Is soya consumption effective in improving lipid profile?
Date of publication of the systematic review: September 2015
Design
Systematic review of 35 randomized controlled trial (RCT).
Participants
2670 adults aged 28 to 83 were recruited (male%: 18%).
Intervention
Dietary soya products were consumed as intervention. Treatment duration ranged from 4 weeks to 1 year. The average intake of soya protein was 30g/d (range: 14 to 50g/d).
Comparator
Comparison: Dietary soya products versus milk protein or no intervention.
Major Outcomes
Outcome 1: Serum LDL-cholesterol concentrations as measured at the end of intervention;
Outcome 2: Triglycerides (TAG) as measured at the end of intervention;
Outcome 3: Total cholesterol concentrations as measured at the end of intervention;
Outcome 4: Serum HDL-cholesterol concentrations as measured at the end of intervention.
Settings
This study was performed in an outpatient setting.
Comparison    Dietary soya products versus milk protein or no intervention
Main Results
Compared to milk protein or no intervention, dietary soya products showed a significant reduction in serum LDL-cholesterol concentrations (pooled mean difference (pooled MD): -4.83, 95% CI: -7.34 to -2.31), TAG (pooled MD: -4.92, 95% CI: -7.79 to -2.04) and total cholesterol (pooled MD: -5.33, 95% CI: -8.35 to -2.30). Dietary soya products also resulted in a significant increase in serum HDL-cholesterol concentrations (pooled MD: 1.40, 95% CI: 0.58 to 2.23).
Comparison: Dietary soya products versus milk protein or no intervention
Outcomes (units) No. of studies (Total number of participants) Mean value/No. of participants Heterogeneity test (I2) Pooled MD (95% CI) p value Overall quality of evidence*
Intervention Comparator
1 (mg/dL) 35 (3366) not reported/1687 not reported/1679 97% -4.83 (-7.34 to -2.31) 0.0002 High
2 (mg/dL) 35 (2998) not reported/1502 not reported/1496 92% -4.92 (-7.79 to -2.04) 0.0008 High
3 (mg/dL) 35 (3247) not reported/1630 not reported/1617 99% -5.33 (-8.35 to -2.30) 0.0006 High
4 (mg/dL) 35 (3310) not reported/1659 not reported/1651 95% 1.40 (0.58 to 2.23) 0.0009 High
Keys: MD = mean difference, CI = confidence interval.
Comparison    Dietary soya products versus milk protein or no intervention
Main Results
Compared to milk protein or no intervention, dietary soya products showed a significant reduction in serum LDL-cholesterol concentrations (pooled mean difference (pooled MD): -4.83, 95% CI: -7.34 to -2.31), TAG (pooled MD: -4.92, 95% CI: -7.79 to -2.04) and total cholesterol (pooled MD: -5.33, 95% CI: -8.35 to -2.30). Dietary soya products also resulted in a significant increase in serum HDL-cholesterol concentrations (pooled MD: 1.40, 95% CI: 0.58 to 2.23).
Comparison: Dietary soya products versus milk protein or no intervention
Outcomes (units) 1 (mg/dL) 2 (mg/dL) 3 (mg/dL) 4 (mg/dL)
No. of studies (Total number of participants) 35 (3366) 35 (2998) 35 (3247) 35 (3310)
Mean value/No. of participants Intervention not reported/1687 not reported/1502 not reported/1630 not reported/1659
Comparator not reported/1679 not reported/1496 not reported/1617 not reported/1651
Pooled MD (95% CI) -4.83 (-7.34 to -2.31) -4.92 (-7.79 to -2.04) -5.33 (-8.35 to -2.30) 1.40 (0.58 to 2.23)
p value 0.0002 0.0008 0.0006 0.0009
Overall quality of evidence* High High High High
Keys: MD = mean difference, CI = confidence interval.
Conclusion
Benefits
Compared to milk protein or no intervention, dietary soya products significantly increased serum HDL concentration and lowered serum TAG, LDL and total cholesterol concentrations. For all outcomes, the overall quality of evidence is high. Further research is unlikely to have an important impact on our confidence in this estimate of effect.
Harms
The authors did not report details of adverse events.
Link to Original Article
https://www.ncbi.nlm.nih.gov/pubmed/26268987
The synopsis is based on the following article:
Tokede O.A., Onabanjo T.A., Yansane A., Gaziano J.M., Djoussé L. Soya products and serum lipids: a meta-analysis of randomised controlled trials. Br J Nutr. 2015 Sep 28;114(6):831-43.


* Interpretation of quality assessment results:
• Very low: Further research is most likely to have an important impact on our confidence in this estimate of effect.
• Low: Further research is likely to have an important impact on our confidence in this estimate of effect.
• Moderate: Further research is fairly likely to have an important impact on our confidence in this estimate of effect.
• High: Further research is unlikely to have an important impact on our confidence in this estimate of effect.
• Very high: Further research is most unlikely to have an important impact on our confidence in this estimate of effect.

Details of assessment method can be found at Chung VC, Wu XY, Ziea ET, Ng BF, Wong SY, Wu JC. Assessing internal validity of clinical evidence on effectiveness of CHinese and integrative medicine: Proposed framework for a CHinese and Integrative Medicine Evidence RAting System (CHIMERAS). European Journal of Integrative Medicine. 2015 Aug 31;7(4):332-41.