Effects of soy protein supplementation on leptin
concentration
As outlined in Figure 2 , our preliminary analysis indicated
that soy and soy products consumption have no significant difference in
serum leptin concentration (WMD = 0.12; 95% CI: -3.26, 3.51; P= 0.921)
Also, significant heterogeneity was observed among studies (Cochran’s Q
test = 109.59, P= 0.000, I2 = 88.1 %). Subgroup
analysis was conducted to check if the effect of soy protein
supplementation on serum leptin is different according to gender of
participant, baseline BMI, dose of soy protein, duration of studies,
supplementation type and study design (Table 3 ). This analysis
revealed that the pooled effect of soy protein supplementation on leptin
concentration was influenced by dose of soy protein (≤20 g/day
versus>20 g/day), in this way that, a significant increase
in leptin concentration was found in studies that used more than 20
g/day soy protein (WMD = 4.405; 95% CI: 0.578, 8.232; P= 0.024).
Subgroup analysis didn’t show any significant effect of soy protein
supplementation on leptin concentration in other subgroups.