Glutamic Acid
| Evidence Level: L5 | Predicted Indications: 10 |
Table of Contents
Glutamic Acid: From Parenteral Nutrition Component to Postmenopausal Osteoporosis
One-Sentence Summary
Glutamic acid is an amino acid found in parenteral nutrition (intravenous feeding) products marketed in South Africa. The TxGNN model predicts it may be useful for postmenopausal osteoporosis, with a very high model score. No study tests glutamic acid itself for this condition. The only linked trial is an unrelated osteoporosis drug trial, and the literature is mostly about vitamin K and other compounds. This is a research question, not a supported repurposing candidate.
Quick Overview
| Item | Content |
|---|---|
| Original Indication | Amino acid component of parenteral nutrition products (inferred from product names; the registrations carry no indication text) |
| Predicted New Indication | Postmenopausal osteoporosis |
| TxGNN Prediction Score | 99.34% |
| Evidence Level | L4 (one mouse study and one small human absorption study of a different compound; no clinical data on glutamic acid) |
| South Africa Market Status | Marketed |
| Number of SAHPRA Registrations | 6 |
| Recommended Decision | Hold |
Why is This Prediction Reasonable?
Currently, detailed mechanism of action data is not available. Glutamic acid is a naturally occurring amino acid supplied in parenteral nutrition mixtures. It is not a bone-active drug, and no established pathway links it to bone loss in postmenopausal women.
The indirect support is thin:
- A mouse ovariectomy study (PMID 26144993) reported that glutamic acid eased menopausal-like symptoms caused by estrogen deficiency. It is preclinical, and it is not a bone-outcome study in humans.
- A small human study (PMID 18187428) found that poly-gamma-glutamic acid affected calcium absorption. That polymer is a different compound, and the endpoint was acute absorption, not bone density or fractures.
- Many retrieved papers concern vitamin K, which helps convert glutamic acid residues inside proteins (such as osteocalcin) into a bone-active form. This is not evidence that giving glutamic acid as a supplement helps bone.
The high TxGNN score is therefore not backed by clinical data. The other nine predicted indications are weaker still. Most are L5 (prediction only). For glaucoma, the literature points to excess glutamate being harmful (retinal excitotoxicity), so any benefit is doubtful and safety is the concern.
Clinical Trial Evidence
| Trial Number | Phase | Status | Enrollment | Key Findings |
|---|---|---|---|---|
| NCT00048061 | Phase 3 | Completed | 1609 | Oral ibandronate (monthly vs daily) in postmenopausal osteoporosis, with vitamin D and calcium. Nothing links it to glutamic acid. It shows the indication is well studied, not that glutamic acid works. |
No SANCTR or PACTR records were retrieved.
Literature Evidence
| PMID | Year | Type | Journal | Key Findings |
|---|---|---|---|---|
| 19172219 | 2009 | Randomised open-label study | J Bone Miner Metab | Vitamin K2 (menatetrenone) vs calcium aspartate in 109 patients. K2 increased osteocalcin gamma-carboxylation. This is a vitamin K study, not glutamate. |
| 26144993 | 2015 | Preclinical (mouse) | Nutr Res | Glutamic acid eased estrogen-deficiency menopausal-like symptoms in ovariectomised mice. It is the only study of glutamic acid itself, and it is not in humans. |
| 18187428 | 2007 | Small human physiological study | J Am Coll Nutr | Poly-gamma-glutamic acid affected calcium absorption in post-menopausal women. It is a different compound with an acute endpoint. |
| 14529146 | 2003 | Clinical review | Keio J Med | Vitamin D3 and/or K2 for postmenopausal osteoporosis. Glutamic acid appears only as a protein residue. |
| 14584089 | 2003 | Clinical review | Yonsei Med J | Vitamin K2 combined with bisphosphonates. Not about glutamate. |
| 29437025 | 2018 | Genetic association | Endocr Metab Immune Disord Drug Targets | VKORC1 polymorphism and osteoporosis risk. Not about glutamate. |
| 34529430 | 2021 | Preclinical (materials) | Nano Lett | Bone-targeting polymer vesicles delivering estradiol. The polymer contains glutamic acid units, but only as a carrier component. |
| 39698319 | 2024 | Preclinical | Front Cell Infect Microbiol | Zhuanggu Shubi ointment and the gut-bone axis in postmenopausal osteoporosis. No glutamic acid link shown. |
| 40950804 | 2025 | Cohort (metabolomics) | J Diabetes Metab Disord | Amino acid profiles, ageing and sex hormones in elderly Iranians. Associational only. |
| 18414001 | 2008 | Genetic association | Mol Cells | SLC22A11 (hOAT4) variants in Korean women with osteoporosis. Not about glutamate treatment. |
South Africa Market Information
Six registrations are recorded, but only five entries are listed in the data, and two of them share registration number 41/25/0757. No approved-indication text was captured for any of them, and Essential Medicines List (EML) status is not stated in the data.
| Registration Number | Product Name | Dosage Form | Approved Indication |
|---|---|---|---|
| Reg. No. 41/25/0757 | Nutriflex Lipid Peri | Infusion | Not stated in the data |
| Reg. No. 41/25/0757 | Nutriflex lipid peri 1875ml | TPN | Not stated in the data |
| Reg. No. 52/25/0739 | Numeta G13E | Infusion | Not stated in the data |
| Reg. No. 52/25/0740 | Numeta G16E | Infusion | Not stated in the data |
| Reg. No. 49/25/0065 | Nutriflex Omega Specialized | Infusion | Not stated in the data |
All products are intravenous parenteral nutrition mixtures. No oral single-ingredient glutamic acid product was identified, so the route and formulation for an osteoporosis use are unresolved.
Safety Considerations
Please refer to the SAHPRA-approved Professional Information (PI) for safety information. Report adverse drug reactions to SAHPRA.
Two points from the literature bear on safety:
- Glutamate excitotoxicity is described in glaucoma (retinal ganglion cell death), so excess glutamate could be harmful in some conditions.
- Supplementation in pregnancy raises safety questions that no data address.
Conclusion and Next Steps
Decision: Hold
Rationale: The 99.34% model score is not supported by any clinical evidence for glutamic acid in postmenopausal osteoporosis. The only relevant data are one mouse study and a small absorption study of a different compound. The linked Phase 3 trial tests another drug, and most of the literature concerns vitamin K.
To proceed, the following is needed:
- The SAHPRA package insert warnings and contraindications (a blocking gap for safety screening)
- Mechanism of action data (for example from the DrugBank API) to test whether a bone-relevant pathway exists
- Preclinical bone data (bone density or turnover markers) for glutamic acid itself, not vitamin K or polymer forms
- A clear route and formulation, since only intravenous parenteral nutrition products are registered
- A decision on whether to pursue a higher-value prediction, since the other listed indications are mostly prediction-only or point toward possible harm
This report is for research reference only and does not constitute medical advice. Repurposing candidates require clinical validation before any use.
Disclaimer
This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.