How does dairy fit into a fertility diet?

Dairy products such as milk, cheese, yoghurt, cream and butter are staples in many households and provide essential nutrients for health and fertility including calcium, phosphorus, vitamin A, vitamins B2, B12, protein, potassium, zinc, choline, magnesium and selenium. The current guidance in the UK is to consume moderate amounts of dairy or dairy alternatives daily, with the recommendation to choose low fat options. So why are there questions around consumption of dairy and fertility and where do they come from?

Full fat versus low fat dairy and fertility?

This question came following the results of the Nurses Health Study in 2007. This study looked at the diets of 18,500 women with anovulatory infertility and suggested that women whose diet comprised of plant based protein, full-fat dairy foods, iron, and monounsaturated fats, during the preconception period had lower risk of infertility related to ovulatory disorders and a lower risk of infertility due to other causes compared to women consuming low fat dairy (1,2). In order to try and understand more, another study conducted in a group of Danish and American women aimed to assess the influence of dairy consumption on time to pregnancy (3). The study however showed inconsistent results between the two geographical groups of women, and was not able to show a clear association between either low- or high-fat dairy consumption, and time to pregnancy in either group. However, due to the significant results seen in the 2007 study with a large cohort, many women choose to consume high fat dairy to promote their fertility. The fat content of whole milk dairy foods may affect fertility by modulating the levels of oestrogen in the body however, more research is needed to fully understand the mechanisms that may mediate the beneficial effects of full fat dairy on fertility (4).

How important is dairy for fertility - nutritional value of dairy?

Dairy foods boast an impressive nutritional value. They are sources of calcium, which is important both pre and during pregnancy to aid the formation and development of the unborn baby's bones. It is also a significant source of iodine (11), it is important to consume enough iodine in your diet for several months before getting pregnant in order to optimise fertility and foetal growth. Vitamins B2, B12, vitamin A, choline, zinc, magnesium and selenium are also found in dairy, all of which play important roles in fertility.

Dairy and IVF, PCOS and endometriosis

While data is scarce on the role of dairy in IVF outcomes, one study found that milk intake produced no harm on IVF outcomes and was associated with higher chances of live birth (6). Dairy consumption could also be beneficial for women suffering from endometriosis (7,8), with its beneficial effects potentially being mediated through reduction of oxidative and inflammatory stress, as well as the gut microbiome.

On the other hand, dairy has the ability to produce an insulin response therefore, for women with PCOS, being mindful of when dairy is consumed could help with daily blood glucose and insulin control and ultimately fertility outcomes (9).

Dairy intake and male fertility

While the data suggests high-fat dairy may be a better choice for women, it is not the same story for men. Evidence from several studies links low-fat dairy to improved sperm concentration and motility and full fat dairy, in particular full fat cheese, with lower sperm concentration (10). This doesn’t mean men need to avoid dairy altogether however low fat dairy options may be the best choice.

The bottom line

Dairy is a great addition to a fertility diet as long as an intolerance or allergy is not present due to its impressive nutritional value. If you enjoy milk as part of your diet, as a woman drinking whole milk for fertility and choosing some full fat options while trying to conceive may improve chances of conception and for men choosing lower fat options may be best. If you do not wish to consume dairy as part of your diet, selecting dairy free nutritionally fortified options will ensure you are consuming the nutrients you require to optimise fertility and ultimately a healthy pregnancy.

References

1. Mph JW, Chavarro JE. Diet and Lifestyle in the Prevention of Ovulatory Disorder Infertility. 2007 [cited 2020 Jun 17];110. Available from: http://journals.lww.com/greenjournal/Fulltext/2007/11000/Diet_and_Lifestyle_in_the_Prevention_of_Ovulatory.17.aspx
2. Chavarro JE, Rich-Edwards JW, Rosner B, Willett WC. A prospective study of dairy foods intake and anovulatory infertility. Hum Reprod [Internet]. 2007 [cited 2020 Sep 15];22(5):1340–7. Available from: https://pubmed.ncbi.nlm.nih.gov/17329264/
3. Wise LA, Wesselink AK, Mikkelsen EM, Cueto H, Hahn KA, Rothman KJ, et al. Dairy intake and fecundability in 2 preconception cohort studies. Am J Clin Nutr [Internet]. 2017 Jan 1 [cited 2020 Sep 15];105(1):100–10. Available from: /pmc/articles/PMC5183724/?report=abstract
4. Kim K, Wactawski-Wende J, Michels KA, Plowden TC, Chaljub EN, Sjaarda LA, et al. Dairy food intake is associated with reproductive hormones and sporadic anovulation among healthy premenopausal women. J Nutr [Internet]. 2017 [cited 2020 Sep 15];147(2):218–26. Available from: /pmc/articles/PMC5265695/?report=abstract
5. Cramer DW, Xu H, Sahi T. Adult hypolactasia, milk consumption, and age-specific fertility. Am J Epidemiol [Internet]. 1994 Feb 1 [cited 2020 Sep 15];139(3):282–9. Available from: https://pubmed.ncbi.nlm.nih.gov/8116603/
6. Afeiche MC, Chiu YH, Gaskins AJ, Williams PL, Souter I, Wright DL, et al. Dairy intake in relation to in vitro fertilization outcomes among women from a fertility clinic. Hum Reprod [Internet]. 2016 Mar 1 [cited 2020 Sep 15];31(3):563–71. Available from: https://pubmed.ncbi.nlm.nih.gov/26787645/
7. Nodler JL, Harris HR, Chavarro JE, Frazier AL, Missmer SA. Dairy consumption during adolescence and endometriosis risk. In: American Journal of Obstetrics and Gynecology [Internet]. Mosby Inc.; 2020 [cited 2020 Sep 15]. p. 257.e1-257.e16. Available from: https://pubmed.ncbi.nlm.nih.gov/31526789/
8. Harris HR, Chavarro JE, Malspeis S, Willett WC, Missmer SA. Dairy-food, calcium, magnesium, and vitamin D intake and endometriosis: A prospective cohort study. Am J Epidemiol [Internet]. 2013 Mar 1 [cited 2020 Sep 15];177(5):420–30. Available from: /pmc/articles/PMC3626048/?report=abstract
9. Phy Ali M JL. Low Starch/Low Dairy Diet Results in Successful Treatment of Obesity and Co- Morbidities Linked to Polycystic Ovary Syndrome (PCOS). J Obes Weight Loss Ther [Internet]. 2015 [cited 2020 Sep 15];05(02). Available from: /pmc/articles/PMC4516387/?report=abstract
10. Afeiche MC, Bridges ND, Williams PL, Gaskins AJ, Tanrikut C, Petrozza JC, et al. Dairy intake and semen quality among men attending a fertility clinic. Fertil Steril [Internet]. 2014 [cited 2020 Sep 15];101(5):1280. Available from: /pmc/articles/PMC4008690/?report=abstract
11. Abel MH, Caspersen IH, Sengpiel V, Jacobsson B, Meltzer HM, Magnus P, et al. Insufficient maternal iodine intake is associated with subfecundity, reduced foetal growth, and adverse pregnancy outcomes in the Norwegian Mother, Father and Child Cohort Study. BMC Med [Internet]. 2020 Aug 11 [cited 2020 Sep 15];18(1). Available from: https://pubmed.ncbi.nlm.nih.gov/32778101/