Lycopene and fertility: clinical evidence
Oxidative stress, sperm count and lycopene
Lycopene and male infertility. Damayanthi Durairajanayagam, Ashok Agarwal, Chloe Ong, and Pallavi Prashast
Excessive amounts of reactive oxygen species (ROS) cause a state of oxidative stress, which result in sperm membrane lipid peroxidation, DNA damage and apoptosis, leading to decreased sperm viability and motility. Elevated levels of ROS are a major cause of idiopathic male factor infertility, which is an increasingly common problem. Lycopene, the most potent singlet oxygen quencher of all carotenoids, is a possible treatment option for male infertility because of its antioxidant properties. By reacting with and neutralizing free radicals, lycopene could reduce the incidence of oxidative stress and thus, lessen the damage that would otherwise be inflicted on spermatozoa. It is postulated that lycopene may have other beneficial effects via nonoxidative mechanisms in the testis, such as gap junction communication, modulation of gene expression, regulation of the cell cycle and immunoenhancement. Various lycopene supplementation studies conducted on both humans and animals have shown promising results in alleviating male infertility—lipid peroxidation and DNA damage were decreased, while sperm count and viability, and general immunity were increased. Improvement of these parameters indicates a reduction in oxidative stress, and thus the spermatozoa is less vulnerable to oxidative damage, which increases the chances of a normal sperm fertilizing the egg. Human trials have reported improvement in sperm parameters and pregnancy rates with supplementation of 4–8 mg of lycopene daily for 3–12 months. However, further detailed and extensive research is still required to determine the dosage and the usefulness of lycopene as a treatment for male infertility.
Evidence for historic decline in sperm count
Temporal trends in sperm count: a systematic review and meta-regression analysis. Hagai Levine, Niels Jørgensen, Anderson Martino-Andrade, Jaime Mendiola, Dan Weksler-Derri, Irina Mindlis, Rachel Pinotti, and Shanna H. Swan
This comprehensive meta-regression analysis draws on 185 studies, which included 42,935 men who provided semen samples between 1973 and 2011. It reports a signiﬁcant decline in sperm counts during this period, driven by a 50–60% decline among men unselected by fertility from North America, Europe, Australia and New Zealand. There are signiﬁcant public health implications to these results; research on the causes of this continuing decline is urgently needed.