Clinical and metabolic response to soy administration in older women with metabolic syndrome: a randomized controlled trial

Abstract

Background There are many studies on the health effects of soy, only a few describe the effects of the simultaneous use of two types of soy on multiple components of metabolic syndrome (MetS). The present study was designed to determine the effects of roasted soy-nut and textured soy protein (TSP) intake on clinical and metabolic status of older women with MetS borderline parameters. Method This randomized, single-blind, controlled clinical trial included 75 women ≥ 60 years old with a diagnosis of MetS based on ATP III criteria. The participants were randomly allocated into three groups of 25 people; soy-nut, TSP and control groups for 12 week. Fasting blood samples were taken at the beginning and end of the trial to compare the metabolic responses. All participants provided three dietary records and physical activity records during the intervention. We used the Kolmogorov–Smirnov, ANOVA, ANCOVA, paired-t test, and the Generalized Linear Model (GLM) repeated measures analysis. Results Dietary intake and physical activity of the participants in two groups were not significantly different. After 12 weeks of intervention the participants who received soy-nut had a significant decrease in total cholesterol (TC) (p < 0.001), low density lipoprotein, very low density lipoprotein, apolipoprotein B100, fasting blood glucose, insulin (p < 0.05), HOMA-IR, malondialdehyde (MDA) (p < 0.01) level. Morever, a significant increase in total antioxidant capacity (TAC) (p < 0.01) level compared with the control group. At the same time, the TSP brought significant decrease only in TC, insulin, MDA (p < 0.05) level and a significant increase in total TAC (p < 0.05) level. We did not find any significant effect in intervention groups, on apolipoprotein AI, triglyceride (TG), high density lipoprotein (HDL-C), TG/HDL, C-reactive protein and fibrinogen levels after intervention. Conclusion Short-term intakes of roasted soy-nut and TSP have shown to improve the lipid profiles, markers of glucose intolerance and oxidative stress; although the roasted soy-nut was more effective than TSP. Therefore, a moderate daily intake of roasted soy-nut as snacks or TSP as a meal complement by individuals with borderline parameters of MetS can be a safe and a practical modality to avoid the progression of the disease as well as to limit the side effects of drug intake. Trial registration MUBABOL.REC.1388.1 Electronic supplementary material The online version of this article (10.1186/s13098-019-0441-y) contains supplementary material, which is available to authorized users.

The Antioxidant Role of Soy and Soy Foods in Human Health

“…Results on lipid oxidation markers following intervention with isolated soy proteins showed improvement [ 29 , 30 , 54 , 57 ], as well as partial results [ 59 ], pejorative [ 84 ], or no significant results [ 36 , 44 , 53 , 79 , 84 ]. About the oxidation of proteins, 1 work found no significant effects [ 44 ] and 1 showed partial effects [ 84 ].…”

“…About the oxidation of proteins, 1 work found no significant effects [ 44 ] and 1 showed partial effects [ 84 ]. The effects on total antioxidant capacity were ameliorative [ 29 , 30 , 84 ], partial [ 80 ], or not significant [ 53 ]. No intervention trials with isolated soy proteins used markers for the oxidation of nucleic acids or the evaluation of endogenous oxidation biomarkers.…”

“…Among the 5 manuscripts that used soy nuts, 3 trials showed an improvement on lipid oxidation markers [ 29 , 30 , 73 ] and 3 trials showed an improvement effect on the total oxidation capacity [ 29 , 30 , 76 ]. No selected manuscript showed negative effects on any marker, mixed-effects, or no significant effects.…”

“…Even if the intake of phytoestrogens in the soy nuts arm was slightly greater, a beneficial effect of the food matrix is not excluded. Even in the work of Bakhtiari and colleagues [ 30 ], there were no differences in the effect on the oxidation markers between the soy protein arm and the soy nut arm, although the latter had higher isoflavones levels, as highlighted in the work of Azabakht and colleagues [ 29 ]. In the work of Sen and colleagues already cited, various soy-based foods, including soy nuts, were used, but the choice of the types of foods was a participants’ option, with a total daily intake of 50 mg of isoflavones [ 77 ].…”

The effect of soy isoflavones and soy isoflavones plus soy protein on serum concentration of C-reactive protein among postmenopausal women: A systematic review and meta-analysis of randomized controlled trials

“…Previous information regarding soy consumption and inflammatory markers among postmenopausal women are far from conclusive. Some randomized clinical trials support the effectiveness of soy food consumption on proinflammatory cytokine reduction (25)(26)(27)(28)(29), while others do not (30)(31)(32)(33)(34)(35)(36). A meta-analysis in 2011 with 14 trials examined soy isoflavones effect on serum concentration of CRP among postmenopausal women and their results proposed non-significant effect of soy isoflavones on CRP (37).…”