and mechanistically clear, but it is a meal-timing tool for postprandial glucose, not a treatment for diabetes.

View on iHerb Ships to 180+ countries · welcome discount for new customers

What the science says

  • Blunts post-meal glucose and insulin spikes Moderate evidence

    A double-blind randomized crossover trial of a standardized mulberry leaf extract (Reducose) found dose-dependent reductions in post-meal glucose and insulin after a complex meal, with meaningful effects from 250 mg and clear responses at 500-1,000 mg taken with the meal. The mechanism is the same as prescription acarbose — DNJ competitively inhibits intestinal alpha-glucosidase, slowing starch and sucrose digestion. The extract must be taken with or just before the carbohydrate to work.

  • Small but consistent effects on fasting glucose and HbA1c in meta-analysis Moderate evidence

    A systematic review and meta-analysis of mulberry leaf and mulberry leaf extract on glycemic traits pooled randomized trials and found reductions in postprandial glucose along with modest improvements in fasting glucose and HbA1c. Effect sizes on HbA1c are small (typically a few tenths of a percentage point), trials are short (4-12 weeks), and extract standardization varies widely — so this is a supportive adjunct, not a substitute for glucose-lowering medication.

  • Cardiometabolic claims beyond glucose are weaker Limited evidence

    A meta-analysis of mulberry consumption on cardiometabolic risk factors found some improvement in lipid measures, but effects on blood pressure and body weight were inconsistent and driven by few small trials. Claims that mulberry leaf is a weight-loss agent or a "carb blocker" that lets you eat freely are not supported — the calorie sparing from partial starch inhibition is modest.

Dosage & safety

Studied doseTrials of standardized extract use 250-1,000 mg taken immediately before a carbohydrate-containing meal, with 250 mg (delivering roughly 5 mg DNJ) as the common minimum effective dose and 500-1,000 mg for larger effects. Whole leaf powder or tea is dosed at 3-12 g/day in Asian trials. Look for DNJ standardization on the label — unstandardized leaf powder can contain a fraction of the DNJ in a concentrated extract. Timing is not optional: taken between meals it does nothing.
SafetySide effects mirror acarbose and come from undigested carbohydrate fermenting in the colon: bloating, flatulence, abdominal cramping and loose stools, most common at higher doses and with high-carbohydrate meals. Starting low and titrating reduces this. Real interaction risk with insulin and sulfonylureas — additive glucose lowering can cause hypoglycemia, and note that if hypoglycemia occurs while on an alpha-glucosidase inhibitor, table sugar works poorly and glucose tablets should be used instead. Avoid combining with prescription acarbose or miglitol. Insufficient data in pregnancy and breastfeeding. Mulberry leaf is a food in several Asian cuisines with a long safety record at culinary doses.

How to take it

TimingTake it immediately before a carbohydrate-containing meal — between meals it does nothing.
With food?With the first bites of the meal, since it works on the carbohydrate in the gut as you eat it.
Worth knowingIf you are on an alpha-glucosidase inhibitor and go hypoglycemic, table sugar works poorly — carry glucose tablets instead.

Interactions

With medications

  • insulin and sulfonylureas

    Additive blood-glucose lowering can push you into hypoglycemia. monitor glucose and adjust doses only with your prescriber

  • acarbose and miglitol

    Same alpha-glucosidase-inhibiting mechanism, so gastrointestinal side effects stack without added benefit. do not combine

With other supplements

  • other carbohydrate-blocking or glucose-lowering supplements (salacia, banaba, berberine, white kidney bean)

    Additive glucose lowering and additive gas, bloating and loose stools. use one at a time rather than stacking

Well-established interactions only — this is not a complete list. Always tell your doctor and pharmacist what you take.

Frequently asked questions

Does mulberry leaf lower blood sugar?

Mulberry leaf extract has moderate evidence for blunting post-meal glucose and insulin spikes: its DNJ inhibits carbohydrate digestion the same way prescription acarbose does. Effects on HbA1c are small, typically a few tenths of a percentage point, so mulberry leaf is an adjunct, not a treatment for diabetes.

When should I take mulberry leaf extract?

Take mulberry leaf extract immediately before or with the first bites of a carbohydrate-containing meal; taken between meals it does nothing. Trials used 250-1,000 mg of standardized extract, with 250 mg as the common minimum effective dose.

Is mulberry leaf a carb blocker for weight loss?

Mulberry leaf is not a weight-loss agent or a carb blocker that lets you eat freely (limited evidence): effects on body weight were inconsistent in meta-analysis, and the calories spared from partial starch inhibition are modest.

What are the side effects of mulberry leaf?

Mulberry leaf commonly causes bloating, flatulence, cramping and loose stools, because undigested carbohydrate ferments in the colon; starting low reduces this. With insulin or sulfonylureas it can cause hypoglycemia, and if that happens, use glucose tablets rather than table sugar.

Scientific references

Where to buy

Swanson Vitamins, Mulberry Leaf Extract, 500 mg, 60 Capsules

View on iHerb

Ships to 180+ countries · welcome discount for new customers

Referral link — this site may earn a commission on purchases.

Related in Heart & metabolic