There are many different versions of a plant-based diet. When I say plant-based, I mean abundant with fresh, whole foods, mostly consisting of vegetables, fruits, nuts, seeds, beans, whole grains, and legumes. You may choose to include organic dairy or seafood, and that is perfectly ok. What I am not advocating for is a junk food vegan diet full of processed ingredients and lacking in essential nutrients.
Many people are wary of plant-based or vegan diets because they have a poor reputation of not providing enough nutrients. However, there are many other diets where deficiencies do occur. For instance, if you avoid grains, you might be depriving yourself of adequate folate. Or, using fancy sea salt? You might not be getting enough of the mineral iodine. The bottom line is that any poorly planned diet can be lacking essential nutrients which may impact your fertility.
There is a substantial amount of evidence showing that a diet rich in plant foods is a great place to start to boost fertility. Not only are plants packed full of many of the vitamins and minerals that support reproduction, such as folate, vitamin B6, zinc, iodine, iron, selenium and a variety of antioxidants.
A diet rich in plant foods will also help reduce inflammation. Inflammation can alter and impact your immune system, which in turn affects your fertility.
What you and your partner eat may hinder or enhance your chances of conceiving. Nutrients from food (and supplements) are fundamental building blocks for hormones and to support the optimal functioning of reproductive tissues. So, what are the pro’s and con’s of a plant-based diet? Is it a viable option is you are planning to conceive and what things do you need to keep in mind?
The Pros:
Decreases the risk of anovulatory infertility
A prospective study showed that dairy foods, in particular, low-fat dairy foods, have been shown to increase the risk of anovulatory infertility compared to full-fat dairy products. 1
Naturally being abundant in folate, a plant-based diet results in a lower frequency of sporadic anovulation, as shown in a prospective cohort study amongst young, healthy women. 2
Provides ample amounts of antioxidants
Plants naturally offer copious amounts of antioxidants, which protecting your cells against oxidative stress. Supplemental antioxidants are particularly beneficial for men, whose female spouses are undergoing infertility treatment. 3 Antioxidants improve semen quality and clinical pregnancy rates. 4
A great way of getting more antioxidants in your diet is to load up your meals with vegetables, herbs, spices, and fruits.
Reduces risk of preeclampsia
Plant foods are a rich source of Vitamin E, which may assist in the prevention of late pregnancy complications like preeclampsia. 5 Be sure to include sources of vitamin E, including nuts, seeds, and cold-pressed olive oil.
Supports gut health
The maternal gut microbiome is crucial for fetal microbial colonization. 6 Consuming more plant foods will provide your gut with abundant prebiotics which provides fuel for good bacteria that will consequently be transferred to your baby during a vaginal delivery.
Can provide ample iodine to support thyroid health in pregnancy.
Iodine deficiency is relatively common in Australia. Iodine is crucial for producing thyroid hormones that are responsible for regulating the metabolic rate and encourages the growth and development of your baby. Without iodine, early fetal brain development may be impaired. 7
Seaweed is one of the best sources of iodine. Other sources include seafood, fortified bread and iodised seat salt.
Tip: Supplement with 150 mcg of iodine (as in most prenatal multivitamins) and consume iodine-rich foods in your diet to achieve the recommended daily intake of 220 mcg per day both in the preparation for pregnancy and during. 8
Can provide adequate amounts of protein
It’s a myth that plant-based diets cannot provide adequate protein. In fact, plant-based source over animal source may actually improve fertility in women. A large prospective cohort study showed that vegetable sources of protein over animal sources, during the preconception period had a 66% lower risk of infertility related ovulatory disorders. 1 Protein is abundant in foods such as beans (including soy) and legumes, nuts, seeds and whole grains.
While there is much controversy that surrounds soy, the evidence is now pointing towards soy products like tempeh and tofu to be beneficial for fertility. Around one serve of soy foods per day has been shown to increase pregnancy rates. 9 The majority of studies, specifically on couples undergoing assisted reproduction or IVF, showed an overall positive benefit for both dietary soy intake for both men and women. 10
Reducing environmental toxin exposure
Adopting a plant-based diet may help to reduce your toxic load.
Dioxins are an industrial chemical that is a persistent environmental pollutant and is very slow degrading. It is detectable in the food chain including seafood, non-organic meat and dairy products. Dioxin can accumulated in the adipose tissue of humans and animals and traces can sadly be found in human breast milk. 11 Though its exact mechanisms on fertility are unknown in humans, from animal studies we know it disrupts the endocrine system and can lead to reproductive issues.
When eating whole foods, exposure to bisphenol A (BPA) plastics significantly reduced. All of these may be detrimental to fertility in both men12 and women. 13 Avoid tinned foods, disposable coffee cups, plastic water bottles and soft plastic containers when possible to reduce your exposure to BPA.
The Con’s:
Potential inadequate intakes of choline and vitamin B12
It gets tricky trying to get the recommended 440 mg daily intake of choline during pregnancy. 14 Choline plays a pivotal role in protecting against neural tube defects and supports DNA methylation. 15 Choline is primarily found in eggs, seafood, dairy and meat products. To a lesser extent choline can be found in broccoli, cauliflower, peanuts and chickpeas.
Likewise, vitamin B12 is abundantly found in animal products but is non-existent in plant foods. A strictly plant-based diet may require additional vitamin B12 supplementation. It’s always a good idea to keep a close check on blood vitamin B12 when planning for a pregnancy and once pregnant.
High fibre limiting digestive space
Growing a little one takes up a lot of room, and so does a diet high in fibre when eating majority plants. Reduced digestive space is more of an issue in later pregnancy and we need to be very careful the caloric and micronutrient requirement are being met. Nevertheless, the diet can be altered by accompanying low-fibre foods while still fulfilling all nutrient requirements.
Phytic acid that reduces mineral absorption
Phytic acid is an antinutrient found naturally in seeds, nuts, grains, and legumes and may inhibit the optimal absorption of minerals such as iron and zinc.
Zinc and iron deficiency are reasonably common in those following a plant-based diet as absorption is limited by phytic acid..16 It's vital that those following a plant-based diet focus on consuming iron and zinc rich foods as well as soaking legumes, nuts, seed, and grains before cooking to reduce their phytic acid content. 17
High levels of soy intake can affect ovarian function.
Overconsumption of phytoestrogens like those found in soy foods, can hinder our body's ability to stabilise ovarian function by disrupting the signal to the ovaries to ovulate. 17
A retrospective cross-sectional study found that women consuming high consumption of soy (25% high than a standard western diet) were 13% more likely to have never been pregnant. This shows correlation, not causation. Moderation is key.
Inadequate DHA (Docosahexaenoic Acid)
A plant-based diet that doesn’t include seafood, fish and eggs may not provide enough DHA. DHA is a long chain fatty acid, which is part of the omega-3 family. DHA is crucial for cell integrity, brain and visual development of the fetus. DHA is particularly important in the third trimester when the foetal brain accumulates ~60mg of DHA/kg, per day.18
Try supplementing with algae oil, a vegan source of DHA to meet your requirements.
Absent in amino acid glycine
Conditionally essential amino acid glycine is absent in a plant-based diet. It is termed “conditionally essential” because the body can make it from choline, serine, hydroxyproline, and threonine. Animal skins and cartilage are good sources of glycine, so foods like bone broth and stews are excellent sources. Glycine provides methyl donors for DNA methylation and protein synthesis and has critical role of balanced nutrient supply through the placenta as well as playing an essential role in collagen synthesis.
No preformed vitamin A.
Preformed Vitamin A is only found in animal foods.
Our bodies can convert beta-carotene, which is plant-derived, to active vitamin A (retinol). Though everybody's genetic make-up is different and SNPs (single nucleotide polymorphisms), may determine a person's effectiveness in converting beta-carotene into retinol. 19
Vitamin A is essential for immunity health and eye development for the fetus. Following a Mediterranean diet will increase the likelihood of achieving adequate Vitamin A. 20 Vitamin A profoundly influences the differentiation of tissues throughout the body, and a deficiency may fail to develop sufficient stores in the offspring and be vulnerable to a vitamin A deficiency. 21
Conclusion
Regardless of your dietary choice, animal products or not, careful nutritional planning with targeted and personalised supplementation to meet your requirements is vital.
Approach your nutritionist to tailor your dietary needs for optimal fertility and to support a healthy pregnancy.
References
1. Chavarro, J. E., Rich-Edwards, J. W., Rosner, B. & Willett, W. C. A prospective study of dairy foods intake and anovulatory infertility. Hum. Reprod. 22, 1340–1347 (2007).
2. Cueto, H. T. et al. Folic acid supplementation and fecundability: a Danish prospective cohort study. Eur. J. Clin. Nutr. 70, 66–71 (2016).
3. Panth, N., Gavarkovs, A., Tamez, M. & Mattei, J. The Influence of Diet on Fertility and the Implications for Public Health Nutrition in the United States. Front. Public Health 6, 211 (2018).
4. Showell, MG, Mackenzie‐Proctor, R, Brown, J, Yazdani, A, Stankiewicz, MT & Hart, R. Antioxidants for male subfertility. Cochrane Database Syst. Rev. (2014) doi:10.1002/14651858.CD007411.pub3.
5. Arvizu, M. et al. Fat intake during pregnancy and risk of preeclampsia: a prospective cohort study in Denmark. Eur. J. Clin. Nutr. (2018) doi:10.1038/s41430-018-0290-z.
6. Gomez Arango, L. et al. Contributions of the maternal oral and gut microbiome to placental microbial colonization in overweight and obese pregnant women. Sci. Rep. 7, (2017).
7. Zimmermann, M. B. Iodine deficiency in pregnancy and the effects of maternal iodine supplementation on the offspring: a review. Am. J. Clin. Nutr. 89, 668S-672S (2009).
8. Iodine Supplementation During Pregnancy and Lactation. https://www.nhmrc.gov.au/about-us/publications/iodine-supplementation-pregnant-and-breastfeeding-women#block-views-block-file-attachments-content-block-1 (2009).
9. Vanegas, J. C. et al. Soy food intake and treatment outcomes of women undergoing assisted reproductive technology. Fertil. Steril. 103, 749-755.e2 (2015).
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11. Sharara, F. I., Seifer, D. B. & Flaws, J. A. Environmental toxicants and female reproduction. Fertil. Steril.70, 613–622 (1998).
12. Cariati, F. et al. “Bisphenol a: an emerging threat to male fertility”. Reprod. Biol. Endocrinol. 17, 6 (2019).
13. Ziv-Gal, A. & Flaws, J. A. Evidence for bisphenol A-induced female infertility: a review (2007–2016). Fertil. Steril. 106, 827–856 (2016).
14. Boeke, C. E. et al. Choline Intake During Pregnancy and Child Cognition at Age 7 Years. Am. J. Epidemiol. 177, 1338–1347 (2013).
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16. Foster, M., Chu, A., Petocz, P. & Samman, S. Effect of vegetarian diets on zinc status: a systematic review and meta-analysis of studies in humans. J. Sci. Food Agric. 93, 2362–2371 (2013).
17. Jefferson, W. N. Adult Ovarian Function Can Be Affected by High Levels of Soy. J. Nutr. 140, 2322S-2325S (2010).
18. Gould, J. F. et al. Assessing whether early attention of very preterm infants can be improved by an omega-3 long-chain polyunsaturated fatty acid intervention: a follow-up of a randomised controlled trial. BMJ Open 8, e020043 (2018).
19. Leung, W. C. et al. Two common single nucleotide polymorphisms in the gene encoding beta-carotene 15,15’-monoxygenase alter beta-carotene metabolism in female volunteers. FASEB J. Off. Publ. Fed. Am. Soc. Exp. Biol. 23, 1041–1053 (2009).
20. Hanson, M. A. et al. The International Federation of Gynecology and Obstetrics (FIGO) recommendations on adolescent, preconception, and maternal nutrition: “Think Nutrition First”#. Int. J. Gynecol. Obstet. 131, S213–S253 (2015).
21. Ross, A. C. & Gardner, E. M. The function of vitamin A in cellular growth and differentiation, and its roles during pregnancy and lactation. Adv. Exp. Med. Biol. 352, 187–200 (1994).