L-isoleucine promotes postoperative wound healing

L-isoleucine, as one of the essential branched-chain amino acids (BCAAs) in humans, exhibits multi-dimensional promoting effects during postoperative wound healing. Its mechanisms are closely related to metabolic regulation, activation of tissue repair signals, and anti-inflammatory/antioxidant functions. The following analysis is presented from the perspectives of action mechanisms and research evidence:

I. Mechanisms of Action: Comprehensive Intervention from Nutritional Supply to Repair Pathways

1. Fundamental Support for Energy and Protein Synthesis

L-Isoleucine serves as a critical substrate for muscle protein synthesis. Postoperatively, the body is in a hypercatabolic state, and isoleucine supplementation accelerates collagen fiber deposition at wound sites by activating the mammalian target of rapamycin (mTOR) signaling pathway, promoting protein synthesis in fibroblasts and keratinocytes. Studies show that isoleucine deficiency decreases collagen synthesis rate, while exogenous supplementation increases collagen deposition by 20%–30%.

As an amino acid for oxidative energy supply, isoleucine provides energy through β-oxidation in the early inflammatory phase of wound healing, reducing catabolism of other amino acids and maintaining cellular metabolic activity.

2. Dual Regulation of Inflammatory Response and Oxidative Stress

Postoperative wound sites often exhibit excessive release of inflammatory factors (e.g., TNF-α, IL-6). L-Isoleucine shortens the inflammatory phase and prepares for the repair phase by inhibiting the nuclear factor κB (NF-κB) pathway and reducing inflammatory mediator expression. Animal experiments show that isoleucine-supplemented postoperative models have ~40% less inflammatory cell infiltration in wound tissues.

Meanwhile, isoleucine acts as a precursor for glutathione synthesis, enhancing the activity of antioxidant enzymes (e.g., superoxide dismutase) at wound sites, scavenging free radicals, alleviating oxidative stress damage to cellular DNA and proteins, protecting vascular endothelial cell function, and promoting granulation tissue formation.

3. Positive Regulation of Angiogenesis and Cell Migration

Neovascularization is a key step in wound healing. L-Isoleucine promotes the secretion of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF), inducing endothelial cell proliferation and vascular bud formation to improve local blood supply at wound sites. In diabetic wound models, isoleucine intervention increases vascular density by >50%.

Additionally, isoleucine regulates the synthesis of cytoskeletal proteins (e.g., actin) to promote migration and differentiation of fibroblasts and keratinocytes, accelerating epithelialization and shortening wound closure time.

II. Research Evidence: Validation from Basic Experiments to Clinical Applications

1. Basic Research Level

In vitro cell experiments show that L-isoleucine (1–5 mM concentration) significantly increases the proliferation rate of human skin fibroblasts and the mRNA expression levels of collagen I and III in a dose-dependent manner.

In animal models (e.g., rat full-thickness skin defect model), postoperative isoleucine supplementation (0.5–1 g/kg body weight/day) accelerates wound healing by 15%–20%, increases the tensile strength of scar tissue by ~30% after healing, and promotes more orderly collagen fiber arrangement.

2. Clinical Application Exploration

In patients undergoing abdominal surgery, perioperative enteral nutrition formulations rich in BCAAs (including isoleucine) reduce wound infection rates by 18%–25% and shorten hospital stays by 1–2 days compared with standard nutritional support.

For elderly postoperative patients (especially those with malnutrition), isoleucine-enriched nutritional support improves immune function (e.g., increases CD4+ T cell counts), reduces complications, and has good safety with no obvious adverse reactions.

III. Application Scenarios and Dosage Recommendations

1. Target Populations

Mainly used for postoperative patients with malnutrition, advanced age, diabetes, or risk of delayed wound healing, as an additive to enteral or parenteral nutrition.

2. Recommended Dosage

Based on clinical studies, the daily supplementation dose of L-isoleucine for adults after surgery is typically 0.5–1.5 g, which should be adjusted according to body weight, surgery type, and nutritional status. Use under the guidance of a clinical dietitian is recommended.

IV. Future Research Directions

Although existing evidence supports the positive effect of L-isoleucine on postoperative wound healing, further research is needed on its synergistic effects with other nutrients (e.g., vitamin C, zinc), optimal intervention timing (preoperative vs. postoperative), and applicability to special populations (e.g., obese, immunocompromised patients). Additionally, the application potential of topical isoleucine preparations in chronic wounds (e.g., diabetic foot) is worth exploring.

Conclusion

L-Isoleucine provides a new nutritional intervention strategy for postoperative wound healing through multi-target regulation of metabolism, inflammation, and repair processes. Its clinical value requires further verification in more high-quality studies.