Table 3.

Impact of vitamin D supplementation on acute asthma attacks

Study reference	Sample size (VitD/placebo)	Acute asthma attacks (VitD)	Acute asthma attacks (placebo)	Odds ratio (95% CI)
Tachimoto 2016 [36]	55/36	Data not mentioned	Data not mentioned	0.41 [0.06, 2.59]
Jensen 2016 [35]	12/12	Fewer	More	2.10 [0.37, 11.58]
Urashima 2010 [37]	49/50	Reduced	Increased	0.17 [0.03, 0.76]
Majak 2011 [28]	23/25	Reduced	Increased	0.24 [0.06, 0.91]
Yadav 2014 [32]	52/52	Reduced	Increased	0.25 [0.12, 0.61]
Castro 2014 [31]	202/209	Reduced	Increased	0.71 [0.41, 1.21]
Martineau 2015 [34]	124/126	Reduced	Increased	1.22 [0.42, 2.05]
Total (95% CI)	498/501			0.54 [0.29, 0.98]