Home Ingredients 4-Hydroxy-L-Isoleucine
Metabolic HealthAthletic Performance

4-Hydroxy-L-Isoleucine

Trigonella foenum-graecum
Evidence Level
Limited
3 Clinical Trials
4 Documented Benefits
2/5 Evidence Score

4-Hydroxy-L-Isoleucine (4-OH-Ile) is a non-proteinogenic amino acid found in fenugreek (Trigonella foenum-graecum) seeds at roughly 0.5–1% of seed weight. It is the leading candidate molecule behind fenugreek's traditional anti-diabetic reputation, acting as a glucose-dependent insulinotropic agent — meaning it stimulates pancreatic beta-cell insulin secretion only in the presence of elevated blood glucose, reducing the theoretical risk of hypoglycemia compared with broad insulin secretagogues. NNB Nutrition and several specialty ingredient suppliers produce standardized 4-hydroxy-L-isoleucine extracts targeting glycemic control and post-workout glucose disposal applications, although robust standalone human evidence remains limited.

Studied Dose Standalone human data limited; preclinical 18-50 mg/kg in rats. Fenugreek extracts standardized for 4-OH-Ile: 300-600 mg/day in humans.
Active Compound 4-Hydroxy-L-Isoleucine - non-proteinogenic branched-chain amino acid from fenugreek seeds; available as standardized extracts.

Benefits

Glucose-dependent insulin secretion support

Preclinical and human studies suggest 4-hydroxy-L-isoleucine stimulates insulin secretion only in the presence of elevated blood glucose. This glucose-dependence reduces the theoretical risk of supplement-induced hypoglycemia compared with non-selective insulin secretagogues.

Supported by Trial 1, Trial 2

Support for post-meal glycemic control

By enhancing insulin response selectively when glucose is high, 4-OH-Ile is positioned to support post-prandial glycemic control in individuals with normal or impaired glucose tolerance, complementing dietary carbohydrate management strategies.

Supported by Trial 2, Trial 1

Potential role in post-workout carbohydrate handling

The glucose-dependent insulinotropic action makes 4-OH-Ile a candidate ingredient in post-workout glucose-disposal formulas aiming to enhance carbohydrate uptake into muscle, although direct human ergogenic data is limited and effects should be expected to be modest.

Supported by Trial 1, Trial 2

Adjunct to fenugreek-based metabolic formulas

As the principal insulinotropic constituent of fenugreek seeds, 4-OH-Ile contributes to the metabolic effects of standardized fenugreek extracts used in glycemic-support products, alongside fiber components and trigonelline.

Supported by Trial 1

Mechanism of action

1

Direct stimulation of pancreatic beta-cell insulin release

Isolated islet and animal pancreas studies show 4-OH-Ile directly enhances insulin secretion from pancreatic beta-cells. The effect depends on extracellular glucose concentration — minimal at low glucose and pronounced at elevated glucose — distinguishing it from non-selective secretagogues like sulfonylureas.

2

Activation of insulin signalling in peripheral tissues

4-OH-Ile has been reported to activate insulin signalling pathways in rat liver and skeletal muscle (insulin receptor substrate, PI3K, Akt), supporting peripheral insulin sensitization in addition to its insulinotropic action at the beta-cell.

3

Improvement in glucose tolerance

Animal and isolated tissue work shows 4-OH-Ile improves glucose tolerance in normal and insulin-resistant models. The combination of glucose-dependent insulin secretion and improved peripheral signalling provides a coherent mechanistic basis for fenugreek's metabolic effects.

Clinical trials

1
4-Hydroxyisoleucine as a Novel Insulin Secretion Potentiator

Landmark characterization of 4-hydroxyisoleucine as a novel amino acid potentiator of insulin secretion. Experiments in isolated rat and human pancreatic islets evaluating glucose-dependent insulin release. Published in Diabetes.

Isolated rat and human pancreatic islets; preclinical mechanism trial.

4-Hydroxyisoleucine stimulated insulin secretion in a glucose-dependent manner in both rat and human islets, with minimal effect at low glucose and pronounced effect at elevated glucose. Identified 4-OH-Ile as the principal insulinotropic constituent of fenugreek seeds.

2
4-Hydroxyisoleucine Insulinotropic and Antidiabetic Properties

Experimental study of 4-hydroxyisoleucine's insulinotropic and antidiabetic actions in normal and diabetic rats. Published in American Journal of Physiology.

Normal and diabetic rat models; controlled experimental design.

4-Hydroxyisoleucine produced glucose-dependent insulin release and improved glucose tolerance in diabetic rats. Activity was preserved across normal and diabetic states, supporting it as the lead candidate antidiabetic molecule from fenugreek.

3
4-Hydroxyisoleucine (ID-1101) Activates Insulin Signaling in Rat

Mechanistic study evaluating the effects of synthetic 4-hydroxyisoleucine (ID-1101) on insulin signalling pathways in rat tissues. Published in American Journal of Physiology — Endocrinology and Metabolism.

Rat model; mechanistic experimental design.

4-Hydroxyisoleucine activated insulin signalling pathways including insulin receptor substrate-1 phosphorylation and downstream PI3K/Akt cascade in rat tissues, supporting peripheral insulin sensitization as a complementary mechanism alongside its insulinotropic action.

Side effects and drug interactions

Common Potential side effects

Limited standalone human safety data; most safety information derives from fenugreek extract trials.
Possible GI symptoms (mild diarrhea, bloating) reported with fenugreek seed products.
Distinctive maple-syrup odor of fenugreek may appear in sweat or urine.
Theoretical risk of hypoglycemia in combination with strong antidiabetic drugs despite glucose-dependent action.
Pregnancy: fenugreek has uterotonic effects; 4-OH-Ile-containing products should be avoided in pregnancy.

Important Drug interactions

Insulin and sulfonylureas — additive insulin/glucose-lowering effect; monitor closely.
Other antidiabetic agents (metformin, GLP-1 agonists, SGLT2 inhibitors) — monitor glycemic control when combining.
Warfarin — fenugreek seed has anticoagulant constituents; coordinate INR monitoring.
MAO inhibitors — theoretical interaction with branched-chain amino acid metabolism; use cautiously.

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Frequently asked questions about 4-Hydroxy-L-Isoleucine

What is 4-hydroxyisoleucine used for?

4-hydroxyisoleucine is an amino acid found in fenugreek seeds, marketed for blood-sugar support because it may stimulate insulin release in response to glucose. It is the compound behind some of fenugreek's metabolic effects.

What is 4-hydroxyisoleucine good for?

It is studied for supporting healthy blood sugar by enhancing insulin secretion, and is used in metabolic and post-workout (nutrient-partitioning) supplements. It is usually obtained from standardized fenugreek extracts.

How much 4-hydroxyisoleucine should I take?

It is delivered through standardized fenugreek extracts; follow product labeling. Doses vary by the extract's standardization.

Is 4-hydroxyisoleucine safe?

As a fenugreek-derived compound it is generally well tolerated. Because it can lower blood sugar, those on diabetes medication should monitor and check with a doctor. Pregnant women should avoid medicinal fenugreek doses.

What is 4-Hydroxy-L-Isoleucine?

4-Hydroxy-L-Isoleucine (4-OH-Ile) is a non-proteinogenic amino acid found in fenugreek (Trigonella foenum-graecum) seeds at roughly 0.5–1% of seed weight. It is the leading candidate molecule behind fenugreek's traditional anti-diabetic reputation, acting as a glucose-dependent insulinotropic agent — meaning it stimula…

What is 4-Hydroxy-L-Isoleucine used for?

4-Hydroxy-L-Isoleucine is researched primarily for Metabolic Health and Athletic Performance. Preclinical and human studies suggest 4-hydroxy-L-isoleucine stimulates insulin secretion only in the presence of elevated blood glucose.

What is the recommended dosage of 4-Hydroxy-L-Isoleucine?

The clinically studied dose is Standalone human data limited; preclinical 18-50 mg/kg in rats. Fenugreek extracts standardized for 4-OH-Ile: 300-600 mg/day in humans. Always follow the product label and check with a healthcare provider for personal advice.

Is 4-Hydroxy-L-Isoleucine safe, and does it have side effects?

For most healthy adults, 4-Hydroxy-L-Isoleucine is well tolerated at studied doses. Reported effects can include: Limited standalone human safety data; most safety information derives from fenugreek extract trials. Possible GI symptoms (mild diarrhea, bloating) reported with fenugreek seed products. It may also interact with some medications. 4-Hydroxy-L-Isoleucine is not right for everyone, so check with a healthcare provider first if you are pregnant or breastfeeding, have a medical condition, or take prescription medication.

Does 4-Hydroxy-L-Isoleucine interact with any medications?

Possible interactions include: Insulin and sulfonylureas — additive insulin/glucose-lowering effect; monitor closely. Other antidiabetic agents (metformin, GLP-1 agonists, SGLT2 inhibitors) — monitor glycemic control when combining. If you take prescription medication, check with a pharmacist or doctor before using it.

How strong is the scientific evidence for 4-Hydroxy-L-Isoleucine?

NutraSmarts rates the evidence for 4-Hydroxy-L-Isoleucine as Limited (2 out of 5). It is backed by 3 clinical trials and 3 cited references summarized on this page. A higher rating reflects more, larger, and better-designed human studies.

References(3 citations)

Evidence ratings on NutraSmarts are based on the totality of human clinical research, with emphasis on randomized controlled trials, meta-analyses, and systematic reviews. The references below directly support claims made throughout this page.

  1. Sauvaire Y, Petit P, Broca C, Manteghetti M, Baissac Y, Fernandez-Alvarez J, Gross R, Roye M, Leconte A, Gomis R, Ribes G. 4-Hydroxyisoleucine: a novel amino acid potentiator of insulin secretion. Diabetes. 1998;47(2):206-10. doi: 10.2337/diab.47.2.206.PubMedUsed to support: Foundational characterization — 4-hydroxyisoleucine stimulated insulin secretion in a glucose-dependent manner in isolated rat and human pancreatic islets, identifying it as the principal insulinotropic constituent of fenugreek seeds.
  2. Broca C, Gross R, Petit P, Sauvaire Y, Manteghetti M, Tournier M, Masiello P, Gomis R, Ribes G. 4-Hydroxyisoleucine: experimental evidence of its insulinotropic and antidiabetic properties. Am J Physiol. 1999;277(4):E617-23. doi: 10.1152/ajpendo.1999.277.4.E617.PubMedUsed to support: Experimental rat study — 4-hydroxyisoleucine produced glucose-dependent insulin release and improved glucose tolerance in diabetic rat models, supporting its insulinotropic and antidiabetic properties.
  3. Broca C, Breil V, Cruciani-Guglielmacci C, Manteghetti M, Rouault C, Derouet M, Rizkalla S, Pau B, Petit P, Ribes G, Ktorza A, Gross R, Reach G, Taouis M. Insulinotropic agent ID-1101 (4-hydroxyisoleucine) activates insulin signaling in rat. Am J Physiol Endocrinol Metab. 2004;287(3):E463-71. doi: 10.1152/ajpendo.00163.2003.PubMedUsed to support: Mechanistic rat study — synthetic 4-hydroxyisoleucine (ID-1101) activated insulin signalling pathways (IRS-1, PI3K, Akt) in rat tissues, supporting peripheral insulin sensitization as a complementary mechanism to its insulinotropic action.