A recent study published in the journal ‘Human Reproduction’ highlights the decline in male fertility over recent years. The comprehensive French study investigated the reproductive health of 26, 609 men over 17 years. The results revealed a significant and continuous decline in fertility.
On average, men who participated in this study showed a reduction in sperm concentration by 1.9 percent per year, leading to a total decline of more than 32 percent over the 17 year study period 1. Similar studies across the world are also highlighting the decline in male fertility.
Oxidative Stress & Male Fertility
Oxidative stress arises when the balance between antioxidant defences and the reactive oxygen species (ROS) within the body are disrupted.
This unbalance leads to an increase in free radicals. Free radicals damage cells, causing oxidative stress. These free radicals can harm sperm cells and cause a decline in fertility.
There are many factors that can contribute to oxidative stress. As we age, the free radical concentration within our body increases as a result of our behavior and the environment we live in.
Some of leading causes of oxidative stress include: exposure to pollutants and chemicals, psychological stress, alcohol and tobacco use, pharmaceutical medications, unbalanced diet, obesity, and inactivity, amongst others. However, the good news is that oxidative stress can be combated through antioxidants.
What Are Antioxidants?
Antioxidants are types of molecules that prevent the oxidation of other molecules and hence, stop the build up of damaging free radicals.
Antioxidants can help to break the chain reaction instigated by free radicals, as well as working to prevent free radicals from triggering a chain reaction in the first instance. There are two main types of antioxidants classified based on their solubility. Those soluble in water are hydrophilic antioxidants and those that are soluble in lipids are hydrophobic antioxidants.
Research has identified oxidative stress as the primary cause of a decline in male fertility in 30 to 80 percent of cases2. These studies have also shown that men with poor fertility also have low antioxidant levels within their semen when compared to fertile men.
Thus, it’s a logical assumption that boosting antioxidant concentrations may help to reverse or prevent a decline in male fertility. Multiple clinical trials involving 2,876 couples have shown that men with low sperm concentrations are able to boost conception rates as a result of taking antioxidant supplements3.
How Can Antioxidants Benefit Male Fertility?
There are several different antioxidant containing compounds that have been shown to reduce seminal oxidative stress levels. These include carnitine, vitamins E and C, selenium, glutathione and carotenoids.
An important hydrophobic antioxidant, vitamin E has been reported to help treat infertile men with high ROS6. Vitamin E enhances the activity of a range of antioxidants involved in scavenging free radicals.
Also known as ascorbic acid, vitamin C is a very potent hydrophilic antioxidant. Research suggests that vitamin C supplementation alongside vitamin E may help to decrease oxidative damage against sperm7.
Another important antioxidant, selenium (Se) is necessary for testicular development, spermatogenisis, function and motility. While the process is not well understood, studies have shown that Se helps to eliminate oxidative stress in association with vitamin E8.
One of the most powerful and abundant antioxidants within the body is glutathione (GSH). Synthesised from the amino acids cysteine and glutamic acid, this nutrient combines with Se and vitamin E to produce glutathione peroxidise. Studies have shown that glutathione supplementation can improve sperm functionality9.
These organic pigments are found within plant chloroplasts and chromoplasts. There are more than 600 known carotenoids and many of them have antioxidant properties that can help improve male fertility. Carotenoids, astaxanthin and lycopene, have both been shown to have positive effects on sperm concentration10 11.
It’s also important to note that zinc is required in trace amounts to maintain optimal functional levels of antioxidant enzymes. Zinc deficiency is known to reduce male fertility12. However, it’s essential that zinc is present in trace amounts, as too much will have toxic effects on the body.
Best Sources of Antioxidants
In order for antioxidants to neutralise free radicals, they become oxidised themselves. Consequently, they must be constantly replenished in order to retain an optimal balance.
Although the body can manufacture its own antioxidants, often internal supplies become diminished and they are needed to be sourced externally. Many foods are rich in antioxidants and highly recommended not only to improve male fertility, but to also enhance overall well-being.
Common antioxidant rich foods include berries, broccoli, garlic, beans, legumes, tomatoes, whole grains, spinach, red grapes, artichokes, nuts, and seeds, amongst others. A healthy diet containing a regular intake of antioxidant rich foods will help to reduce oxidative stress.
In turn, sperm concentration and motility will improve, and overall reproductive health will be enhanced. While fresh foods are the ideal antioxidant source, there are also many different supplements available that can be beneficial.
Declining male fertility is largely a physiological response to an increase in oxidative stress within the body. This oxidative stress is brought about not only through aging, but also through our lifestyle choices and the behaviours we exhibit.
While there are many changes that can be made to try and improve fertility, simple dietary adjustments are one of the easiest and most effective measures. There are plenty of antioxidant rich food sources and supplements available to help boost male reproductive health.
Antioxidants also have the added benefit of supporting other physiological and pathological processes within the body, as well as protecting the body from disease. A diet rich in antioxidants will offer individuals many health advantages.
- Rolland M, Le Moal J, Wagner V, Royère D, De Mouzon J. Decline in semen concentration and morphology in a sample of 26,609 men close to general population between 1989 and 2005 in France. Human Reproduction. 2013. 28(2): 462-70 ↩
- Tremellen K. Oxidative stress and male infertility-a clinical perspective. Human Reproduction Update. 2008. 14(3): 243-58 ↩
- Showell MG, Brown J, Yazdani A, Stankiewicz MT, Hart RJ. Antioxidants for male subfertility. Cochrane Database of Systematic Reviews. 2011. 1 ↩
- Cavallini G, Ferraretti AP, Gianaroli L, Biagiotti G, Vitali G. Cinnoxicam and L-carnitine/acetyl-L-carnitine treatment for idiopathic and varicocele-associated oligoasthenospermia. Journal of Andrology. 2004. 25(5): 761-70 ↩
- Lenzi A, Lombardo F, Sgrò P, Salacone P, Caponecchia L, Dondero F, Gandini L. Use of carnitine therapy in selected cases of male factor infertility: a double-blind crossover trial. Fertility and Sterility. 2003. 79(2): 292-300 ↩
- Ross C, Morriss A, Khairy M, Khalaf Y, Braude P, Coomarasamy A, El-Toukhy T. A systematic review of the effect of oral antioxidants on male infertility. Reproductive Biomedicine Online. 2010. 20(6): 711-23 ↩
- Baker HW, Brindle J, Irvine DS, Aitken RJ. Protective effect of antioxidants on the impairment of sperm motility by activated polymorphonuclear leukocytes. Fertility and Sterility. 1996. 65(2): 411-9 ↩
- Keskes-Ammar L, Feki-Chakroun N, Rebai T, Sahnoun Z, Ghozzi H, Hammami S, Zghal K, Fki H, Damak J, Bahloul A. Sperm oxidative stress and the effect of an oral vitamin E and selenium supplement on semen quality in infertile men. Archives of Andrology. 2003. 49(2):83-94 ↩
- Lenzi A, Culasso F, Gandini L, Lombardo F, Dondero F. Placebo-controlled, double-blind, cross-over trial of glutathione therapy in male infertility. Human Reproduction. 1993. 8(10): 1657-62 ↩
- Comhaire FH, El Garem Y, Mahmoud A, Eertmans F, Schoonjans F. Combined conventional/antioxidant “Astaxanthin” treatment for male infertility: a double blind, randomized trial. Asian Journal of Andrology. 2005. 7(3): 257-62 ↩
- Gupta NP, Kumar R. Lycopene therapy in idiopathic male infertility-a preliminary report. International Urology and Nephrology. 2002. 34(3): 369-72 ↩
- Chia SE, Ong CN, Chua LH, Ho LM, Tay SK. Comparison of zinc concentrations in blood and seminal plasma and the various sperm parameters between fertile and infertile men. Journal of Andrology. 2000. 21(1): 53-7 ↩