madman
Super Moderator
Abstract
Background
Protein supplements are important to maintain optimum health and physical performance, particularly in athletes and active individuals to repair and rebuild their skeletal muscles and connective tissues. Soy protein (SP) has gained popularity in recent years as an alternative to animal proteins.
Objectives
This systematic review evaluates the evidence from randomized controlled clinical trials of the effects of SP supplementation in active individuals and athletes in terms of muscle adaptations, metabolic and antioxidant status, hormonal response, and exercise performance. It also explores the differences in SP supplementation effects in comparison to whey protein.
Methods
A systematic search was conducted in PubMed, Embase, and Web of Science, as well as a manual search in Google Scholar and EBSCO, on 27 June 2023. Randomized controlled trials that evaluated the applications of SPs supplementation on sports and athletic-related outcomes that are linked with exercise performance, adaptations, and biomarkers in athletes and physically active adolescents and young adults (14 to 39 years old) were included, otherwise, studies were excluded. The risk of bias was assessed according to Cochrane’s revised risk of bias tool.
Results
A total of 19 eligible original research articles were included that investigated the effect of SP supplementation on muscle adaptations (n=9), metabolic and antioxidant status (n=6), hormonal response (n=6), and exercise performance(n=6). Some studies investigated more than one effect. SP was found to provide identical increases in lean mass compared to whey in some studies. SP consumption promoted the reduction of exercise-induced metabolic/blood circulating biomarkers such as triglycerides, uric acid, and lactate. Better antioxidant capacity against oxidative stress has been seen with respect to whey protein in long-term studies. Some studies reported testosterone and cortisol fluctuations related to SP; however, more research is required. All studies on SP and endurance performance suggested the potential beneficial effects of SPsupplementation (10–53.3 g) on exercise performance by improving high-intensity and high-speed running performance, enhancing maximal cardiac output, delaying fatigue, and improving isometric muscle strength, improving endurance in recreational cyclists, increasing running velocity and decreasing accumulated lactate levels; however, studies determining the efficacy of soy protein on VO2max provided conflicted results.
Conclusion
It is possible to recommend SP to athletes and active individuals in place of conventional protein supplements by assessing their dosage and effectiveness in relation to different types of training. SP may enhance lean mass compared with other protein sources, enhance the antioxidant status, and reduce oxidative stress. SP supplementation had an inconsistent effect on testosterone and cortisol levels. SP supplementation may be beneficial, especially after muscle damage,high-intensity/high-speed, or repeated bouts of strenuous exercise.
5 Conclusions and Future Perspectives
This systematic review reveals that SPs may increase lean mass during resistance training similarly to whey protein; nevertheless, certain studies indicate that milk and whey proteins may be preferable for increasing lean mass at a faster rate. When compared with whey protein, maltodextrin, or placebo, the evidence suggests that long-term SP supplementation along with exercise training may boost antioxidant defense and limit lipid peroxidation. In terms of its effects on hormonal response, there are often contradictory findings regarding the effect of SP supplementation on testosterone and cortisol levels, and on biomarkers associated with muscle androgenic or estrogenic signaling. While soy protein supplementation in athletes/active individuals is promising, the studies included in the review have several limitations, such as heterogeneity of interventions, exercises performed, exercise intensities, and frequency and timing of protein intake. Therefore, future studies adjusting total daily protein intake as ~ 1.6 g/protein, including both leucine-matched and dose-matched protein administration, and≥12 weeks of training protocols along with the supplementation are needed. Finally, more research is needed to elucidate the body compositional and exercise performance effects of SPs compared to other proteins in different states of energy balance (i.e. sustained hypo- and hypercaloric conditions).
Background
Protein supplements are important to maintain optimum health and physical performance, particularly in athletes and active individuals to repair and rebuild their skeletal muscles and connective tissues. Soy protein (SP) has gained popularity in recent years as an alternative to animal proteins.
Objectives
This systematic review evaluates the evidence from randomized controlled clinical trials of the effects of SP supplementation in active individuals and athletes in terms of muscle adaptations, metabolic and antioxidant status, hormonal response, and exercise performance. It also explores the differences in SP supplementation effects in comparison to whey protein.
Methods
A systematic search was conducted in PubMed, Embase, and Web of Science, as well as a manual search in Google Scholar and EBSCO, on 27 June 2023. Randomized controlled trials that evaluated the applications of SPs supplementation on sports and athletic-related outcomes that are linked with exercise performance, adaptations, and biomarkers in athletes and physically active adolescents and young adults (14 to 39 years old) were included, otherwise, studies were excluded. The risk of bias was assessed according to Cochrane’s revised risk of bias tool.
Results
A total of 19 eligible original research articles were included that investigated the effect of SP supplementation on muscle adaptations (n=9), metabolic and antioxidant status (n=6), hormonal response (n=6), and exercise performance(n=6). Some studies investigated more than one effect. SP was found to provide identical increases in lean mass compared to whey in some studies. SP consumption promoted the reduction of exercise-induced metabolic/blood circulating biomarkers such as triglycerides, uric acid, and lactate. Better antioxidant capacity against oxidative stress has been seen with respect to whey protein in long-term studies. Some studies reported testosterone and cortisol fluctuations related to SP; however, more research is required. All studies on SP and endurance performance suggested the potential beneficial effects of SPsupplementation (10–53.3 g) on exercise performance by improving high-intensity and high-speed running performance, enhancing maximal cardiac output, delaying fatigue, and improving isometric muscle strength, improving endurance in recreational cyclists, increasing running velocity and decreasing accumulated lactate levels; however, studies determining the efficacy of soy protein on VO2max provided conflicted results.
Conclusion
It is possible to recommend SP to athletes and active individuals in place of conventional protein supplements by assessing their dosage and effectiveness in relation to different types of training. SP may enhance lean mass compared with other protein sources, enhance the antioxidant status, and reduce oxidative stress. SP supplementation had an inconsistent effect on testosterone and cortisol levels. SP supplementation may be beneficial, especially after muscle damage,high-intensity/high-speed, or repeated bouts of strenuous exercise.
5 Conclusions and Future Perspectives
This systematic review reveals that SPs may increase lean mass during resistance training similarly to whey protein; nevertheless, certain studies indicate that milk and whey proteins may be preferable for increasing lean mass at a faster rate. When compared with whey protein, maltodextrin, or placebo, the evidence suggests that long-term SP supplementation along with exercise training may boost antioxidant defense and limit lipid peroxidation. In terms of its effects on hormonal response, there are often contradictory findings regarding the effect of SP supplementation on testosterone and cortisol levels, and on biomarkers associated with muscle androgenic or estrogenic signaling. While soy protein supplementation in athletes/active individuals is promising, the studies included in the review have several limitations, such as heterogeneity of interventions, exercises performed, exercise intensities, and frequency and timing of protein intake. Therefore, future studies adjusting total daily protein intake as ~ 1.6 g/protein, including both leucine-matched and dose-matched protein administration, and≥12 weeks of training protocols along with the supplementation are needed. Finally, more research is needed to elucidate the body compositional and exercise performance effects of SPs compared to other proteins in different states of energy balance (i.e. sustained hypo- and hypercaloric conditions).
