Introduction
Metabolic syndrome (MetS) is a cluster of abnormalities, including hypertension, dyslipidemia, obesity, and insulin resistance. It was first identified by Kylin in the early 20th century when he first described a trio of metabolic disorders: hypertension, hyperglycemia, and gout. Vague discovered a link between upper body adiposity, hypertension, and diabetes in the 1940s, and Haller and Hanefeld first used the term MetS to describe this dangerous confluence of concurrent risk factors (diabetes, cardiovascular disease) in 1975. Later on, other terms like syndrome X (1988), the deadly quartet (1989), and the insulin resistance syndrome were coined (1992).
According to a National Health Survey, more than one in five Americans have metabolic syndrome. In addition, age-related increases in the prevalence of metabolic syndrome affect more than 40 % of people in their 60s and 70s. People who typically develop metabolic syndrome include:
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People who are centrally obese (more fat in the waist/abdomen).
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People who have diabetes mellitus or who have a strong family history of the disease.
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Individuals with additional "insulin resistance" clinical symptoms, such as skin tags or acanthosis nigricans (darkened skin) at the back of the neck (usually on the neck).
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The risk of developing metabolic syndrome is higher in certain racial and ethnic groups.
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The risk of developing metabolic syndrome rises as one age.
What Is Metabolic Syndrome?
Metabolic syndrome (MetS) is a cluster of systemic disorders that includes insulin resistance, obesity, dyslipidemia, and hypertension. The risk factors include:
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High blood pressure, including using blood pressure medications.
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High blood sugar (insulin resistance) or using blood sugar-lowering medication.
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Excess fat around the waist.
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Having high triglyceride levels or using medication to lower them.
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Low levels of HDL or good cholesterol, or using medication to treat low HDL.
Even if one has one of these risk factors, metabolic syndrome is not guaranteed. But having one will increase the likelihood of getting cardiovascular disease. One will be diagnosed with metabolic syndrome in the presence of three or more of these conditions, which increases the risk of developing medical conditions like type 2 diabetes.
What Is the Relation Between Metabolic Syndrome and Male Infertility?
Even though each condition that falls under the definition of MetS impacts male fertility, these metabolic conditions can combine to have additive effects on fertility. Recent research has looked at how MetS affect male fertility. In 2013, Lotti et al. investigated the relationship between men with MetS and the clinical traits of infertile couples. An age-adjusted model in this study demonstrated that MetS was linked to a decline in total testosterone without changes in gonadotropin levels. In a univariate analysis, the same study found a negative correlation between the quantity of MetS components and both progressive motility and normal morphology; however, when the study was corrected for age and total testosterone, only normal morphology continued to exhibit this negative correlation.
Even after adjusting for age and testosterone levels, the number of MetS factors increased the risk of erectile dysfunction (ED). In men of infertile couples, this study showed a connection between MetS and the presence of hypogonadism, a decline in normal sperm morphology, and ED. One year later, the same group examined the connection between infertile men's prostatic abnormalities and MetS. The authors found that insulin levels increased as a function of MetS components and demonstrated an inverse correlation with total testosterone levels in an age-adjusted model.
Additionally, this study found that, in an age-testosterone-insulin adjusted model, there was a negative correlation between MetS components and healthy sperm morphology and a positive correlation between MetS components and interleukin-8 (a marker of prostate inflammation), prostate total and transitional zone volume, arterial peak systolic velocity, texture homogeneity, and calcification size. Leisegang et al. compared male patients with and without MetS and found that men with MetS had lower sperm concentration, total motility, total sperm count, mitochondrial membrane potential, sperm viability, free testosterone, and progesterone levels, as well as higher sperm DNA fragmentation.
According to the NCEP-ATP III criteria, Ventimiglia et al. examined men who presented with primary infertility with or without MetS in 2016. Infertile men with MetS had lower levels of total testosterone, sex hormone-binding globulin (SHBG), inhibin B, and anti-Müllerian hormone than infertile men without the condition. They were also more likely to be hypogonadal (AMH). Semen parameters between the two groups, however, showed no differences. A more recent study compared the semen and hormone parameters of fertile and infertile men. The authors could not replicate a significant independent effect of MetS on major fertility parameters in either group, except for a significant negative association between MetS and total testosterone levels in both groups. These studies raise the possibility that MetS may have a negative impact on crucial reproductive processes like endocrine status or semen parameters and urge the development of additional, better-designed studies to establish this association definitively.
Does the Management of Metabolic Syndrome Affect Fertility?
The cornerstone of treating MetS is weight loss through adopting a healthy lifestyle and regular exercise. As losing weight would lessen the detrimental effects of obesity on human reproduction, sperm quality is anticipated to improve. Studies investigating the impact of natural weight loss on male fertility have validated this notion. Semen samples from men who underwent a 14-week weight loss program and had a BMI of more than 33 kg/m2 were examined. The median percentage of weight loss after the intervention was 15 %. There was also an increase in the number of sperm overall, semen volume, testosterone, SHBG, and AMH.
In a larger study by Jaffar, overweight men who received diet counseling and exercised lost a mean of 2.2 kg/m2 from BMI. The percentage of progressive sperm motility and the static percentage of weight loss were found to be significantly positively correlated by the author. On the other hand, the impact of weight loss after bariatric surgery on semen parameters and male fertility is still debatable, with some studies reporting no or a negative impact and others discovering an improvement. The imbalance may explain the observed worsening in semen parameters that occur soon after surgery in electrolytes and nutrients seen after these malabsorptive procedures. However, more recent data showed that semen parameters significantly improved after surgery with longer follow-up periods.
Conclusion
MetS is almost at a pandemic level of expansion worldwide. Obesity, insulin resistance, dyslipidemia, and hypertension are its main constituents, and they can all negatively impact various human health conditions. Male fertility is one condition that MetS can affect via various mechanisms. MetS side effects that can affect sperm production and function and, ultimately, male fertility include oxidative stress, scrotal temperature elevation, dysregulation of the endocrine system, and altered erectile and ejaculatory functions. To avoid the negative effects of MetS on fecundity and general health and well-being, it is essential to lead a healthy lifestyle that includes a balanced diet and regular exercise.
