Poly-γ-glutamic acid (γ-PGA)

Q: Does γ-PGA help calcium absorption?

In one single-dose study of 24 postmenopausal women, adding 60 mg to a calcium drink raised absorption from about 35% to 39%. No trial has tested whether this changes bone density.

Q: Does it lower cholesterol?

An 8-week trial of 150 mg/day in 20 women found only a non-significant tendency toward lower total and LDL cholesterol.

Q: Does γ-PGA help sleep?

Not on its own. In a 1-month crossover trial, 600 mg/day of γ-PGA alone did not change sleep length or quality; only γ-PGA combined with vitamin B6 showed a small gain of about 0.27 hours (grade D).

Q: Is it safe?

No health agency has reviewed γ-PGA supplements. In the largest trial (4 weeks), side effects were as common as with placebo and none were severe. The clearest risk is allergy: γ-PGA is the allergen in natto allergy, which can cause delayed anaphylaxis, especially in surfers sensitized by jellyfish stings.

Q: Is γ-PGA the same as MSG?

No. Both contain glutamic acid, but γ-PGA is a large polymer, while MSG is the sodium salt of single glutamate molecules.

Q: What is poly-γ-glutamic acid?

A long chain of glutamic acid units made by Bacillus bacteria. It forms part of the sticky strings of natto and is also produced by fermentation for supplements.

Also called gamma-PGA, γ-PGA, poly-gamma-glutamic acid, polyglutamic acid, natto polymer.

Best grade B across 4 graded outcomes Other Last checked Oct 21, 2026

The short answer

From 8 sources

Poly-γ-glutamic acid is the sticky polymer in natto, made by Bacillus bacteria. Human trials are few and mostly industry-funded: one dose raised calcium absorption in 24 postmenopausal women, an 8-week trial saw only a cholesterol trend, and a 195-woman trial in mild cervical lesions reported more regression. It is the main allergen in natto allergy.

Every graded outcome on this page

4 rows · line = participants

Grade BRegression of mild cervical lesions (CIN 1) and HPV clearanceCervical lesionsn 195
Grade DCalcium absorption after a single doseCalcium absorptionn 24
Grade DTotal and LDL cholesterolCholesteroln 20
Grade DSleep duration and qualitySleepn 16

Key facts

Calcium absorption: 60 mg γ-PGA with a calcium drink raised fractional calcium absorption from 34.6% to 39.1% in 24 postmenopausal women (single dose)¹
Cholesterol: 150 mg/day for 8 weeks in 20 women gave only a non-significant tendency toward lower total and LDL cholesterol²
Cervical lesions (CIN 1): 1,500 mg/day for 4 weeks: 42.4% histologic regression at 12 weeks vs 27.1% with placebo in 195 women³
Allergy: γ-PGA is the allergen behind natto allergy, which often causes anaphylaxis about half a day after eating; in a Japanese clinic, 11 of 13 natto-allergic patients were surfers, likely sensitized by jellyfish stings^6,7
Industry funding: The CIN 1 trial was funded by Bioleaders, which develops γ-PGA products; the calcium study's lead author was at Ajinomoto^1,3
Agency safety reviews: No ODS, NCCIH, LactMed, LiverTox, Health Canada or EMA monograph covers γ-PGA⁴

What it is

Poly-γ-glutamic acid (γ-PGA) is a sticky glutamic-acid polymer made by Bacillus bacteria, found in natto and sold in supplements.

How it works

Proposed

γ-PGA keeps calcium soluble in the gut in lab and animal work, which is the proposed reason it raised calcium absorption in one human study. In rats fed a high-fat diet it lowered cholesterol and fat mass (animal data). Immune effects proposed for cervical lesions were not confirmed: NK-cell activity did not differ from placebo.^1,2,3

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.

Poly-γ-glutamic acid (γ-PGA) forms compared

2 forms

Poly-γ-glutamic acid (γ-PGA) forms compared: 2 forms by 3 attributes. Empty cells are labelled No data yet, or Not graded in the evidence row.
2 forms	γ-PGA powder or capsules (often high molecular weight)	Natto (fermented soybeans)
Absorption in people	No head-to-head human data²	Not studied.⁵
GI tolerance	In the 4-week CIN 1 trial, adverse events (mostly headache, cough, premenstrual pain) were as common as with placebo and none were severe; the other human studies were too small or short to judge safety.³	Eaten as a traditional Japanese food; γ-PGA content varies by product.⁵
Studied for	Calcium absorption, cholesterol, mild cervical lesions	After-meal blood sugar (one crossover meal test of high-γ-PGA natto)

γ-PGA powder or capsules (often high molecular weight)
Absorption in people
No head-to-head human data²
GI tolerance
In the 4-week CIN 1 trial, adverse events (mostly headache, cough, premenstrual pain) were as common as with placebo and none were severe; the other human studies were too small or short to judge safety.³
Studied for
Calcium absorption, cholesterol, mild cervical lesions
Natto (fermented soybeans)
Absorption in people
Not studied.⁵
GI tolerance
Eaten as a traditional Japanese food; γ-PGA content varies by product.⁵
Studied for
After-meal blood sugar (one crossover meal test of high-γ-PGA natto)

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

4 graded outcomes, largest study first

4 graded outcomes: 2 improved, 2 no effect. The largest, a 2019 randomized trial of 195 people on regression of mild cervical lesions (CIN 1) and HPV clearance, found an improvement.

By sizeTable

1Regression of mild cervical lesions (CIN 1) and HPV clearance

Improved · Grade B · RCT, 195 people, 2019

Women with cervical intraepithelial neoplasia 1 (CIN 1), multicenter phase II trial in Korea

Dose, result and source

Every graded outcome on this page, largest study first
Outcome	Found	People	Study	Who was studied
Regression of mild cervical lesions (CIN 1) and HPV clearance	Improved	195	Grade B · RCT, 2019	Women with cervical intraepithelial neoplasia 1 (CIN 1), multicenter phase II trial in Korea
Calcium absorption after a single dose	Improved	24	Grade D · Crossover RCT, 2007	Healthy non-smoking postmenopausal women (mean age 56)
Total and LDL cholesterol	No effect	20	Grade D · RCT, 2011	Women (human arm of a combined rat-and-human study, Korea)
Sleep duration and quality	No effect	16	Grade D · Crossover RCT, 2021	Healthy Korean adults

Every graded row

4 rows

Form tested

Showing 4 of 4 outcomes. Human trials only.

Grade BRegression of mild cervical lesions (CIN 1) and HPV clearanceCervical lesionsMore regression vs placeboRCT
n 195 · 2019

Improved Histologic regression of CIN 1 in 42.4% with γ-PGA vs 27.1% with placebo (intention-to-treat, p = 0.018); high-risk HPV cleared more often with γ-PGA. NK-cell activity and other immune markers did not differ between groups.

Design: RCT, n = 195, 2019
Population: Women with cervical intraepithelial neoplasia 1 (CIN 1), multicenter phase II trial in Korea
Form: Oral γ-PGA
Dose: 1,500 mg/day
Duration: 4 weeks, assessed at 12 weeks
Source: Reference 3 · PubMed 31220105 (opens PubMed)

Grade DCalcium absorption after a single doseCalcium absorptionAbsorption up about 4.5 pointsCrossover RCT
n 24 · 2007

Improved Fractional calcium absorption, measured with stable isotopes, was 39.1% with γ-PGA vs 34.6% without (p < 0.01); the rise was larger in women with lower baseline absorption. Bone density was not measured.

Design: Crossover RCT, n = 24, 2007
Population: Healthy non-smoking postmenopausal women (mean age 56)
Form: γ-PGA in orange juice with 200 mg calcium (as calcium carbonate)
Dose: 60 mg, single dose
Duration: Single test day, repeated after a 3-4 week washout
Source: Reference 1 · PubMed 18187428 (opens PubMed)

Grade DTotal and LDL cholesterolCholesterolNo significant changeRCT
n 20 · 2011

No effect Total and LDL cholesterol showed only a tendency to fall vs placebo; the abstract reports no significant difference.

Design: RCT, n = 20, 2011
Population: Women (human arm of a combined rat-and-human study, Korea)
Form: High-molecular-weight γ-PGA
Dose: 150 mg/day
Duration: 8 weeks
Source: Reference 2 · PubMed 21791965 (opens PubMed)

Grade DSleep duration and qualitySleepNo change aloneCrossover RCT
n 16 · 2021

No effect γ-PGA alone did not change sleep duration or Pittsburgh Sleep Quality Index scores versus placebo; only the group given γ-PGA with 100 mg vitamin B6 slept about 0.27 hours longer with slightly better scores. No side effects were observed.

Design: Crossover RCT, n = 16, 2021
Population: Healthy Korean adults
Form: γ-PGA supplement
Dose: 600 mg/day
Duration: 1 month per period, crossover with placebo
Source: Reference 8 · PubMed 34093972 (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.

Four small trials, four different questions

Each human trial tested a different outcome (calcium absorption, cholesterol, cervical lesions, sleep), so no result has been confirmed by a second trial.^1,2,3,8

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 a single 60 mg dose with a calcium drink to 150 mg/day for 8 weeks, 600 mg/day for 1 month and 1,500 mg/day for 4 weeks. These are research doses, not recommendations.^1,2,3,8

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 Poly-γ-glutamic acid meets

0 cited rows 1 tested together

Medicines 0

No medicine rows in our sources.

Poly-γ-glutamic acid0 medicines · 1 supplement

Supplements and foods 1

Tested together in a graded trial

Also cited: 1 tested together

CalciumCalcium page
- Tested together
  Calcium absorption after a single dose. Graded on the Poly-γ-glutamic acid page; tested together is not a claim that they work better together.

Interactions

0 agents

None found in our sources.

Check with what you take

Kept on this device only

Add what you take. We list every interaction our evidence profiles cite between Poly-γ-glutamic acid and your picks, and between your picks.

Add a supplement or medicine

Most cited:

Add a supplement or medicine you take to check it against Poly-γ-glutamic acid.

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.

Who should be careful

5 groups

Natto allergy or jellyfish-sting sensitization: γ-PGA is the main allergen in natto allergy, an IgE allergy that often causes anaphylaxis about half a day after eating. Sensitization was strongly linked to surfing and other marine sports, probably through jellyfish stings, which also contain γ-PGA. γ-PGA is also used in cosmetics and medicines, and a case report advises allergic people to avoid γ-PGA products.^6,7
Pregnancy and breastfeeding: No agency monograph covers γ-PGA supplements, and LactMed has no entry for it. NCCIH notes that many dietary supplements have not been tested in pregnant or nursing women.⁴
People on medicines: No drug-interaction data were found in ODS, NCCIH, LactMed, LiverTox, Health Canada or EMA sources. NCCIH advises telling your health care providers about every supplement you use.⁴
Abnormal cervical screening: The CIN 1 trial was a 4-week study under specialist follow-up. A supplement is not a substitute for the follow-up a clinician arranges after an abnormal Pap or HPV test.^3,4
Before surgery: NCCIH advises telling your surgical team about all supplements well before an operation.⁴

Frequently asked questions

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

Common questions

6 answers

Does γ-PGA help calcium absorption?

In one single-dose study of 24 postmenopausal women, adding 60 mg to a calcium drink raised absorption from about 35% to 39%. No trial has tested whether this changes bone density.¹

Does it lower cholesterol?

An 8-week trial of 150 mg/day in 20 women found only a non-significant tendency toward lower total and LDL cholesterol.²

Does γ-PGA help sleep?

Not on its own. In a 1-month crossover trial, 600 mg/day of γ-PGA alone did not change sleep length or quality; only γ-PGA combined with vitamin B6 showed a small gain of about 0.27 hours (grade D).⁸

Is it safe?

No health agency has reviewed γ-PGA supplements. In the largest trial (4 weeks), side effects were as common as with placebo and none were severe. The clearest risk is allergy: γ-PGA is the allergen in natto allergy, which can cause delayed anaphylaxis, especially in surfers sensitized by jellyfish stings.^3,4,6,7

Is γ-PGA the same as MSG?

No. Both contain glutamic acid, but γ-PGA is a large polymer, while MSG is the sodium salt of single glutamate molecules.

What is poly-γ-glutamic acid?

A long chain of glutamic acid units made by Bacillus bacteria. It forms part of the sticky strings of natto and is also produced by fermentation for supplements.^2,5

Sources

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

Sources cited on this page

8 sources

1Acute effect of poly-gamma-glutamic acid on calcium absorption in post-menopausal women.Crossover RCT J Am Coll Nutr, 2007 · PMID 18187428
2High molecular weight poly-gamma-glutamic acid regulates lipid metabolism in rats fed a high-fat diet and humans.RCT J Microbiol Biotechnol, 2011 · PMID 21791965
3Short-term clinical and immunologic effects of poly-gamma-glutamic acid (γ-PGA) in women with cervical intraepithelial neoplasia 1 (CIN 1): A multicenter, randomized, double blind, phase II trial.RCT PLoS One, 2019 · PMID 31220105
4Using Dietary Supplements WiselyFact sheet National Center for Complementary and Integrative Health (NCCIH), 2019 · nccih.nih.gov
5The Possibility of Suppression of Increased Postprandial Blood Glucose Levels by Gamma-Polyglutamic Acid-Rich Natto in the Early Phase after Eating: A Randomized Crossover Pilot Study.Crossover RCT Nutrients, 2020 · PMID 32230729
6Surfing as a risk factor for sensitization to poly(γ-glutamic acid) in fermented soybeans, natto, allergy.Observational Allergol Int, 2018 · PMID 29175280
7Natto (fermented soybeans)-induced anaphylaxis in a surfer with the possibility of sensitization to poly(γ-glutamic acid) from cutaneous exposure to jellyfish sting: a case report.Observational Int J Emerg Med, 2024 · PMID 38500076
8Effects of poly-gamma-glutamic acid and vitamin B(6) supplements on sleep status: a randomized intervention study.Crossover RCT Nutr Res Pract, 2021 · PMID 34093972

What changed

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

Change log

2 entries

Dated changes to this page
Date	Change	Who and why
Oct 21, 2026summary, key facts, evidence, studied doses, who should be careful, insights, FAQ	Added the natto allergy risk (γ-PGA is the allergen; PMIDs 29175280, 38500076) to who should be careful, key facts and the FAQ, and a 2021 sleep trial in which γ-PGA alone had no effect (PMID 34093972) as a graded row. No newer trial or meta-analysis of γ-PGA alone found; interactions re-checked: none published, LactMed has no entry.	Writer: Kymata Health EditorialTrigger: A–Z page audit
Oct 14, 2026all	Initial editorial evidence review	Writer: Kymata Health EditorialTrigger: new page

Supplement & Nutrient Encyclopedia. Educational information only; it is not medical advice and does not replace a clinician. Dietary supplements are not intended to diagnose, treat, cure or prevent any disease. Statements about supplements have not been evaluated by the FDA.

Poly-γ-glutamic acid (γ-PGA)

Medicines 0

Supplements and foods 1

CalciumCalcium page