Jamun

Also called Syzygium cumini, Jambolan, Java plum, Black plum, Eugenia jambolana, Jamun seed powder.

Best grade C across 5 graded outcomes Botanical Last checked

The short answer

From 8 sources

Jamun is a traditional blood-sugar remedy, but trials of jamun alone are small and mostly null. Leaf tea did not lower glucose in 27 people with type 2 diabetes over 28 days or in 30 healthy volunteers. A 2026 meta-analysis pooling jamun with related plants found a modest fasting glucose drop with very uncertain evidence and no HbA1c change.

Every graded outcome on this page

5 rows · line = participants
  1. Grade CGlycemic control in type 2 diabetes or prediabetesBlood sugarn 776
  2. Grade DBlood glucose in type 2 diabetes (herb blend)Blood sugarn 60
  3. Grade DBlood lipids in high cholesterolBlood lipidsn 60
  4. Grade DGlucose tolerance in healthy volunteersBlood sugarn 30
  5. Grade DFasting blood glucose in type 2 diabetesBlood sugarn 27
  6. 2 more graded outcomes, in the evidence chapter

Key facts

Leaf tea in diabetes
No change in fasting glucose over 28 days vs placebo in 27 people with type 2 diabetes; glyburide did lower it1
Healthy volunteers
Leaf tea had no effect on a glucose tolerance test in 30 young adults2
Pooled trials
13 trials (802 people) of jamun and related Myrtaceae plants: fasting glucose -14.4 mg/dL; HbA1c and post-meal glucose not significantly changed4
Certainty
The meta-analysis rated the evidence low to very low, with very high heterogeneity and no low-risk-of-bias trials4
Blood lipids
No significant pooled lipid change in the 2026 meta-analysis; one small 2026 study of 1,000 mg/day for 3 months reported within-group falls in cholesterol and triglycerides48

What it is

Jamun (Syzygium cumini) is a tropical tree whose fruit, seeds and leaves are used in traditional medicine for blood sugar.

How it works

Proposed

Proposed from laboratory work: a jamun pomace extract inhibited the starch-digesting enzyme alpha-amylase in vitro. Rat studies of leaf and seed teas found no glucose-lowering effect.56

Forms, side by side

2 forms named in our sources. The rest show what our data holds, and say plainly where it holds nothing yet.

Jamun forms compared

2 forms
Jamun forms compared: 2 forms by 3 attributes. Empty cells are labelled No data yet, or Not graded in the evidence row.
2 formsLeaf teaSeed powder (often in blends)
Absorption in peopleNo human absorption data.1No human absorption data.3
GI toleranceKidney and liver markers did not differ from placebo over 28 days.1The 3-month blend study abstract reports no problems; lab safety markers were not significantly changed across pooled trials.34
Studied forBlood sugar (null in two RCTs)Blood sugar (blends)
  1. Jamun leaf tea
    Absorption in people
    No human absorption data.1
    GI tolerance
    Kidney and liver markers did not differ from placebo over 28 days.1
    Studied for
    Blood sugar (null in two RCTs)
  2. Jamun seed powder (often in blends)
    Absorption in people
    No human absorption data.3
    GI tolerance
    The 3-month blend study abstract reports no problems; lab safety markers were not significantly changed across pooled trials.34
    Studied for
    Blood sugar (blends)
Every cell holds data from a cited page; citation numbers link to the page that holds them.Scroll the table for every column

What the human research says

Human trials only, one row per outcome. The form line shows what each trial actually tested. Grades follow our evidence-grading policy.

Trial map

5 graded outcomes, largest study first

5 graded outcomes: 1 improved, 2 mixed, 2 no effect. The largest, a 2026 meta-analysis of 776 people on glycemic control in type 2 diabetes or prediabetes, found mixed results.

3. Blood glucose in type 2 diabetes (herb blend): improved, 60 people3
1. Glycemic control in type 2 diabetes or prediabetes: mixed, 776 people12. Blood lipids in high cholesterol: mixed, 60 people2
4. Glucose tolerance in healthy volunteers: no effect, 30 people45. Fasting blood glucose in type 2 diabetes: no effect, 27 people5

1Glycemic control in type 2 diabetes or prediabetes

Mixed · Grade C · Meta-analysis, 776 people, 2026

Adults with type 2 diabetes or prediabetes in 13 RCTs

Dose, result and source
Every graded outcome on this page, largest study first
OutcomeFoundPeopleStudyWho was studied
Glycemic control in type 2 diabetes or prediabetesMixed776Grade C · Meta-analysis, 2026Adults with type 2 diabetes or prediabetes in 13 RCTs
Blood lipids in high cholesterolMixed60Grade D · Open-label trial, 2026Adults with high blood lipids in four groups of 15: jamun, ashwagandha, both, or atorvastatin 10 mg
Blood glucose in type 2 diabetes (herb blend)Improved60Grade D · Open-label trial, 2005Indian men with non-insulin-dependent diabetes
Glucose tolerance in healthy volunteersNo effect30Grade D · RCT, 2000Non-diabetic young volunteers in Porto Alegre, Brazil
Fasting blood glucose in type 2 diabetesNo effect27Grade D · RCT, 2006Brazilian adults with type 2 diabetes
Each circle is one graded outcome on this page, numbered from the largest study down, and placed by how many people it studied (log scale). It shows who was studied and what was found, not advice about your dose.

Every graded row

5 rows

Showing 5 of 5 outcomes. Human trials only.

Grade CGlycemic control in type 2 diabetes or prediabetesBlood sugarModest fasting glucose drop, low certaintyMeta-analysis · 13 studies
n 776 · 2026

Mixed Fasting glucose fell by 14.4 mg/dL (95% CI -23.1 to -5.7), but post-meal glucose and HbA1c did not change significantly; heterogeneity was extreme (I2 about 98-99%).

Design
Meta-analysis, 13 studies, n = 776, 2026
Population
Adults with type 2 diabetes or prediabetes in 13 RCTs
Form
Syzygium cumini and related Myrtaceae preparations
Dose
Various plant parts and formulations
Duration
Mostly short trials
Source
Reference 4 · PubMed 42450449 (opens PubMed)
Grade DBlood glucose in type 2 diabetes (herb blend)Blood sugarLower glucose (uncontrolled blend)Open-label trial
n 60 · 2005

Improved Fasting and post-meal glucose fell from baseline, and fewer men needed oral diabetes drugs.

Design
Open-label trial, n = 60, 2005
Population
Indian men with non-insulin-dependent diabetes
Form
Powdered blend of bitter gourd, jamun seed and fenugreek seed (capsules or biscuits)
Dose
1 g a day for 6 weeks, then 2 g a day
Duration
3 months
Source
Reference 3 · PubMed 16379570 (opens PubMed)
Grade DBlood lipids in high cholesterolBlood lipidsWithin-group falls onlyOpen-label trial
n 60 · 2026

Mixed In the jamun group, total cholesterol, triglycerides and systolic blood pressure fell from baseline; the abstract reports no comparison with the atorvastatin group. The 2026 meta-analysis found no significant pooled effect on lipids.

Design
Open-label trial, n = 60, 2026
Population
Adults with high blood lipids in four groups of 15: jamun, ashwagandha, both, or atorvastatin 10 mg
Form
Syzygium cumini (preparation not stated in the abstract)
Dose
500 mg twice daily (1,000 mg/day)
Duration
3 months
Source
Reference 8 · PubMed 42170977 (opens PubMed)
Grade DGlucose tolerance in healthy volunteersBlood sugarNo effectRCT
n 30 · 2000

No effect Jamun leaf tea had no antihyperglycemic effect on the glucose tolerance test.

Design
RCT, n = 30, 2000
Population
Non-diabetic young volunteers in Porto Alegre, Brazil
Form
Jamun leaf tea vs placebo
Dose
Leaf tea (preparation in the paper)
Duration
Before a glucose tolerance test
Source
Reference 2 · PubMed 10904184 (opens PubMed)
Grade DFasting blood glucose in type 2 diabetesBlood sugarNo glucose loweringRCT
n 27 · 2006

No effect Fasting glucose fell with glyburide but did not change with jamun tea or placebo; lipids, kidney and liver markers did not differ between groups.

Design
RCT, n = 27, 2006
Population
Brazilian adults with type 2 diabetes
Form
Jamun leaf tea plus placebo tablets vs placebo tea plus glyburide vs double placebo
Dose
Leaf tea daily (preparation in the paper)
Duration
28 days
Source
Reference 1 · PubMed 16476114 (opens PubMed)

What the numbers add up to

Each point is worked out from the data and the sources numbered on this page, with the arithmetic shown under it. It adds no new data and is not medical advice.

The only controlled jamun trials were null

Both placebo-controlled trials of jamun alone found no glucose effect; the positive signals come from a pooled analysis of related plants and an uncontrolled blend study.1234

How we got this: Design and results of the four cited human studies

Studied doses

Doses used in research, shown against the official limits. They describe the studies, not a recommendation for you.

Studied doses in research, not advice. These are amounts used in research, not personal advice. Your clinician or pharmacist can say what fits you.

Doses studied in human trials

Doses studied in human trials ranged from daily leaf tea for 28 days to 500 mg twice daily of jamun alone for 3 months and 1-2 g a day of a seed-containing herb blend for 3 months.183

Interactions and safety

Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.

What Jamun meets

1 cited row 2 tested together

Medicines 1

Jamun1 medicine · 2 supplements

Supplements and foods 2

  • Reference summary
  • Tested together in a graded trial
Also cited: 2 tested together

  1. Diabetes medicines

    • ReviewReference summary

      Diabetes medicines, for example Insulin, glyburide, glimepiride, glipizide, pioglitazone: Natural Medicines rates this a moderate interaction: jamun seed and bark extracts might lower blood sugar, adding to diabetes drugs and risking low blood sugar, so glucose should be monitored closely and drug doses may need adjusting. The leaf-tea trials found no glucose-lowering effect.

      Source 7, RxList (2026); Source 1, J Clin Pharm Ther (2006)

  2. Bitter melonBitter melon page

    • Tested together

      Blood glucose in type 2 diabetes (herb blend). Graded on the Jamun page; tested together is not a claim that they work better together.

  3. FenugreekFenugreek page

    • Tested together

      Blood glucose in type 2 diabetes (herb blend). Graded on the Jamun page; tested together is not a claim that they work better together.

Rows as our evidence profiles cite them; links stay on this site. Line weight shows what backs a row, not how serious an interaction is. No line means none was found in our sources, not that a combination is safe. Not medical advice: ask your pharmacist.

Interactions

1 agent
Published interactions, grouped by kind
AgentWhat the source saysEvidence
Medicines1
Diabetes medicinese.g. Insulin, glyburide, glimepiride, glipizide, pioglitazoneNatural Medicines rates this a moderate interaction: jamun seed and bark extracts might lower blood sugar, adding to diabetes drugs and risking low blood sugar, so glucose should be monitored closely and drug doses may need adjusting. The leaf-tea trials found no glucose-lowering effect.71Review

Check with what you take

Kept on this device only

Add what you take. We list every interaction our evidence profiles cite between Jamun and your picks, and between your picks.

Most cited:

Add a supplement or medicine you take to check it against Jamun.

Starting from one medicine? The interaction checker rates how serious each pair is, on a curated list of 19 entries for 11 medicines. This cabinet has no severity rating: it lists every interaction row our supplement pages cite.

Not medical advice, and no dosing advice. An empty result means no row we cite names that pair, by name or through a drug class we can link the medicine to, not that a combination is safe. Where our sources name only a group of medicines we cannot match, the cabinet says so. Ask your pharmacist before you combine supplements and medicines.

Who should be careful

3 groups
People with diabetes
If you take insulin or another glucose-lowering drug, adding jamun seed or bark extract could push blood sugar too low; check glucose more often and tell your clinician. The 2026 meta-analysis concluded jamun-type preparations are unproven and should not replace standard diabetes care.74
Pregnancy and breastfeeding
Not enough is known. Natural Medicines (via RxList) advises avoiding jamun during pregnancy and breastfeeding, LactMed has no entry, and the trials enrolled non-pregnant adults. The 2026 meta-analysis also found no long-term safety data.74
Before surgery
Because seed and bark extracts might lower blood sugar, Natural Medicines advises stopping jamun at least 2 weeks before scheduled surgery.7
Talk to your pharmacist or clinician before starting a supplement, especially if you take prescription medicines.

How to read the label

What to check on the Supplement Facts panel.

How to read the label

2 checks
Leaf, seed or fruit

The two placebo-controlled jamun trials used leaf tea and found nothing; seed powder was tested only inside a three-herb blend.123

Single herb or blend

Many products mix jamun with bitter melon, fenugreek or other herbs, as in the 2005 study; results for a blend cannot be credited to jamun.3

Have the bottle? Photograph its Supplement Facts panel and see each line, jamun included, beside the doses and forms the trials used in Label X-Ray.

Frequently asked questions

Short answers to common questions; the numbers link to the sources below.

Common questions

6 answers
Does jamun lower blood sugar?

Not in the trials of jamun alone. Leaf tea did not change fasting glucose in 27 people with type 2 diabetes over 28 days, nor glucose tolerance in 30 healthy volunteers.12

Can jamun replace diabetes medicine?

No. In a 28-day trial in 27 people with type 2 diabetes, glyburide lowered fasting glucose while jamun leaf tea did not, and the 2026 meta-analysis called jamun-type preparations promising but unproven add-ons, not alternatives to standard care.14

Does eating jamun fruit lower blood sugar?

There is no human trial of the fruit. Natural Medicines notes that seed and bark extracts contain compounds that might lower blood sugar, while leaf and fruit extracts don't seem to; the two placebo-controlled jamun trials cited here used leaf tea and found no effect.712

Is jamun safe?

Short trials reported no lab safety problems, but long-term safety is unstudied. Seed and bark extracts might add to diabetes drugs and cause low blood sugar, and the review says jamun should not replace standard diabetes care.147

What about jamun seed powder?

It has been tested only in blends. A 3-month study of bitter gourd, jamun seed and fenugreek powder in 60 men reported lower glucose, but it had no control group.3

What does the latest review say?

A 2026 meta-analysis of 13 trials of jamun and related plants found fasting glucose fell 14.4 mg/dL, with no significant change in HbA1c and low to very low certainty.4

Sources

8 sources: trial abstracts, NIH fact sheets and reference databases. Numbers in the text link here.

Sources cited on this page

8 sources
  1. 1The efficacy of folk medicines in the management of type 2 diabetes mellitus: results of a randomized controlled trial of Syzygium cumini (L.) Skeels.RCT J Clin Pharm Ther, 2006 · PMID 16476114
  2. 2Absence of antihyperglycemic effect of jambolan in experimental and clinical models.RCT J Ethnopharmacol, 2000 · PMID 10904184
  3. 3Effect of supplementation of traditional medicinal plants on blood glucose in non-insulin-dependent diabetics: a pilot study.Open-label trial J Med Food, 2005 · PMID 16379570
  4. 4Efficacy and Safety of Syzygium cumini and Related Myrtaceae Interventions for Dysglycemia: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.Meta-analysis Foods, 2026 · PMID 42450449
  5. 5Comprehensive analysis of Syzygium cumini L. pomace extract as an α-amylase inhibitor: In vitro inhibition, kinetics, and computational studies.Animal study Bioorg Chem, 2025 · PMID 40339502
  6. 6The effect of Syzygium cumini (L.) skeels on post-prandial blood glucose levels in non-diabetic rats and rats with streptozotocin-induced diabetes mellitus.Animal study J Ethnopharmacol, 1997 · PMID 9201610
  7. 7Jambolan (Natural Medicines monograph)Database RxList, 2026 · rxlist.com
  8. 8Combined effect of Withania somnifera and Syzygium cumini on hyperlipidemic patients.Open-label trial Pak J Pharm Sci, 2026 · PMID 42170977

What changed

Every dated change to this page: what changed, who made it and why.

Change log

3 entries
Dated changes to this page
DateChangeWho and why
evidence, key facts, studied doses, who should avoid, FAQ, questions, relatedAdded a blood-lipid row (a small 2026 study of 500 mg twice daily for 3 months with within-group falls in cholesterol and triglycerides, no reported comparison with atorvastatin; grade D, mixed against the null pooled lipid result) and a matching key fact; corrected the 2026 meta-analysis row's trial count to 13. Rewrote the pregnancy note: Natural Medicines (via RxList) advises avoiding jamun in pregnancy and breastfeeding, and LactMed has no entry. Added FAQ items on replacing diabetes medicine and on the fruit, page questions, and links to gymnema, ashwagandha and the metabolic goal hub. PubMed search for 2023–2026 meta-analyses and RCTs found nothing else on jamun alone: a 2022 open-label prediabetes trial used homeopathic mother tinctures with jamun as one of three options and was not added. Interactions re-checked: LiverTox, LactMed, NCCIH and MedlinePlus have no jamun entries; the diabetes-medicine interaction stays.Writer: Kymata Health EditorialTrigger: A–Z audit against docs/supplements/AUDIT-STANDARD.md
allInitial editorial evidence review. Every PMID checked against NCBI E-utilities esummary (title, year, journal) and each cited abstract read; numbers taken from the abstracts. The 2004 Diabetes Care letter by the same group was not cited because PubMed has no abstract. Mechanism uses an in-vitro enzyme study and a null rat study, labelled as such. Where to buy: we didn’t list a product; none of the stores we checked sells jamun.Writer: Kymata Health EditorialTrigger: new page
interactionsSafety review: added the diabetes-medicine interaction and low blood sugar caution (Natural Medicines via RxList) and the pre-surgery stop advice; noted the leaf-tea trials were null.Writer: Kymata Health EditorialTrigger: safety review

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