NUTRITION SERIES: Diet and Fertility

Women, nonbinary folk, men, and the relationship between fertility and diet. 

I received this popular question: What IS the relationship? Can diet affect our fertility? 

I have my own risks for infertility, and if that's something important to you, I can understand wanting to do everything you can to optimize the result. While every human body is different and it's always important to talk to your own doctor about what may be best for you, I wanted to present to you what I found from the current research. I am also only talking about the impact that diet CAN have, while there are many, many many other factors that can be far greater causing difficulties with fertility. 

I will also say that the most important message I got from this was that if it had to do with diet, it can be reversed. There are ways to optimize it, while it may not be the fix when there are other underlying causes at play. 

Let's get into it: 

When it comes to nutrition, intake from food and supplements and overall calorie intake can affect fertility primarily by altering the environment that the eggs and sperm develop, and altering the levels of hormones that are involved in reproductive processes (Brown, 2017). Factors caused by nutrition generally have a temporary influence on fertility in which fertility will return to normal once the issue is corrected (Brown, 2017).

I am going to touch on a few different factors from the diet that can be impactful: Iron, full-fat dairy, folate, antioxidants, fruits/vegetables, undernutrition, and protein. 

Vegetarian Diet?

There is currently conflicting evidence that a vegetarian diet can increase fertility - even though the common recommendation is that protein from non-animal sources are better (Fontana et al., 2016). The thought has been that the association is actually just due to insulin sensitivity being increased in women who consume protein solely from vegetable sources, in which case it seems as though merely including sufficient vegetables in the diet is more important and reasonable than cutting meat out (Fontana et al., 2016). As a side note - one of the studies referenced in making this point about insulin sensitivity was only done on men, which absolutely blows my mind considering that female hormones in the reproductive process are completely different than men, have different mechanisms and and will be impacted differently, and I had to bring this up because this is a problem we continue to face:

RESEARCH BEING DONE ONLY ON THE MALE POPULATION AND EXTRAPOLATED ONTO WOMEN! 

I'm not yelling at you, I'm yelling at research. 

To continue, 

The study that found the association between non-animal sources and fertility also only found that association for women over 32 years (Chavarro et al., 2008).

There also were a significant amount of studies referenced showing menstrual disturbances (which, by definition negatively impact fertility) from women on vegetarian diets (Fontana et al., 2016). This could be related to a reduced energy availability (not eating enough) and increased physical activity, however, putting all of the information together, I would lean towards doing both, including a balanced amount of vegetables along with the meat you consume (Fontana et al., 2016). You can get protein from both animal and non-animal sources, maintaining a well-balanced diet closer to what you typically eat without restricting intake, risking reduced energy availability and throwing off your eating patterns (Fontana et al., 2016).

How About Iron? 

Poor iron status prior to pregnancy is common in women of childbearing age, and is related to reduced fertility (Brown, 2017; Chavarro, 2006). There is an emphasis on iron from supplements, as well as from certain sources, in which I have a few listed: 

Beans, lentils, spinach, fortified cereals, long-grain enriched rice and whole grains - along with vitamin C from citrus fruits, bell peppers or berries in your meals to increase the iron absorption (Brown, 2017; Chavarro, 2006; Academy of Nutrition and Dietetics, 2020). There is also evidence that women specfically with risk factors for iron deficiency consuming supplements of iron have increased positive fertility outcomes (Hahn, 2019). 

Folic Acid - Female AND Male Fertility

We are familiar with the link between neural tube defects and folate deficiency in women, however, low folate is also associated with poor fertility - the typically recommended 400 mcg of folic acid is important for both the baby and chances of pregnancy, taken along with the regularly consumed foods with folate in the diet (Panth, 2018; CDC, 2021). The folates in fruits and vegetables are also associated with better sperm characteristics for men (Ricci, 2017).

Antioxidants - Female AND Male Fertility Also

Evidence is continuing to show that consuming antioxidants like Vitamin E, Vitamin C, beta-carotene, selenium, and antioxidant-rich pigments in vegetables and fruits are significant for fertility in women and men (Brown, 2017; Ricci, 2017). The nutrients in antioxidants are needed to protect cells of the reproductive system (such as eggs and sperm) from damage of oxidative stress - which can decrease sperm motility and decrease the ability of sperm to fuse with an egg (Brown, 2017). For women it also can get in the way of implanting the egg in the uterine wall, among other things (Brown, 2017). Diet sources of antioxidants, but also supplements to fix the deficiencies you might already have could be helpful (Brown, 2017).

 Full-Fat Dairy - Yum

Full fat dairy is beneficial for fertility when trying to conceive, it may decrease risk for infertility (Chavarro, 2007; Panth, 2018). 

That's all I have to say about that -Forrest Gump. 

Undernutrition and Fertility

One point I want to drive home is that eating enough is very important for fertility. While there is loads of research to back this up that you can ask me for and I will send you 100 sources, I am going to get to the point. Undernutrition among previously well nourished women is associated with a major decline in fertility, which recovers when intake of food recovers (Brown, 2017). These relatively short periods of insufficient caloric intake, or weight loss, can temporarily decrease fertility in some women (Brown, 2017). With everything you read, make sure you are not cutting food groups out of your diet or restricting your needs. For two reasons - because you matter (psychologically and physically), and for the purposes of, since we're already talking about it, reduced fertility. 

 Balanced Diet

More than anything we always come back to the same conclusions, a balanced diet is going to be important for fertility (and life) (Brown, 2017). If you need a reference point for what that looks like, the MyPlate image from the USDA is a good place to start. 

U.S. Department of Agriculture, 2020

Everyone is different, as I said before, these are just some nutritional factors that can have an impact. This by far does not cover every single nutrient that has an influence, however, it covers some of the bigger dietary factors. I hope you have a good week, and I'll see you back next week to answer another one of your questions! If you have any comments or concerns, please feel free to reach out to me at kyra@kyraarsenault.com or through Facebook or Instagram, as always. 

References

Brown, J.E. (2017). Nutrition Through the Life Cycle Sixth Edition. Cengage Learning. 

Centers for Disease Control and Prevention. (2021). Recommendations: Women and Folic Acid. https://www.cdc.gov/ncbddd/folicacid/recommendations.html#:~:text=The%20Institute%20of%20Medicine's%20Food,with%20a%20neural%20tube%20defect.

Chavarro, J.E., Rich-Edwards, J.W., Rosner, B.A., Willett, W. (2007, May). A prospective study of dairy foods intake and anovulatory infertility. Human Reproduction. 22(5), 1340-7. 10.1093/humrep/dem019.

Chavarro, J.E., Rich-Edwards, J.W., Rosner, B.A., Willett, W. (2006, November). Iron Intake and Risk of Ovulatory Infertility. Obstetrics & Gynecology. 108(5), 1145-1152. 10.1097/01.AOG.0000238333.37423.ab

Chavarro, J.E., Rich-Edwards, J.W., Rosner, B.A., Willett, W. (2008, February). Protein intake and ovulatory infertility. American journal of obstetrics and gynecology. 198(2), 210.e1–210.e2107. https://doi.org/10.1016/j.ajog.2007.06.057
Fontana, R., & Torre, S.D. (2016, February 11). The Deep Correlation between Energy Metabolism and Reproduction: A View on the Effects of Nutrition for Women Fertility. Nutrients. 8(2), 87. 10.3390/nu8020087

Hahn, K.A., Wesselink, A.K., Wise, L.A., Mikkelson, E.M., Cueto, H.T., Tucker, K.L., Vinceti, M., Rothman, K.J., Sorensen, H.T., Hatch, E.E. (2019, June 1). Iron Consumption Is Not Consistently Associated With Fecundability among North American and Danish Pregnancy Planners. The Journal of Nutritional Epidemiology. 149(9), 1585-1595. 10.1093/jn/nxz094.

Kaufman, C. (2020, April 1). Foods That Can Affect Fertility. Academy of Nutrition and Dietetics. https://www.eatright.org/health/pregnancy/fertility-and-reproduction/fertility-foods

U.S. Department of Agriculture. MyPlate. (2020). https://www.myplate.gov/

Panth, N., Gavarkovs, A., Tamez, M., Mattei, J. (2018, July 31). The Influence of Diet on Fertility and the Implications for Public Health Nutrition in the United States. Frontiers in Public Health. 6, 211. 10.3389/fpubh.2018.00211
Ricci, E., Al-Beitawi, S., Cipriani, S., Alteri, A., Chiaffarino, F., Candiani, M., Gerli, S., Vigano, P., Parazzini, F. (2018). Dietary habits and semen parameters: a systematic narrative review. Andrology. 6, 104-116. 10.1111/andr.12452