Posted on March 14th, 2022by Dara Godfrey, RDin Nutrition

Vegetarians or Vegans - What to Consider When Trying to Conceive

I get asked almost daily whether a vegetarian or even vegan diet can help increase a woman’s chances of becoming pregnant. It sounds like a reasonable diet – one filled with an abundance of vegetables, whole grains, nuts, seeds, beans and legumes. Both vegetarians and vegans choose to avoid eating meat and fish, whereas vegans also avoid consuming any products that come from an animal including diary and eggs (and sometimes honey). A plant-based diet has the potential to provide many of vitamins and minerals that are essential for optimal fertility and ultimately for pregnancy. But is it the ideal meal plan to help increase your chances of pregnancy?

It is widely accepted that what a mother eats prior to conceiving and during pregnancy can help lay the foundation for healthy development of her baby. Let’s delve deeper into the potential benefits and potential risks of consuming a vegetarian or vegan diet.

Potential benefits of consuming a vegetarian/vegan diet:

  • Vegetables, especially leafy greens, are nutritional powerhouses and are particularly high in folate (crucial for the prevention of neural tube defects). Many vegetables are also abundant in vitamin C, beta carotene, B-vitamins, vitamin K and fiber.
  • Vegetarian diets that include eggs and dairy contain complete proteins meaning that they contain all of the nine essential amino acids that are body does not naturally produce. For both vegans and vegetarians, soybeans, quinoa and buckwheat also contain all the 9 amino acids.
  • The Harvard Nurses Study reported that lower animal protein intake did help reduce ovulatory infertility.
  • Other research has shown that consuming 5% of total energy intake as vegetable protein (rather than animal protein), was associated with a more than 50% lower risk of ovulatory infertility. (1)
  • Research has shown that plant-based diets are linked to lower rates of type 2 diabetes, heart disease, hypertension, some cancers and obesity. (2)

Potential risks/concerns of consuming a vegetarian, and especially a vegan diet:

  • Protein may be the weak link as it relates to overall health, fertility and pregnancy. As proteins are the building blocks of human life, it is crucial to consume a constant protein supply to help with a baby’s development as well as to one’s uterus and surrounding tissues. Many vegetarian protein sources are considered ‘incomplete’ as they are lacking in some of the essential amino acids.
  • Although some vegetarian and vegan foods contain complete proteins (eggs, dairy, tofu, quinoa, etc.), they may not contain as much protein, per serving, as animal protein. This means that one requires larger quantities of these foods to consume adequate daily protein.
  • In order for vegans or vegetarians to obtain enough total daily protein often requires eating a high carbohydrate diet, as many whole food plant proteins are also naturally high in carbohydrates (beans, legumes and whole grains). Overall, vegetarian women, on average consume more carbohydrates than non-vegetarians. (3) This may not be ideal for overall blood sugar stabilization.
  • Many essential nutrients that are important for conception and pregnancy are challenging to obtain from a vegetarian or vegan diet. They may require additional supplementation. These include:
    • Vitamin B12 – plays a vital role in fetal development and found exclusively in animal protein (except for a little fortification in nutritional yeast). Without adequate B12, the risk of miscarriage, neural defects and preterm delivery go up. (4)(5)
    • Choline – crucial for fetal brain development, helps prevent neural tube defects and is important for placental function. (6)
      Although choline is found in egg yolks, vegan sources are less concentrated in choline.
    • DHA – the most important form of omega-3 fats for pregnancy. DHA aids in fetal brain and eye development. Plant sources of omega-3’s come in the form of ALA. Our bodies inefficiently convert ALA to DHA. Although more expensive, algal oil (made from marine algae) shows a promising alternative. Studies thus far have suggested that the bioavailability is comparable to fish/krill DHA sources. (7)
    • Iron - a risk in developing iron-deficiency anemia, which can negatively impact ones fertility and potential pregnancy. Heme iron is only found in animal foods and can be absorbed more efficiently than non-heme iron, which is found in plant foods.
    • Zinc – most zinc in the average American diet is obtained from animal products. Similar to iron, many of the plant foods that contain zinc are also high in inhibitors of zinc absorption (such as phytic acid). Zinc deficiency has been linked to higher miscarriages, preterm delivery as well as neural tube defects. (8)
    • Preformed Vitamin A (retinol) – can help with fetal growth and development and deficiency can lead to serious malformations. (9) Plants do not contain true preformed vitamin A, but rather carotenoids, which are not as effectively absorbed.
    • Vitamin K2 – important for a baby’s skeletal development and is predominantly found in fatty-animal foods (like full fat dairy, eggs and liver). It is found in natto, a fermented soybean product that is found predominantly in Asia.
    • Glycine – an essential amino acid during pregnancy (meaning it must be obtained through one’s diet) for a baby’s development as well as for a mother’s health during pregnancy. (10)
  • Supplementation can only provide so much in terms of vitamins and minerals. Many nutrients found in animal foods are not available in supplemental form and their vegetarian supplemental alternatives are not as easily absorbed.
  • Many plant-based foods are highly processed ‘foods’ that happen to be made from plants. Plantain chips, ‘veggie’ chips, fake ‘meat’ are just some of the highly processed plant-based foods.

Clearly, there are real arguments for and against a vegetarian or vegan diet when trying to conceive. In my professional opinion, I would suggest, at minimum, to try and introduce (or prioritize) eggs and low-carb, higher fat dairy products (such as cheese and Greek yogurt), and choosing nuts, seeds and legumes over an abundance of grains to help ensure a nice balance between proteins and carbohydrates.

If a vegan or vegetarian diet is a non-negotiable, it is imperative to pay extra attention and optimize nutrient intake as well as supplementation. It is possible to have an overall complete and healthy diet, but it does takes extra focus and constant dedication to ensure a well-rounded diet (couldn’t we say the same for ALL types of eating plans?!). Working with a dietitian and doctor to create a balanced meal and supplementation plan is recommended.

(1) Chavarro, Jorge E et al. “Protein intake and ovulatory infertility.” American journal of obstetrics and gynecology vol. 198,2 (2008): 210.e1-7. doi:10.1016/j.ajog.2007.06.057
(2) Melina V, Craig W, Levin S. Position of the Academy of Nutrition and Dietetics: vegetarian diets. J Acad Nutr Diet. 2016;116(12):1970-1980.
(3) Janelle, K. Christina, and Susan I. Barr. “Nutrient intakes and eating behavior see of vegetarian and nonvegetarian women.” Journal of the American Dietetic Association. 95.2 (1995): 180-189.
(4) Molloy Anne M et al. “Efects of folate and iamin B12 deficiencies during pregnancy on fetal, infant and child development.” Food & Nutrition 29. Supplement 1 (2008): 101-111.
(5) Rogne, Tormotd, et al. “Associations of Maternal Vitamin B12 Concentration in Pregnancy With the Risks of Preterm Birth and Low Birth Weight: A Systematic Review and Meta-Analysis of Individual Participant Data.” American Journal of Epidemiology (2017).
(6) Zeisel SH. Nutrition in pregnancy: the argument for including a source of chiline. Int J Womens Health. 2013;3;5193-195.
(7) Lane K, Derbyshire E, Li W, Brennan C. Bioavailability and potential uses of vegetarian sources of omega-3 fatty acids: a review of the literature. Crit Rev Food Sci Nutr. 2014;54(5):572-579.
(8) Wang, Hua, et al. “Maternal zinc deficiency during pregnancy elevates the risk of fetal growth restriction: a population-based birth cohort study.” Scientific reports 5 (2015).
(9) Solomons NW. Viramin A and carotenoids. In: Shils ME, Olson JA, Shike M, Ross AC, eds. Modern Nutrition in Health and Disease. Baltimore: Lippincott Williams & Wilkins; 1999:3050327.
(10) Lewis, Rohan M., et al. “Low serine hydroxymethyltransferase activity in the human placenta has important implications for fetal glycine supply. “ The Journal of Clinical Endocrinology & Metabolism 90.3 (2005): 1594-1598.

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