Infertility, the inability to become pregnant or carry a pregnancy successfully to full term, has become a considerable global and public health concern. While there are many known causes of infertility including auto-immunity, genetic predispositions and endocrine disorders, a number of cases go unsolved, leaving health practitioners wondering: what else could be causing these fertility issues?
Recently, researchers have found that exposure to toxic elements such as lead and mercury can have significant adverse effects on human reproductive health and fertility. Similarly, deficiencies in key trace elements such as selenium and zinc can have just as detrimental a role. With an estimated 1 in 6 Canadian couples being affected by fertility issues[1], we wished to provide a brief list of both toxic and essential elements that may influence your reproductive health.
Toxic Elements:
Lead
Lead is an endocrine-disrupting toxic element that inhibits many of the enzymes involved in the production of sex hormones. In women, increased lead concentrations have been linked to difficulty conceiving and increased incidences of miscarriages and stillbirths.[2] In men, lead exposure has been linked to lowered testosterone, poor sperm quality and infertility.[3-6] To reduce your lead exposure, avoid working with/removing lead-based (i.e.old) paint. Adding a filter to your water tap can also reduce possible exposure, as an avoidance of tobacco products.
Cadmium
Cadmium is another well-known endocrine-disruptor. A common source of exposure is tobacco smoke, since the tobacco plant absorbs this element from the soil. Cadmium exposure has also been linked to lowered levels of reproductive hormones in men, poor sperm quality and infertility.[4-7,11]
Mercury
This toxic element interferes with many proteins involved in steroid hormone production and the reproductive system. Pregnant women especially should avoid exposure to mercury, since the element concentrates in the fetus and affect proper brain development. To avoid mercury exposure, limit your intake of sushi and fish which are high in the food chain such as tuna, swordfish and mackerel.
Tin
Organotin compounds are widely used in marine applications as biocides and antifouling paints, and in agriculture as fungicides. These compounds leach into the surrounding environment, into the water supply and food chain. Both tin and organotin compounds can reduce sperm counts in men, increase aromatase activity, and induce reproductive toxicities leading to an increased risk of infertility.[8-11]
Essential Elements:
Zinc
In women, zinc plays a vital role in many key reproductive health areas including egg production, maintaining proper follicular fluid levels and hormone regulation. Low levels of zinc have been directly linked to miscarriage in the early stages of pregnancy.[12] In men, higher zinc levels in semen lead to higher sperm density and quality which are key measures of male fertility. Infertile men have been shown to have lowered seminal zinc levels, compared to fertile men.[13] Great dietary sources of zinc include lean organic meats, oysters, lentils, cashews, pumpkin seeds, mushrooms and green leafy vegetables.
Selenium
Numerous reports associate selenium deficiency with several reproductive and pregnancy complications including male and female infertility, miscarriage, preeclampsia, fetal growth restriction, preterm labor, and gestational diabetes.[14] Some excellent dietary sources of selenium include brazil nuts, most seeds, brown rice, legumes and mushrooms.
Although this list is far from exhaustive, it provides an idea of the various ways diet, nutrients, and toxic elements may be influencing your reproductive health. If you are looking to get pregnant, talk to your healthcare provider to develop dietary and lifestyle plans that will support your goals.
References:
1. Statistics Canada. (2013, February 4). Fertility [Fact sheet]. Retrieved August 9, 2018, from Government of Canada website: https://www.canada.ca/en/public-health/services/fertility/fertility.html
2. Nordberg et al. Handbook on the Toxicology of Metals. 3rd ed. 2007.Academic Press.
3. Vigeh, M., et al. How does lead induce male infertility? Iran J Reprod Med. 2011. 9(1):1-8.
4. Wirth, J., et al. Adverse effects of low-level heavy metal exposure on male reproductive function. SystBiolReprod Med. 2010. 56(2):147-167.
5. Famurewa, A., et al. Association of blood and seminal plasma cadmium and lead levels with semen quality in non-occupationally exposed infertile men in Abakaliki, southeast Nigeria. J Family Reprod Health. 2017. 11(2):97-103.
6. Kiziler, A., et al. High levels of cadmium and lead in seminal fluid and blood of smoking men are associated with high oxidative stress and damage in infertile subjects. Biol Trace Elem Res. 2007. 120(1-3):82-91.
7. Xu, B., et al. Trace elements in blood and seminal plasma and their relationship to sperm quality. ReprodToxicol. 1993. 7(6):613-618.
8. Nakanishi, T. Endocrine disruption induced by organotin compounds; Organotins function as a powerful agonist for nuclear receptors rather than an aromatase inhibitor. J Toxicol Sci. 2008. 33(3):269-276.
9. Graceli, J., et al. Organotins: a review of their reproductive toxicity, biochemistry, and environmental fate. ReprodToxicol. 2013. 36:40-52.
10. Delgado Filho, V., et al. Triorganotin as a compound with potential reproductive toxicity in mammals. Braz J Med Biol Res. 2011. 44(9):958-965.
11. Guzikowski, W., et al. Trace elements in seminal plasma of men from infertile couples. Arch Med Sci. 2015. 3:592-598.
12. Assisted Reproductive Technology (ART). (n.d.). Retrieved from https://www.cdc.gov/art/index.html
13. Colager, A., et al. Zinc levels in seminal plasma are associated with sperm quality in fertile and infertile men. Nutr Res. 2009. 29(2):82-88.
14. Hiten D. Mistry et al. Selenium in reproductive health. American Journal of Obstetrics and Gynecology. January 2012. 206;1:21-30. https://doi.org/10.1016/j.ajog.2011.07.034
