Cumulative Meta-Analysis of the Soy Effect Over Time
Research snapshot:
2019 meta-analysis finds soy protein significantly reduces LDL cholesterol levels over time.
2019 |
Meta-analysis |
Soy protein |
LDL cholesterol reduction |
Overview.
A cumulative meta-analysis of 46 studies confirms that soy protein continues to have a significant, albeit modest, effect in reducing serum LDL cholesterol levels, supporting its inclusion in cholesterol-lowering diets.
Background.
A team of researchers associated with the University of Toronto, St. Michael's Hospital, and other institutions, published this study in the Journal of the American Heart Association. The study was led by David J.A. Jenkins and included contributions from Sonia Blanco Mejia, Laura Chiavaroli, Effie Viguiliouk, Siying S. Li, Cyril W.C. Kendall, Vladmir Vuksan, and John L. Sievenpiper.
Objectives.
The study aimed to assess whether the cholesterol-lowering effect of soy protein, as established by the 1999 FDA heart health claim, had lost significance over time. The researchers sought to determine if the cumulative evidence from 46 trials identified by the FDA still supported the health claim.
Study design.
This was a cumulative meta-analysis of 46 randomized controlled trials selected by the FDA. The trials involved 2607 participants, with a median age of 55 years, and 37% of the participants were men. The median soy protein dose was 25 g/day, and the median follow-up was 6 weeks. The study used a random-effects model and tracked the progression of evidence over time to pinpoint any changes in the effect of soy protein on total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C).
Results.
The cumulative meta-analysis showed that soy protein intake resulted in significant reductions in both TC and LDL-C. The mean reduction in LDL-C was -6.3 mg/dL in 1999 and remained between -4.2 and -6.7 mg/dL over the following 14 years. Similar patterns were observed for TC, with a significant reduction of -4.5 mg/dL in 1999 and continued significance over the subsequent years.
Conclusions.
The study concluded that soy protein continues to have a modest but significant cholesterol-lowering effect, supporting the maintenance of the FDA's heart health claim. The researchers emphasized that combining soy with other cholesterol-lowering foods could produce clinically meaningful reductions in LDL-C.
Original paper.
Jenkins DJA, Blanco Mejia S, Chiavaroli L, et al. Cumulative Meta-Analysis of the Soy Effect Over Time. J Am Heart Assoc. 2019;8:e012458. DOI: 10.1161/JAHA.119.012458
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