Table 3.

Zinc—summary of meta-analyses findings—main and subgroups

Micronutrient	Subgroup	Effect on occurrence of infection		Effect on duration of symptoms
		RR (95% CI)	P value	Percent diff (95% CI)	P value
Zinc	Main	1.06 (0.95 to 1.18)	0.31	−47 (−73 to –21)	0.0004
	Common cold outcome*	1.06 (0.95 to 1.18)	0.31	−59 (−84 to –35)	<0.0001
	Dose, mg/day
	≤13.3	Not est		−36 (−60 to –13)	0.79
	>13.3	Not est		−43 (−81 to –4)
	Form of supplement
	Gluconate	Not est		−251 (−396 to –106)	0.76
	Acetate	Not est		−206 (−462 to 30)
	Sex
	Female	1.31 (0.36 to 4.82)	0.74	−183 (−552 to 186)	0.87
	Male	0.81 (0.16 to 4.04)		−238 (−543 to 67)
	Continent
	Africa	NR	0.75	NR	0.023
	Asia	NR		NR
	Australia	NR		440 (−160 to 1040)
	Europe	0.89 (0.45 to 1.75)		NR
	North America	1.06 (0.95 to 1.19)		−268 (−384 to –153)
	South America	NR		NR
	Length of trial
	<2 weeks	1.06 (0.94 to 1.20)	0.92	Not est
	2 weeks to <3 months	1.05 (0.88 to 1.25)
	3 months to <1 years	1.02 (0.47 to 2.18)
	>1 years	NR

NR: Not relevant; that is, no primary studies that met the criteria. The mean age for all included studies was <40 years.

Not est: Not estimated; that is meta-analysis was not done.

*Sensitivity analysis.