The efficacy of soy isoflavones combined with soy protein on serum concentration of interleukin-6 and tumour necrosis factor-α among post-menopausal women? A systematic review and meta-analysis of randomized controlled trials

A systematic review and dose-response meta-analysis of the effect of selenium supplementation on serum concentration of C-reactive protein

BACKGROUND

Despite conducting new studies on the potential effect of selenium in reducing inflammation; results held contradictory weights and turns into an intriguing area of research. Concerns have been raised on this matter on hand to reach conclusive/consistent results. Therefore, this study seeks to address this scientific gap by assessing randomized controlled trials (RCTs) investigating the effect of selenium intake on C-reactive protein (CRP).

METHOD AND MATERIALS

To find all the relevant English-language RCTs, databases including SCOPUS, Web of Science, Clinical Trials.gov, PubMed, and Cochrane Library were searched with no time limit (up to June 2022). Based on the mean changes for both comparison and intervention groups, the effect sizes were calculated. Further, DerSimonian and Laird random-effects model was performed to determine the summary of overall effects and their heterogeneity.

RESULTS

Fifteen studies were selected for systematic review and thirteen studies were known to be eligible for meta-analysis. Meta-analysis results indicated a significant effect in serum CRP concentrations compared to the control group (weighted mean difference (WMD)= -0.22 mg/L 95 % confidence interval (CI): - 0.39, - 0.04; p = 0.014).

CONCLUSION

In conclusion, our study confirms the downward effect of selenium on the serum concentration of CRP. On a wider level, further research is also needed to assess the selenium effect on other inflammatory mediators.

Soy Protein Containing Isoflavones Improves Facial Signs of Photoaging and Skin Hydration in Postmenopausal Women: Results of a Prospective Randomized Double-Blind Controlled Trial

Preliminary findings from multiple studies indicate that dietary intake of soy-derived isoflavones exert beneficial effects on the skin including defense against oxidant damage, stimulation of collagen synthesis, and increased hydration. This study aims to investigate how oral supplementation of a soy protein isolate with added isoflavones (SPII) affects components of photoaging such as facial wrinkles and dyspigmentation, and skin biophysical measures such as skin hydration and sebum excretion in postmenopausal women. This 6-month prospective, randomized double-blind controlled study was conducted on 44 postmenopausal women with Fitzpatrick skin types I, II, and III who were randomized to receive either casein protein or SPII. A high-resolution facial photography system was used to measure wrinkle severity and pigmentation at 0, 8, 16, and 24 weeks. Skin biophysical measurements included skin hydration and sebum production. The average wrinkle severity was decreased in the SPII intervention group at week 16 and week 24 by 5.9% and 7.1%, respectively, compared to the baseline. Compared to the casein group, average wrinkle severity was significantly decreased at week 16 (p < 0.05) and week 24 (p < 0.0001). Facial pigment intensity was decreased by -2.5% (p < 0.05) at week 24, whereas there was no significant change in the casein group. Compared to baseline, skin hydration in the SPII group was significantly increased by 39% and 68% on the left and right cheeks (p < 0.05), respectively, at 24 weeks. There were no significant differences in sebum production. Dietary soy protein supplementation with isoflavones may improve skin photoaging, including wrinkles and dyspigmentation, and increase skin hydration in postmenopausal women with Fitzpatrick skin types I, II, and III.

Effect of the Fermented Soy Q-CAN® Product on Biomarkers of Inflammation and Oxidation in Adults with Cardiovascular Risk, and Canonical Correlations between the Inflammation Biomarkers and Blood Lipids

Systemic low-grade inflammation plays a key role in the development of cardiovascular disease (CVD) but the process may be modulated by consuming fermented soy foods. Here, we aim to evaluate the effect of a fermented soy powder Q-CAN^® on inflammatory and oxidation biomarkers in subjects with cardiovascular risk. In a randomized crossover trial, 27 adults (mean age ± SD, 51.6 ± 13.5 y) with a mean BMI ± SD of 32.3 ± 7.3 kg/m² consumed 25 g daily of the fermented soy powder or an isoenergic control powder of sprouted brown rice for 12 weeks each. Between-treatment results showed a 12% increase in interleukin-1 receptor agonist (IL-1Ra) in the treatment group, whereas within-treatment results showed 23% and 7% increases in interleukin-6 (IL-6) and total antioxidant status (TAS), respectively. The first canonical correlation coefficient (r = 0.72) between inflammation markers and blood lipids indicated a positive association between high-sensitivity C-reactive protein (hsCRP) and IL-1Ra with LDL-C and a negative association with HDL-C that explained 62% of the variability in the biomarkers. These outcomes suggest that blood lipids and inflammatory markers are highly correlated and that ingestion of the fermented soy powder Q-CAN^® may increase IL-1Ra, IL-6, and TAS in individuals with CVD risk factors.

Relationship of Inflammatory Markers and Metabolic Syndrome in Postmenopausal Women

The increased deposition of visceral fat in the postmenopause period increases the production of inflammatory cytokines and the release of tumor necrosis factor- α (TNF-α), interleukin-6 (IL-6), and decrease in IL-10. This study investigated the relationship between inflammatory biomarkers and metabolic syndrome (MS) in postmenopausal women considering different diagnostic criteria. We conducted a cross-sectional observational study based on STROBE. Data were collected regarding the diagnostic criteria for MS (International Diabetes Federation; NCEP (International Diabetes Federation (IDF), National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP-III), and Harmonized criteria), body composition, comorbidities, time without menstruation, values of IL-6, IL-10, and TNF-α. ANOVA, Kruskal-Wallis, Levene tests, ROC, and odds ratio were performed to analyze the data. The results showed no significant difference between the methods and no interaction between the method and the presence of MS. However, for the values of WC, body fat percentage, TNF-α, and IL-10/TNF-α ratio, a significant effect of MS was observed. In subjects with MS, lower values of body fat percentage and TNF-α and higher values of the IL-10/TNF-α ratio were also observed. The higher IL-10/TNF-α ratio in the MS group is related to the greater anti-inflationary action of IL-10. The IL-10/TNF-α ratio showed significant accuracy to discriminate patients with MS according to the NCEP-ATP III criteria.