Men's Health Research

Zinc is a vital trace element for normal function of the living system. In male, zinc is involved in various biological processes, an important function of which is as a balancer of hormones such as testosterone. For this purpose, studies related to the influence of zinc on serum testosterone were selected and summarized, including the effect of dietary zinc deficiency and zinc supplementation on testosterone concentrations. After preliminary searching of papers on databases, 38 papers including 8 clinical and 30 animal studies were included in this review. We concluded that zinc deficiency reduces testosterone levels and zinc supplementation improves testosterone levels. Furthermore, the effect degree of zinc on serum testosterone may vary depending on basal zinc and testosterone levels, zinc dosage form, elementary zinc dose, and duration. In conclusion, serum zinc was positively correlated with total testosterone, and moderate supplementation plays an important role in improving androgen.

The aim of this study was to conduct a systematic review of the literature of randomized controlled trials on the effect of testosterone (T) supplementation compared to the placebo group or lower dose on sarcopenic components (muscle mass, strength and physical performance) in middle-aged and elderly men. Major electronic databases were searched for articles published on or before December 2019. Studies including individuals with age ≥ 40 years and which described the effect of T supplementation on sarcopenic components were found eligible (11 studies). Outcomes were calculated as the difference in means between the experimental and control/placebo groups, and data were presented as effect size with 95% confidence limits (95%CI). The meta-analysis was performed using a random effects model. Regarding lean body mass (LBM), eight studies evaluated the effect of T supplementation on this outcome, of these, seven reported gains after the intervention period. Our meta-analysis showed a beneficial effect on LBM of 2.54 kg (95% CI, 1.27 to 3.80) (p < 0.001). In muscle strength (MS), seven included studies evaluated the handgrip strength (HGS) and just one reported gain after the intervention period, but the meta-analysis showed an increase for HGS of 1.58 kgf (95%CI, 0.17 to 3.0) (p = 0.03). The second outcome for MS was leg strength (LS), where nine studies were included and five demonstrated gains in this parameter after the intervention period. In the meta-analysis, two out of three tests showed an effect on LS: T supplementation increase the leg press strength in 91.23 N (95%CI, 0.23 to 182.22) (p = 0.05) and leg extension in 144.10 N (95%CI, 44.21 to 244.00) (p < 0.01). In physical performance, four studies evaluated this outcome, with three of them showing positive effects in this parameter. In the meta-analysis, only two studies that reported the same assessment test (Physical Performance Test) were included, but no effect of T supplementation on this parameter was found. It can be concluded that T supplementation influences sarcopenic components in middle-aged and older men, because is associated with increased in muscle mass and strength in addition to physical performance.

[BACKGROUND AND AIMS] Testosterone supplementation therapy (TST) is a longstanding treatment for hypogonadal men with type 2 diabetes mellitus (T2DM), even though the benefits of TST are variable among trials. This meta-analysis was done to determine the specific role of TST in hypogonadal men with T2DM. [METHODS] PubMed, Embase, and Google Scholar were queried to discover eligible randomized controlled trials (RCTs) and observational studies. To quantify the specific effects of TST, we estimated pooled mean differences (MDs) and relative risks with 95% confidence intervals (CIs). [RESULTS] Our meta-analysis included 1596 hypogonadal T2DM subjects from 12 randomized controlled trials and one observational study. TST can significantly enhance glycemic control compared to placebo by decreasing homeostatic model assessment of insulin resistance (WMD = -1.55 [-2.65, -0.45]; p = 0.26; I2 = 20.2%), fasting glucose (WMD = -0.35 [-0.79, 0.10]; p = 0.07; I2 = 69.7%), fasting insulin (WMD = -2.88 [-6.12, 0.36]; p = In addition, TST can decrease cholesterol (WMD = -0.28 [-0.47, -0.09] p = 0.0008; I2 = 91%) and triglyceride (WMD = -0.23 [-0.43, -0.03] p = 0.03; I2 = 79.2%). Furthermore, Testosterone therapy is related to a significant rise in total testosterone levels (WMD = 5.08 [2.90, 7.26] p = 0.0002; I2 = 92.9%). Pooling of free testosterone levels indicated a larger increase in the patients who got TST than placebo (WMD = 81.21 [23.87, 138.54] p = 0.07; I2 = 70%). [CONCLUSION] Our findings suggested that TST can enhance glycemic control and hormone levels and reduce total cholesterol, triglyceride, LDL cholesterol whereas increase HDL cholesterol in hypogonadal T2DM patients. Therefore, in these patients, we propose TST alongside anti-diabetic treatment.

Tribulus terrestris is a medicinal herb purported to enhance reproductive function, particularly in instances of erectile dysfunction (ED). This study aims to assess the effectiveness and safety of administering Tribulus terrestris to patients with ED. We performed a systematic literature review in the Cochrane Library, Medline, Scopus, and Europe PMC databases utilizing particular keywords. The primary endpoint in this study is International Index of Erectile Function, that may be in abridged form (IIEF-5) or full form (IIEF-15). The outcomes of continuous variables were aggregated into the mean difference (MD) with corresponding 95% confidence intervals (95% CI) utilizing random-effects models. Eight studies were selected for inclusion. After the intervention with Tribulus terrestris, the IIEF-5 [MD 4.21, p < 0.00001] and IIEF-15 scores [MD 15.88, p = 0.0004] were markedly elevated compared to their pre-supplementation levels, as per our comprehensive analysis. Additionally, on both the IIEF-5 [MD 3.23 (95%CI 1.89, 4.58), p < 0.00001] and IIEF-15 [MD 14.44 (95%CI 5.75, 23.14), p = 0.001], Tribulus terrestris outperformed placebo. However, the two groups were not significantly different in terms of total testosterone levels. We observed no difference in the incidence of adverse events between Tribulus terrestris and placebo. Tribulus terrestris supplementation may offer benefits in improving erectile function among patients with ED with a relatively good safety profile.

[BACKGROUND] An increasing body of literature suggests a positive, neuroprotective effect for testosterone on cognition in older men. However, randomized clinical trials (RCTs) examining the effects of testosterone supplementation (TS) on cognitive function have been inconclusive. [OBJECTIVE] To investigate the potential for TS to prevent cognitive decline in otherwise cognitively healthy older men, by examining the differential effects of TS on cognitively healthy older men in RCTs. [METHODS] Comprehensive search of electronic databases, conference proceedings, and grey literature from 1990 to 2018 was performed to identify RCTs examining the effects of TS on cognition before and after supplementation, in cognitively healthy individuals. [RESULTS] A final sample of 14 eligible RCTs met inclusion criteria. Using pooled random effects expressed as Hedge's g, comparison of placebo versus treatment groups pre- and postsupplementation showed improvements in the treatment group in executive function (g (11) = 0.14, 95% confidence interval [CI]: 0.03-0.26, z = 0.56, p = 0.011). However, it was noted that two studies in our sample did not report a significant increase in mean serum total testosterone (TT) levels in the treatment group after supplementation. Following exclusion of these studies, analysis indicated improvement in the treatment group for the overall cognitive composite (g (11) = 0.18, 95% CI: 0.02-0.33, z = 2.18), psychomotor speed (g (3) = 0.22, 95% CI: 0.01-0.43, z = 2.07) and executive function (g (9) = 0.15, 95% CI: 0.03-0.28, z = 2.35). No significant differences were noted for the global cognition, attention, verbal memory, visuospatial ability or visuospatial memory domains. [CONCLUSION] Overall, our findings support the potential for TS as a preventative measure against cognitive decline, although the effect sizes were small. These findings warrant further observational studies and clinical trials of good methodological quality, to elucidate the effect of TS on cognition.

Testosterone supplementation may be effective for the treatment of hypogonadism in men with type 2 diabetes mellitus (T2DM), but the evidence from randomized controlled trials (RCTs) is inconclusive. We aimed to systematically summarize results from intervention studies and assess the effects of testosterone supplementation therapy (TST) on lipid metabolism in RCTs of hypogonadal men with T2DM by meta-analysis. PubMed, Embase, and Cochrane Library databases were searched for studies reporting the effect of TST on lipid metabolism in hypogonadal men with T2DM until December 31, 2016. Seven RCTs from 252 trials, enrolling a total of 612 patients in the experimental and control groups with a mean age of 58.5 years, were included in this study. The pooled results of the meta-analysis demonstrated that TST significantly decreased TC and TG levels in hypogonadal men with T2DM compared with the control group, with mean differences (MDs) of -6.44 (95% CI: -11.82 to -1.06; I