It is estimated that 15% of couples are infertile and of these the male factor is involved in the range of 20-70%. After eliminating "detectable" causes of male infertility, 45% of men are classified as having "idiopathic" infertility, and most of these men have suboptimal semen quality (WHO criteria, 2012).
A multitude of studies have been published to observe the improvement of semen quality with the use of "natural" compounds, which mainly aim to improve sperm concentration and sperm motility. In the scientific literature, taking into account the degrees of evidence usually used for the validation/prescription of treatments, none of them has shown a great deal of evidence and therefore their use is only weakly recommended by the scientific societies.
Recently several meta-analyses (compilation and critical reading of the accumulated scientific evidence) have been published which tell us the same thing. In any case, there is some evidence of improvement in semen quality with regard to the use of: co-enzyme Q10, long-chain omega 3-6 fatty acids, L-carnitine, FSH, tamoxifen and kallikrein. The overall conclusion of these articles is that there is some evidence that empirical medical treatments and nutritional therapy can improve semen quality, but even less evidence that this results in increased pregnancies and births.
The lack of scientific evidence in these aspects is due to the fact that the study groups are often not comparable, the studies have important biases or are restrospective case series. All this means that the conclusions of the studies cannot be considered as valid as would be desirable. More complete prospective studies would be necessary to better establish the role of these treatments.
What has been demonstrated throughout different studies are those quality of life factors that can be considered as clearly associated with semen quality: diet, stress, physical exercise, toxic habits (alcohol, tobacco, drugs), overweight or obesity and lack of sleep.
At present, in the case of a male with suboptimal semen quality due to idiopathic causes, we recommend correcting habits, trying to improve the diet by being more balanced and limiting animal fat, and getting at least 7 hours of sleep. In addition, physical exercise should be done on a regular basis but it should not be strenuous exercise, as competitive sports have been shown to cause physical stress that decreases semen quality. We add a dietary supplement that includes at least L-carnitine, Coenzyme Q-10 and omega 3-6 fatty acids. This treatment should be maintained for at least 3 months so that at least one cycle of spermatogenesis (62-75 days) is affected by this treatment, and desirably until pregnancy is achieved.