Selenium status in the body and cardiovascular disease: a systematic review and meta-analysis

Figures & data

Figure 1. PRISMA flow diagram for screening and selection of articles on body selenium status and cardiovascular diseases incidence and mortality.

Table 1. Pooled RRs by study designs, sample type, disease, region of study conducted, and dose level of selenium in blood or toenail.

Outcome	Group variable	Subgroups	No. of doses	Pooled RR (95% CI)	I^2	p of I^2
Mortality	Study design	Case-control	1	0.45 (0.25–0.83)
		RCT	5	0.84 (0.41–1.73)	72.63%	0.003
		Cohort*	12	0.75 (0.64–0.87)	39.14%	0.106
	Sample type	Blood	18	0.71 (0.60–0.85)	54.32%	0.003
		Toenail	0
	Disease	CHD*	6	0.73 (0.59–0.91)	0.00%	0.575
		CVD	12	0.71 (0.55–0.91)	70.90%	0.000
	Region	Asia*	3	0.59 (0.45–0.79)	0.00%	0.553
		Europe*	8	0.55 (0.45–0.68)	0.00%	0.494
		US*	7	0.93 (0.82–1.05)	24.58%	0.241
	Dose level	Low (blood)*	2	0.46 (0.32–0.68)	0.00%	0.936
		Normal (blood)	16	0.75 (0.64–0.90)	49.95%	0.011
		Low (toenail)	0
		High (toenail)	0
Incidence	Study design	Case-control	13	0.86 (0.73–1.01)	47.76%	0.028
		RCT*	3	1.07 (0.81–1.42)	0.00%	0.587
		Cohort*	3	0.80 (0.70–0.92)	44.57%	0.165
	Sample type	Blood	11	0.84 (0.71–0.99)	29.82%	0.012
		Toenail*	8	0.89 (0.77–1.04)	10.68%	0.347
	Disease	CHD	16	0.83 (0.74–0.94)	18.23%	0.027
		CVD*	3	1.07 (0.81–1.42)	0.00%	0.587
	Region	Asia	4	0.52 (0.21–1.31)	97.23%	0.001
		Europe*	4	0.76 (0.61–0.94)	0.00%	0.650
		US*	11	1.02 (0.88–1.21)	0.00%	0.853
	Dose level	Low (blood)	1	0.92 (0.74–1.14)
		Normal (blood)	10	0.82 (0.66–1.02)	37.39%	0.010
		Low (toenail)*	3	0.79 (0.62–1.00)	0.00%	0.647
		High (toenail)*	5	0.97 (0.80–1.19)	23.70%	0.263

RCT: Randomized controlled trial; CVD, cardiovascular diseases; CHD, coronary heart disease

*Fixed-effects model was used.

Figure 2. Funnel plot with pseudo 95% confidence limit.

Figure 3. Pooled RRs of the highest concentrations compared to the lowest concentrations of selenium status in the body.

Figure 4. Association between log relative risk of incidence of cardiovascular diseases and increment in blood selenium concentration.

Table 2. Relative risk for mortality and incidence of cardiovascular diseases per unit* increase in selenium concentration.

	Sample type	Dose	RR (95% CI)	p
Mortality	Blood	18	0.93 (0.83–1.05)	0.240
	Toenail	0
Incidence	Blood	11	0.85 (0.76–0.94)	0.003
	Toenail	8	0.54 (0.09–3.28)	0.438

*Units are10 µg/L for blood sample and 1 µg/g for toenail sample, respectively.

Figure 5. Association between the relative risk of cardiovascular mortality and increment in blood selenium concentration.

Figure 6. Association between the relative risk of incidence of cardiovascular diseases and increment in toenail selenium concentration.