Zinc and copper as well as several vitamins play a role in the development of sperm cells and their protection from oxidative stress, with possible effects on male fertility. Obesity is associated with several sperm alterations and is also associated with a deficiency of several nutrients due to poor nutrition. What's more, the low-grade inflammation state of obesity produces a depletion of antioxidant molecules.
Metabolic surgery (aka bariatric surgery) is a very effective approach for the treatment of excess weight and the resolution of associated comorbidities. However, even though the levels of reproductive hormones are normalised after weight loss, studies have shown no change, or even worsening, in sperm characteristics after surgery.
The authors of the current study propose that nutritional "derangements" that occur after surgery might be involved in this, most notably the circulating concentrations of some trace elements, especially zinc and copper, as well as some vitamins.
The team followed for two years a group of twenty men, aged 40 ± 8, with grade 2 or 3 obesity - part of a larger cohort - who underwent metabolic surgery. They compared the circulating levels of trace elements and vitamins and found that both retinol and tocopherol were lower after gastric bypass.
There was also a trend for lower circulating concentrations of 25-hydroxyvitamin D, serum copper, zinc and ferritin.Sperm analysis showed that all revaluated patients had abnormal parameters: 60% had low sperm concentrations, 58% low motility and 63% abnormal morphology.
Conversely, Serum TT, SHBG, FT, FSH and inhibin B concentrations increased, showing a beneficial hormonal response for spermatogenesis to occur.
The researchers conclude: "The lack of improvement in sperm quality in obese men after metabolic surgery may be related to nutrient malabsorption, especially zinc, copper and iron. Future research should focus on determining whether routine supplementation of trace elements after metabolic surgery can improve sperm quality."
Weight loss and hormonal response
After metabolic surgery, all patients were placed on a multivitamin and mineral supplement on a daily basis and blood tests were performed after 3, 6, 12 and 24 months to check for possible trace elements or vitamin deficiencies and treat them appropriately.At the end of the two years of follow-up, there was a very important and significant weight loss.
Resolution of obesity comorbidities was achieved in the majority of patients.A significant difference in TSH levels before and after surgery but with no clinical relevance was found, as all patients had normal TSH values. Serum TT, SHBG, FT, FSH and inhibin B concentrations increased, showing a beneficial hormonal response for spermatogenesis to occur.
Conversely, serum copper, zinc and ferritin showed a decline after surgery (Figure 1). Four men (27%) showed copper deficiency, five (33%) zinc deficiency and three (20%) iron deficiency. Four men (27%) showed vitamin D deficiency, one (7%) retinol deficiency and another one (7%) cobalamin deficiency.
After metabolic surgery, all patients were placed on a multivitamin and mineral supplement on a daily basis and blood tests were performed after 3, 6, 12 and 24 months to check for possible trace elements or vitamin deficiencies and treat them appropriately.
At the end of the study, as well as all patients being on a multivitamin and mineral supplement, 18 patients were on cobalamin supplements, 16 patients were on vitamin D, 5 patients were on oral retinol, 12 were on iron supplementation, while zinc was needed in six men and copper in five.
Sperm analysis showed that all revaluated patients had abnormal parameters: 60% had low sperm concentrations, 58% low motility and 63% abnormal morphology. Oligozoospermia was found in nine patients. Sperm volume showed a small decrease and pH a slight increase. The rest of the sperm parameters remained mostly unchanged.
Some of the semen parameters showed significant correlations with trace elements. Serum zinc concentrations showed a positive correlation with progressive motility and serum copper showed a weak and near-significant correlation with motility. Besides, serum ferritin showed a positive correlation with sperm volume, and folate a near significant positive correlation with sperm pH.
The report discusses the limitations of its small sample size: "The relatively small sample size is the main limitation of the present study. It precludes from an appropriate multivariate analysis to correct for possible confounding factors on the statistically significant associations that we found for zinc and ferritin with some sperm parameters. Some findings, such as the associations for copper and folate with sperm parameters, did not reach statistical significance, also because of the small sample size.
"A post hoc sample size analysis shows that at least 25 patients are needed to reach a significant level for the correlation of 0.5 found between folate and sperm pH. In addition, more than 30 patients would be needed to perform a multivariate analysis of the effects of the more relevant independent variables found here (zinc, copper and folate) with sperm parameters."
Botella-Carretero. J. I., et al
"Circulating Zinc and Copper Levels are Associated with Sperm Quality in Obese Men after Metabolic Surgery: A Pilot Study"
https://doi.org/10.3390/nu12113354 (registering DOI)