Wound Healing

Wound Healing

Wound repair runs through four overlapping phases, and nutritional status acts on each one differently. Hemostasis and inflammation come first, then proliferation, then remodeling that continues for months after a wound looks closed. Protein and zinc supply cell proliferation, ascorbate is required for collagen synthesis, retinoids govern epithelial differentiation, and iron carries the oxygen that every phase consumes. Chronic non-healing wounds affect 1 to 2 percent of the population in developed countries. Three ingredients carry an evidence grade here, one at Grade A and two at Grade D, across 25 studies and about 1,850 participants.

Zinc holds the Grade A rating on 18 studies and 1,500 participants, the only Grade A entry among the lower-traffic conditions on this site, and the reason is that its evidence comes from clinical populations with hard endpoints rather than from cosmetic proxies. Zinc is a cofactor for over 300 enzymes, including the matrix metalloproteinases that remodel the wound bed and the DNA and RNA polymerases that proliferating keratinocytes depend on. Older clinical reviews of nutrition in wound repair established the framework ^[1], and intervention studies of vitamin and mineral supplementation in patients with impaired repair have since tested it directly ^[2].

The most instructive single trial in this literature is not about zinc alone. A randomized trial of a nutritional formula enriched with arginine, zinc and antioxidants reported improved pressure ulcer healing in malnourished patients ^[3]. Its design is the point: it enrolled people with a deficit, used an objective endpoint, and combined nutrients that act on different phases. That is a substantially different question from whether supplementation accelerates repair in someone already nutritionally replete, and the two are frequently conflated.

Aloe vera and copper sit at Grade D on 4 studies and 200 participants and 3 studies and 150 participants respectively. Copper's rationale is enzymatic and specific, since lysyl oxidase requires it to crosslink collagen and elastin, but the human trial base is minimal. Aloe vera has an extensive traditional and preclinical literature and a thin controlled one. Broader reviews of nutrition in wound repair situate several plant-derived compounds, curcumin among them, in the same position of mechanistic plausibility with limited clinical demonstration ^[4].

The boundary of this evidence is deficiency. A Cochrane review of nutritional interventions for diabetic foot ulcers found the trial base insufficient to establish benefit in that population ^[5], which is a useful corrective: the strongest results in this field come from correcting a shortfall, and correcting a shortfall that does not exist has no mechanism by which to help.

Delayed closure is also a signal rather than a nutritional problem in isolation. Diabetes, vascular insufficiency, immunosuppression, smoking and corticosteroid use each impair repair through routes that supplementation does not address, and a wound that fails to close on a normal timeline, or shows spreading redness or discharge, requires clinical assessment rather than a nutritional adjustment.