Men’s semen quality is associated with how long they live according to a study of nearly 80,000 men, which is published today (Wednesday) in Human Reproduction [1], one of the world’s leading reproductive medicine journals.

The study followed the men for up to 50 years and found that those with a total number of motile sperm (sperm that can move or ‘swim’) of more than 120 million could expect to live two to three years longer than men with a total motile sperm count of between 0 and 5 million.

This is the largest study to examine the link between semen quality and mortality. An accompanying editorial commentary calls it a “landmark” publication [2].

The research was led by Dr Lærke Priskorn, a senior researcher, and Dr Niels Jørgensen, chief andrologist, both working in the Department of Growth and Reproduction at Copenhagen University Hospital—Rigshospitalet, Copenhagen, Denmark. They analysed data from 78,284 men who had their semen quality assessed between 1965 and 2015 at the public semen analysis laboratory in Copenhagen due to reported couple infertility. This meant that semen quality among the men ranged from very good to those with no sperm. Assessment of semen quality included semen volume, sperm concentration, and the proportion of sperm that were motile and a normal shape.

During the follow-up period, the researchers used the data contained in unique Danish national registers, to see how many died from any cause. During this time there were 8,600 deaths, representing 11% of this group of men. Out of this group, 59,657 men provided semen samples between 1987 and 2015, and for this group more information was available, including educational level as an indicator of socioeconomic status, and registered diagnoses of medical conditions in the ten years prior to giving a sample.

The researchers adjusted their analyses to take account of the extra information that was available for the men who gave samples from 1987 onwards as that could affect the results.

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University of Newcastle, Australia, calls it a “landmark” publication and sets out the various mechanisms that could be contributing to the link between poor semen quality and shorter life span.

“In this commentary, I have highlighted several potential mediators of such an association including genetic defects on the sex chromosomes (X or Y), a compromised immune system, comorbidities, lifestyle factors and chemical pollutants capable of compromising telomeric integrity. Given the complexity of these factors, we might ask whether they are acting independently, or do they reflect the existence of some fundamental pathological process that cuts across all of these epidemiological pathways?” he writes.

He suggests a process called oxidative stress could be involved in the process. This is an imbalance in the body of molecules called ‘free radicals’ and antioxidants, which inhibit oxidation. Free radicals are known to damage cells and to influence semen quality, and oxidative stress is known to be involved in the aging process.

He writes: “Any factor (genetic, immunological, metabolic, environmental or lifestyle) that enhances overall levels of oxidative stress, could reasonably be expected to drive changes in the semen profile and subsequent patterns of mortality, as observed by Priskorn et al. . . . Furthermore, an aetiology grounded in oxidative stress might also explain the relationships observed between complications of pregnancy (preeclampsia, gestational hypertension and gestational diabetes) and female mortality later in life . . . An overarching oxidative stress hypothesis also accords with the observation that circulating antioxidant levels are generally higher in women than men, just as their telomeres are usually longer . . . So perhaps, for both genders, the secret to achieving both high fecundity and heathy ageing, is to monitor oxidative stress and adopt measures to maintain a balanced redox state. Could it be that simple? Clearly, much food for thought.”

IMAGE CREDIT: NASA.