Table 2.
Subgroup analysis of the effects of isoflavones on serum total cholesterol. Isoflavones were shown to have significant benefits when given in the form of ISP or soy protein capsule. Regardless the forms of prescription, isoflavones decreased serum total cholesterol among normolipidemic but not hyperlipidemic subjects.
| Subgroup outcome | No. of comparisons | No. of subjects || | Treatment effect on TC (mmol/L) ¶ | Heterogeneity p-value § |
| Form of intervention †: | ||||
| a.) isoflavones tablets | 12 [8-10,12,13,16-18,20,21] | 482 | 0.01 (-0.17, 0.18) | 1.00 |
| b.) ISP(+) | 8 [14,15,22,23] | 229 | -0.11 (-0.21, -0.01)* | 0.34 |
| c.) soy protein capsule | 1 [11] | 78 | -0.69 (-1.19, -0.19)* | NA |
| d.) soy biscuit | 1 [7] | 20 | -0.05 (-0.47, 0.37) | NA |
| e.) soy burger | 1 [19] | 44 | 0.09 (-0.38, 0.56) | NA |
| f.) Overall | 21 [7-23] | 853 | -0.09 (-0.18, -0.01)* | 0.77 |
| Isoflavones mixture ‡: | ||||
| G&D&B&F | 5 [12,13,17,18] | 214 | -0.06 (-0.34, 0.21) | 0.96 |
| G&D | 6 [9-11,16,19,22] | 285 | -0.22 (-0.41, -0.03)* | 0.06 |
| G | 1 [21] | 60 | 0.10 (-0.35, 0.55) | NA |
| Isoflavones intake (mg per day): | ||||
| < 50 | 3 [8,13,17] | 132 | -0.12 (-0.54, 0.29) | 0.99 |
| 51–100 | 12 [8,10,12,14,15,17-23] | 484 | -0.10 (-0.21,0.01) | 0.74 |
| 101 – 150 | 4 [9,11,15,23] | 176 | -0.10 (-0.24, 0.05) | 0.09 |
| Design : | ||||
| parallel crossover | 9 [8-14,21] | 447 | -0.08 (-0.27, 0.10) | 0.48 |
| a.) no washout | 1 [22] | 56 | -0.43 (-0.73, -0.13)* | NA |
| b.) washout mentioned | 6 [15,19,20,23] | 208 | -0.07 (-0.17, 0.03) | 0.91 |
| Gender: | ||||
| male | 2 [7,22] | 76 | -0.30 (-0.54, -0.05)* | 0.15 |
| female | 17 [8-11,13-18,20,21,23] | 674 | -0.07 (-0.17, 0.02) | 0.89 |
| Treatment length: | ||||
| 2–10 weeks | 14[7,10,12,13,15-17,19,20,22,23] | 541 | -0.09 (-0.18, 0.00) | 0.84 |
| 11–20 weeks | 3 [11,14,18] | 155 | -0.22 (-0.52, 0.07) | 0.07 |
| 21–30 weeks | 4 [8,9,21] | 157 | 0.02 (-0.28, 0.31) | 0.96 |
| Menopausal status: | ||||
| pre-menopausal | 3 [15,18] | 80 | -0.06 (-0.17, 0.06) | 0.58 |
| peri-menopausal | 1 [11] | 78 | -0.69 (-1.19, -0.19)* | NA |
| post-menopausal | 13 [8-10,13,14,16,17,20,21,23] | 516 | -0.05 (-0.20, 0.10) | 1.00 |
| Subjects with: | ||||
| normolipidemia | 8 [11,12,15,18,19,21,22] | 377 | -0.11 (-0.21, -0.01)* | 0.08 |
| hyperlipidemia | 3 [7,9,14] | 105 | -0.05 (-0.36, 0.26) | 1.00 |
* statistically significant † 'ISP (+)' = isoflavone containing isolated soy protein; 'ISP (-)' = isoflavone depleting isolated soy protein ‡ 'G' = Genistein; 'D' = Daidzein; 'B' = Biochanin A; 'F' = Formononectin § NA = not applicable || Since subjects acted as their own controls in a crossover trial, the 'calculated' total number was thus doubled in a single pair comparison. ¶ 95% confidence interval in parenthesis