White mulberry leaf

What it is

White mulberry leaf is the leaf of Morus alba, the tree traditionally grown to feed silkworms, taken as a tea, a powder or a standardised extract. Its leaves have been used in Asia for a range of complaints including disordered blood sugar. Commercial extracts are commonly standardised to their content of the iminosugar 1-deoxynojirimycin (DNJ) - one randomised trial used an extract standardised to 5% DNJ.

What the research says

The evidence that stands up best is short-term and about the meal, not the disease: a 2022 systematic review of randomised trials concluded that Morus alba can reduce post-prandial glucose and insulin, while stating in the same breath that it is insufficient to conclude it is an effective intervention for lowering blood glucose. A three-month randomised pilot in people with type 2 diabetes reproduced that pattern: post-meal readings improved, but HbA1c did not differ from placebo. That pilot also recorded a 15% rise in serum creatinine in the mulberry group, which is the single hardest safety signal in the human data. A separate four-week randomised safety trial of a mulberry-leaf beverage found no excess adverse events.

Evidence grade: Limited evidence.

What goes wrong

The same trial recorded a significant 15% rise in serum creatinine in the mulberry leaf extract group compared with both its own baseline and placebo. (Source 1)

• Randomized trial, Low certainty.
• Size: 17 completers.
• Who: adults with type 2 diabetes on oral therapy.
• How long: 3 months.
• Result: 15% increase in serum creatinine (p < 0.05 versus baseline and versus placebo); no significant effect on other safety markers or on hypoglycaemia.
• Funding: not stated in the abstract.

A significant 15% increase occurred in serum creatinine when the MLE group was compared to baseline or placebo (p < 0.05 for both).

What the evidence supports

A 2022 systematic review and meta-analysis of randomised trials found that Morus alba reduces post-prandial glucose and insulin levels. (Source 2)

• Systematic review, Low certainty.
• Size: randomised controlled trials identified in PubMed, EMBASE and four Korean databases (number not stated in the abstract)
• Who: people using Morus alba for blood sugar management, including patients with diabetes mellitus.
• How long: varied; not stated in the abstract.
• Result: direction of effect reported for post-prandial glucose and insulin; no pooled numeric estimate given in the abstract.
• Funding: not stated.

Our results showed that Morus alba can reduce postprandial glucose and insulin levels.

In a three-month randomised, double-blind, placebo-controlled pilot in people with type 2 diabetes already on oral medication, post-prandial self-monitored glucose fell in the mulberry group relative to placebo. (Source 1)

• Randomized trial, Low certainty.
• Size: 24 patients enrolled, 17 completed.
• Who: adults with type 2 diabetes on single or combination oral therapy with stable HbA1c.
• How long: 2-week placebo run-in then 3 months of randomised treatment.
• Result: post-prandial SMBG fell 16.1% vs baseline (p < 0.05) and 18.2% vs placebo (p < 0.05)
• Funding: not stated in the abstract.

This improvement in post-prandial SMBG persisted when compared to placebo (18.2%; p < 0.05).

A four-week randomised, double-blind, placebo-controlled safety trial of a green tea containing mulberry leaf extract in healthy adults found no adverse reactions and no difference in adverse event rates between groups. (Source 3)

• Randomized trial, Low certainty.
• Size: 48 participants.
• Who: healthy adults.
• How long: 4 weeks, three servings daily.
• Result: no adverse reactions observed; no between-group difference in incidence of adverse events.
• Funding: not stated in the abstract (beverage safety study, likely manufacturer-linked; a reviewer should check the declaration)

No adverse reactions were observed over the 4 weeks trial, and no difference in the incidence of adverse events between the groups.

What the evidence does not support

The same systematic review states explicitly that the evidence is insufficient to conclude Morus alba is an effective intervention for lowering blood glucose. (Source 2)

• Systematic review, Low certainty.
• Size: as above.
• Who: as above.
• How long: as above.
• Result: no reliable pooled effect on blood glucose lowering; authors call for more rigorous studies.
• Funding: not stated.

However, it is insufficient to conclude that Morus alba is an effective intervention for lowering blood glucose levels.

In that same pilot trial, mulberry leaf extract did not lower HbA1c compared with placebo. (Source 1)

• Randomized trial, Low certainty.
• Size: 24 enrolled, 17 completed.
• Who: adults with type 2 diabetes on oral therapy.
• How long: 3 months.
• Result: HbA1c fell from 7.30% to 6.94% within the MLE group but did not reach significance (p = 0.079), and there was no difference versus placebo; no significant effect on weight, fasting glucose or blood pressure.
• Funding: not stated in the abstract.

A1C decreased from 7.30% at baseline to 6.94% in the MLE group but did not reach statistical significance (p = 0.079). There was no difference in A1C between MLE and placebo.

Where the evidence is mixed

A 12-week randomised placebo-controlled trial of a fixed-dose combination containing white mulberry leaf extract improved body composition and insulin sensitivity, but the design cannot attribute any of that to the mulberry component. (Source 4)

• Randomized trial, Low certainty.
• Size: 93 randomised (46 active, 47 placebo)
• Who: Greek adults with obesity and no diagnosed chronic disease.
• How long: 12 weeks.
• Result: BMI -1.24 kg/m2 (95% CI -2.15 to -0.33); total body fat mass -2.35 kg (95% CI -4.12 to -0.58); visceral fat rating -0.92 (95% CI -1.74 to -0.10); insulin sensitivity 28% greater improvement (geometric mean ratio 1.28, 95% CI 1.14 to 1.44)
• Funding: internal research grant (per the article's funding statement)

Because no single-agent arms were included, individual component contributions and synergy remain undetermined; confirmatory trials using direct metabolic and imaging methods are warranted.

Where the research disagrees

Whether mulberry leaf is safe for the kidneys

• Riche and colleagues, Complementary Therapies in Medicine 2017, randomised, double-blind, placebo-controlled pilot trial, 17 completers, 3 months: A significant 15% increase occurred in serum creatinine when the MLE group was compared to baseline or placebo (p < 0.05 for both). (Source 1)
• Safety evaluation of a beverage containing mulberry leaf extract, Bioscience, Biotechnology, and Biochemistry 2022, randomised, double-blind, placebo-controlled parallel-group safety trial, 48 healthy adults, 4 weeks: No adverse reactions were observed over the 4 weeks trial, and no difference in the incidence of adverse events between the groups. (Source 3)

How much

• Reference intake: No reference intake exists. White mulberry leaf is a botanical, not an essential nutrient; the systematic review describes it as something used for blood sugar management rather than as a dietary requirement. (Source 2)
• Upper limit: No tolerable upper intake level or acceptable daily intake has been set by any body we could reach. The nearest formal safety data point is a four-week randomised trial concluding that 550 mg of mulberry leaf extract three times a day is safe for healthy adults. (Source 3)
• Studied: 1000 mg of standardised mulberry leaf extract three times daily with meals for 3 months in adults with type 2 diabetes. (Source 1)
• Studied: 550 mg of mulberry leaf extract in 500 mL of green tea, three times a day for 4 weeks, in 48 healthy adults. (Source 3)
• Studied: 400 mg of white mulberry leaf extract standardised to 5% 1-deoxynojirimycin daily, given in two doses before main meals as part of a combination product, for 12 weeks. (Source 5)

A common belief, and what the research shows

The belief: White mulberry leaf lowers blood sugar, so it treats diabetes.

What the research shows: The randomised evidence is about the hours after a meal, not about long-term control. The 2022 systematic review found that "Morus alba can reduce postprandial glucose and insulin levels" but immediately added: "However, it is insufficient to conclude that Morus alba is an effective intervention for lowering blood glucose levels." In the longest placebo-controlled trial we could read, "There was no difference in A1C between MLE and placebo."

Questions and answers

What is it?

White mulberry leaf is the leaf of the Morus alba tree, taken as a tea, dried powder or standardised extract. It has a long record of traditional use in Asia, including for blood sugar problems. Modern supplements are usually standardised to the iminosugar 1-deoxynojirimycin. (Source 1)

What does it do in the body?

Its studied action is on the digestion and absorption of carbohydrate, so that the rise in blood glucose after a meal is blunted. That is the effect randomised trials have looked at and the one the systematic review found. Effects on longer-term measures such as HbA1c have not been shown. (Source 3)

Is it good or bad for you?

Short-term it appears well tolerated: a four-week randomised safety trial in healthy adults found no excess adverse events. But the one three-month placebo-controlled trial in people with type 2 diabetes recorded a significant rise in serum creatinine, a kidney marker, in the mulberry group. Benefit is confined to post-meal glucose, and long-term safety has not been established. (Source 1)

How do you get more of it?

In trials people took it as a capsule or extract with meals, as a green tea containing the extract, or as one component of a combination supplement. Products differ a great deal; the most explicit standardisation we found in a trial was an extract standardised to 5% 1-deoxynojirimycin. (Source 5)

If it is harmful, what reduces it?

Exposure ends when the product is stopped - mulberry leaf is not stored or produced by the body. In the four-week randomised safety trial no adverse reactions were seen at all, and in the three-month trial the reported side-effect profile was otherwise unremarkable apart from the creatinine change. (Source 1)

Why might someone be low in it or missing it?

This does not apply. White mulberry leaf is not a nutrient the body requires or manufactures, so there is no deficiency. A person has none unless they eat or drink a mulberry leaf preparation; it is described in the literature as something used for blood sugar management, not as a dietary requirement. (Source 2)

Which whole foods contain it or feed it?

The leaf itself is the source. It is consumed as mulberry leaf tea or as leaf powder, and in trials as a concentrated leaf extract added to a beverage or capsule. Mulberry fruit is a different part of the same plant and has been studied separately; the trials described here used leaf. (Source 3)

What happens if you do not have it?

Nothing happens if you never take it. There is no deficiency syndrome, and the systematic review that pooled the randomised trials says it cannot even be concluded that mulberry leaf is an effective way of lowering blood glucose, so nothing established is being missed. (Source 2)

How can you test for it?

There is no validated test for mulberry leaf or its constituents in a person. What trials actually measured was the effect: HbA1c and self-monitored blood glucose readings before and after meals. Those measure glucose control, not whether mulberry is present or working, and in the trial they moved only for post-meal readings. (Source 1)

We searched: Searched PubMed, Crossref and journal pages for 1-deoxynojirimycin biomarker, pharmacokinetic and assay studies in humans, and for validated Morus alba exposure tests; found only outcome measurements (HbA1c, self-monitored glucose) in the trials.

References

1. Complementary Therapies in Medicine. Impact of mulberry leaf extract on type 2 diabetes (Mul-DM): A randomized, placebo-controlled pilot study. 2017. PMID 28619294, DOI 10.1016/j.ctim.2017.04.006. Read the source
2. Evidence-Based Complementary and Alternative Medicine. Morus alba L. for Blood Sugar Management: A Systematic Review and Meta-Analysis. 2022. PMID 35656468, DOI 10.1155/2022/9282154. Read the source
3. Bioscience, Biotechnology, and Biochemistry. Safety evaluation of a beverage containing mulberry leaf extract. 2022. PMID 35089999, DOI 10.1093/bbb/zbac011. Read the source
4. Nutrients. Effects of Berberine, White Mulberry Leaf Extract and Chromium Picolinate on Body Composition and Insulin Resistance in Adults with Obesity: A Randomized Controlled Trial (Results and Conclusions). 2026. DOI 10.3390/nu18172801. Read the source
5. Nutrients. Effects of Berberine, White Mulberry Leaf Extract and Chromium Picolinate on Body Composition and Insulin Resistance in Adults with Obesity: A Randomized Controlled Trial (Objectives and Methods). 2026. DOI 10.3390/nu18172801. Read the source