On the one hand, when a man is diagnosed with some kind of fertility issue after a semen analysis, the doctor may prescribe vitamin supplements or a special diet to be followed before turning to infertility treatments.
While trying to boost sperm quality through natural remedies, avoiding the consumption of saturated fats is of utmost importance. In case there exist one or various seminal alterations (low sperm count, low sperm motility...), multivitamin supplements is recommended.
In case it is caused by an infection (presence of leukocytes in the semen sample), antibiotics may be prescribed as well. If it does not work or is a case of non-obstructive azoospermia, maybe you should consider IVF/ICSI.
To learn more about this topic, do not miss this post: Foods to boost sperm quality.