Tier 1: Clinical trials

Aquilani et al., 2009

Subacute stroke patients with low Zn²⁺ intake (< 6.6 mg/day)

Randomized, prospective, placebo-controlled, double-blind trial

Postinjury, Zn²⁺ supplementation at 10 mg/day or placebo

Compared to baseline values, all patients had significantly greater daily carbohydrate (p=0.03) and zinc intake (p < 0.001) and lower National Institute of Health Stroke Scale (NIHSS) scores (p < 0.001) at 30 days.

n^a=26

Compared to patients assigned to placebo, patients assigned to zinc supplementation had greater body weight (p=0.002), daily energy intake (p=0.02), protein intake (p=0.04), lipid intake (p=0.01), and zinc level (p < 0.001) at 30 days.

Zinc-treated patients also had higher level of serum albumin (p=0.001) and greater improvement in NIHSS score (p=0.04) than controls. And zinc intake was inversely correlated to NIHSS score (r^b=−0.46, p< 0.02).

No adverse effects of zinc were mentioned.

Young et al., 1996

Severe TBI

Randomized, prospective, double-blind, placebo-controlled trial

Postinjury, elemental zinc at standard level of 2.5 mg or supplementation at 12 mg for 15 days, then tablets of 22 mg elemental zinc or placebo for 3 months

Although there was no difference between the standard (2.5 mg) group and the supplemented (12 mg) group on serum zinc level, the supplemented group had significantly higher levels of zinc in urine at days 2 (p=0.0001) and 10 (p=0.01). But the significance disappeared at week 3.

n=68 TBI patients

Supplemented group also had higher mean serum pre-albumin level (p=0.003) and mean retinol-binding protein levels (p=0.01) at 3 weeks.

After adjusting for baseline value, supplemented group had higher mean Glasgow Coma Scale (GCS) score at day 28 (p=0.03) and mean motor GCS score at days 15 (p=0.005) and 21 (p=0.02), although there was no statistically significant difference in the raw GCS scores.

No adverse effects were mentioned.

Tier 2: Observational studies