The effect of dietary protein intake on factors associated with male infertility: A systematic literature review and meta-analysis of animal clinical trials in rats

Abstract

Background: Studies have shown that the amount of protein in the diet affects the hypothalamic-pituitary-testis axis and sub-optimal quantity reduces male fertility potential in both animals and humans. However, individual research reports on the factors associated with male infertility are collectively uncharacterized. Aim: We systematically reviewed, and meta-analysed animal (rats) studies on the effect of low protein diet on factors associated with male infertility. Methods: PubMed Central, EMBASE and Scopus databases were searched from inception to 30 March 2019 for the study concepts and related keywords in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol. Data on the outcome measures were extracted and pooled across trials using random-effects model and expressed as mean differences (MD) at a 95% confidence interval (CI). Results: Twelve trials identified from 3327 studies, met our inclusion criteria in the comparison of a low protein diet (2–10% protein) vs control protein diet (17–23% protein). The results showed that a low protein diet caused a significant reduction in the body weight ( P = 0.0001) testis weight ( P = 0.0001), seminal vesicle weight ( P = 0.0003), epididymis weight P = 0.02), serum testosterone ( P = 0.001) and follicle-stimulating hormone (FSH) concentrations ( P = 0.04) compared with the control treatments. No effect on luteinizing hormone (LH) plasma concentration ( P = 0.13) was observed. Conclusion: This study revealed that low protein diet caused significant reductions in body weight, testis, epididymis and seminal vesicle weights, serum testosterone and FSH concentration in rats. We infer that sub-optimal protein consumption reduces the gonadal and endocrine function, and consequently male infertility.

The Effects of Dietary Wheat and Corn Glutens on the Histopathological and Immunohistochemical Structure of the Ovarian Tissue and Serum and Ovarian Tissue LH and FSH Levels and Lipid Profiles in Rats

“…It is known that nutrition has an effect on FSH and LH levels [27]. Ajuogu and coauthors [28] has reported that low protein diet caused significant reductions in serum FSH concentration in rats. Similarly, in a previous study by Polkowska and coauthors [29] has raported that the low protein diet influenced the exerted an inhibitory effect on the synthesis and the release of LH in the pituitary gonadotrophs.…”

Diet and Male Fertility: The Impact of Nutrients and Antioxidants on Sperm Energetic Metabolism

“…Proteins are not energetic substrates for sperm cells [ 32 , 33 ]; moreover, a high-protein diet had no significant effect on glycemic control [ 83 ]. However, a low-protein diet has been considered a potential risk factor for male-factor infertility, causing a significant reduction in testis, epididymis, and seminal vesicle weights, as well as a decrease in serum testosterone [ 84 ]. Conversely, the reports on the effect of a high-protein diet present in the literature are contradictory [ 85 ].…”

Semen Analysis and Morphological Study of Two Subsequent Generations of Dietary Protein Deficient Sprague Dawley Rats

“…During the critical physiological state (pregnancy), most women run unconsciously into a state of undernutrition with unknown consequences in subsequent generations. Studies have shown that sub-optimal protein consumption reduces the gonadal and endocrine function, and consequently male infertility [9], but little is known about exposure at intrauterinecondition, and if persistence of this malnutrition could cause the same deleterious effects or there is an adaptive shift in response. With focus on the male reproductive function in adolescents of first-and second-generation following exposure to protein deficient status, this study aimed to assess effects of protein deficiency on sperm quality parameters.…”