Between 1996 and 2005, 3,457 Danish young men were approached when they attended a compulsory physical examination to determine their fitness for military service.
The researchers objective was to study the relationship between self-rated health (SRH) and semen quality.
The men delivered a semen sample, had a physical examination performed, and responded to a questionnaire including a question about self-rated health1.
In order to deliver statistically significant results the questionnaires were ranked against semen quality and testicle size.
- Men with very good self-rated health had between 0.5 mL and 0.8 mL larger testes compared to men with good and poor self-rated health. This trend was statistically significant.
- Men with very good self-rated health had between 12.2% and 26.9% higher total sperm count compared to men with good and poor self-rated health and had +0.4% and 1.4% more morphologically normal sperms. Again, this trend was statistically significant.
- Percentages of motile spermatozoa and semen volume were not significantly associated with self-rated health.
The study found significant associations between self-rated health and semen quality and testicular size. The study had a cross-sectional design, which means that data is collected at one specific point in time. The researchers could therefore not establish a more conclusive relationship of what specific habits improved fertility over time. Although, they argued that self-rated health may be associated with semen quality.
Physical health is directly reflected in sperm health
Human sperm are particularly sensitive to environmental influences. These can include physical trauma, temperature, supply of nutrients, exposure to toxins from the diet or oxidative stress2.
We as individuals are able to judge our physical fitness, diet and immune system strength best. If a man feels good about his health, chances are that he is indeed healthy. This will be directly reflected in his semen quality and therefore fertility.
After all, this is also proof of Charles Darwin’s theory of Natural Selection.