Wound healing is metabolically demanding. Collagen synthesis, new blood vessel formation, and immune defence all depend on adequate energy, protein, and micronutrients. In people with diabetes, a foot ulcer often develops against a background of older age, kidney disease, poor appetite, or food insecurity, so nutritional deficits may be present before the wound appears. Nutrition is therefore a plausible, modifiable contributor to diabetic foot ulcer (DFU) healing. The practical question is how strong the evidence is for assessing and supplementing it.
Nutritional Screening in People With Diabetic Foot Ulcers
A guidance document from the American Limb Preservation Society, Nutrition Interventions in Adults with Diabetic Foot Ulcers (Armstrong and colleagues, 2022), recommends an individualized nutrition care plan for people with a DFU or at risk of one, particularly when malnutrition is present or suspected. It supports formal screening with validated tools such as the Malnutrition Universal Screening Tool (MUST), the Mini Nutritional Assessment (MNA), and the Nutritional Risk Index, followed by fuller assessment when risk is identified. It also advises reviewing dietary intake at each visit, with a target of meeting more than 75% of estimated energy, protein, and fluid needs, and considering oral nutritional supplements early in higher-risk patients.
A 2023 systematic review of 15 studies (Sonko, Southeast Asia Nursing Research) reported that MUST and MNA were effective at identifying nutritional deficits that could impede DFU healing, while noting that these tools still need standardization for routine use in this population. Screening is inexpensive and low-risk, which is why it is the best-supported nutritional step in current guidance, even though trials showing that screening itself improves healing are lacking.
What Trials of Supplements Show
The Cochrane review by Moore, Corcoran, and Patton (Cochrane Database of Systematic Reviews, 2020) examined nutritional interventions for treating DFUs. Each comparison rested on a single small trial, and the certainty of evidence was rated very low throughout. The two trials with healing as an outcome did not show a clear benefit:
- A 1 kcal/mL oral supplement enriched with vitamins and minerals (53 participants) produced healing at six months in 37% versus 46% with placebo (risk ratio 0.80, 95% CI 0.42 to 1.53).
- A combination of arginine, glutamine, and beta-hydroxy-beta-methylbutyrate (270 participants) produced healing at 16 weeks in 50% versus 46% with placebo (risk ratio 1.09, 95% CI 0.85 to 1.40).
Several small trials of zinc sulphate, magnesium oxide, flaxseed-derived omega-3 fatty acids, magnesium combined with vitamin E, and vitamin D reported greater reductions in wound length, depth, and width than placebo, with differences in length of roughly 0.6 to 1.0 cm. The review authors cautioned that these studies had a high risk of bias, small samples, wide confidence intervals, and poor reporting of baseline nutritional status. They also measured individual wound dimensions rather than total area or complete closure. The review concluded that the evidence does not establish whether any of these interventions improve DFU healing.
Vitamin D: Strong Association, Uncertain Causation
Vitamin D has attracted particular interest. An umbrella review in Frontiers in Nutrition (Liu and colleagues, 2024) synthesized seven meta-analyses, covering twenty unique randomized trials, on vitamin D and DFU. Most of the included meta-analyses found lower serum 25-hydroxyvitamin D in people with DFU than in people with diabetes but no ulcer, with differences ranging from about 5 to 13 ng/mL, and higher odds of severe deficiency among those with ulcers (odds ratios of roughly 2.3 to 3.6).
The only interventional meta-analysis, which pooled supplementation trials against placebo, reported a smaller ulcer area in the supplemented groups. However, the umbrella review rated the methodological quality of the included reviews as low or critically low, and the underlying trials had inadequate blinding and substantial post-randomization dropout. The authors stated that causal conclusions cannot be drawn and that larger, long-term randomized trials are needed. Deficiency is common in people with DFU, but whether correcting it speeds healing remains unproven.
Interpreting the Evidence
Two points help place these findings in context. First, absence of proof is not proof of absence: small trials with heterogeneous populations, brief follow-up, and non-standard outcomes could easily miss a real benefit, particularly in patients who are truly malnourished. Supplementing a well-nourished patient is unlikely to accelerate healing, whereas correcting a documented deficit may matter. Second, nutrition does not substitute for the established determinants of healing, namely offloading, perfusion assessment, infection control, and debridement, as outlined in the International Working Group on the Diabetic Foot (IWGDF) 2023 guidelines on ulcer healing.
Key Takeaways
Nutritional screening with a validated tool is recommended in current guidance and is low-risk. Evidence that specific supplements, including amino acid blends, zinc, magnesium, omega-3 fatty acids, or vitamin D, improve DFU closure is of very low certainty. Low vitamin D is strongly associated with DFU, but benefit from supplementation has not been confirmed in high-quality trials. Adequate energy, protein, and glycaemic management remain reasonable goals alongside standard wound care while better evidence is generated.
References
- Moore ZEH, Corcoran MA, Patton D. Nutritional interventions for treating foot ulcers in people with diabetes. Cochrane Database of Systematic Reviews. 2020;(7):CD011378.
- Liu L, Zhang F, Jamali M, et al. The role of vitamin D in diabetic foot ulcer: an umbrella review of meta-analyses. Frontiers in Nutrition. 2024;11.
- Armstrong DG, et al. Nutrition Interventions in Adults with Diabetic Foot Ulcers. American Limb Preservation Society guidance. 2022.
- Sonko I. Nutritional assessment screening tools on diabetic foot ulcer healing: a systematic review. Southeast Asia Nursing Research. 2023;5(3):24-27.
- Chen P, Vilorio NC, Dhatariya K, et al. Guidelines on interventions to enhance healing of foot ulcers in people with diabetes (IWGDF 2023 update). Diabetes/Metabolism Research and Reviews. 2024;40(3):e3644.
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