The number of people following a largely vegan or plant-based diet is on the increase, and the numbers continue to increase year on year. It is estimated that a quarter of the UK population could be following a vegan or vegetarian diet by 2025.
Reasons for adopting a vegan diet can vary from individual to individual and includes environmental concerns, animal welfare concerns and health concerns. There are health benefits to reducing the amount of animal products we consume. However, by completely removing animal-based foods from a diet there is also an increased risk of developing certain nutrient deficiencies that could have a negative impact on fertility.
It is estimated that 1 in 7 couples will struggle to conceive naturally and, therefore, an understanding of the best dietary patterns and key nutrients essential to optimise reproductive health and promote conception is becoming increasingly important. There are undeniable benefits of a vegan diet when it comes to reproductive health: for example, a vegan diet is rich in both folic acid and the antioxidant nutrient vitamin C. However, these benefits must be weighed against a risk of developing specific nutrient deficiencies as a result of the complete avoidance of animal products.
Vegan Diet, Nutrient Deficiencies and Fertility
The two most common nutrient deficiencies experienced by those who follow a vegan diet are deficiencies in vitamin B12 and Iron. Vitamin B12 is only found in animal products, whereas the Iron present in vegetables and other plant foods is in a poorly absorbable form. A deficiency of either of these two nutrients could negatively impact chances of conceiving and maintaining a healthy pregnancy.
Iron deficiency results in reduced red blood cell production and can lead to a reduced supply of oxygen reaching the reproductive organs. Iron deficiency among women who avoid animal products is very common, in fact one study found that all women who didn’t consume animal products had some degree of iron deficiency. We also know that there is a relationship between reduced iron intake in women and ovulatory infertility (infrequent or irregular ovulation) and therefore a reduced chance of conception. Studies have found that up to a third of vegan males have depleted iron stores, and this deficiency can negatively impact sperm production, contributing to a lower quality and smaller number of sperm being produced.
Vitamin B12 Deficiency
A Vitamin B12 deficiency is very common in vegans, with one study finding that 78% of the vegans tested had inadequate B12 status compared to 0% of meat eaters. B12 plays a key role in DNA production, helping to produce high quality DNA. Conception is essentially the combining of DNA from a sperm and egg cell and the quality of this DNA is key in promoting conception, both naturally and in assisted conception. In women vitamin B12 deficiency has been found to have a relationship with infertility and miscarriage and one study found that women who had better B12 levels had better embryo quality during IVF. Similarly a good B12 status in men is known to improve sperm number, motility and quality. Therefore, a deficiency of B12 could negatively impact male fertility.
Dairy-free diets, iodine deficiency and female fertility
The consumption of dairy-free foods, such as dairy-free milk, cheese and ice-cream has become increasingly popular, even among those not following a vegan diet. However, dairy products represent the main dietary source of iodine and anyone following a dairy-free diet run the risk of developing an iodine deficiency.
Iodine is crucially important for women trying to conceive due to its role in the production of thyroid hormone, deficiency of iodine can cause thyroid hormone production to dip. Low levels of thyroid hormones can then have a negative impact on chances of conceiving and impact foetal development during pregnancy.
During gestation babies’ brain and nervous system development is reliant on thyroid hormones, and iodine deficiency during pregnancy is linked to learning difficulties and lower IQ in offspring. Iodine requirements in pregnancy increase by around 50% because of the importance of thyroid hormone production during this time and unfortunately women who follow a dairy-free diet when trying to conceive and pregnant are at high risk of iodine deficiency.
So, the known health benefits of a vegan diet must be balanced by the risks of developing iron, iodine and B12 deficiencies and the potential negative impact of these deficiencies for reproductive health. When trying to conceive it is important to screen for nutrient deficiencies so that appropriate changes can be made to ensure optimal nutritional status to support egg and sperm quality and increase chances of conception. With an understanding of nutrient status proper nutritional support such as supplementation or adjustment of dietary patterns can be undertaken.
How to promote and maintain reproductive health while following a vegan diet
1. A key first step is to have a comprehensive health check that will measure your status of these key nutrients and thyroid hormone levels. Knowing your levels will help you to make appropriate dietary and supplemental changes to optimise your reproductive health while trying to conceive and to help meet the increased nutritional demands of pregnancy.
2. If you are committed to following a vegan diet for animal welfare or environmental reasons then appropriate supplementation of vitamin B12, iron and iodine will be necessary throughout your fertility journey. Consult your healthcare practitioner or a qualified Nutritional Therapist to ensure you are using these supplements in the appropriate way and in adequate dosages.
3. To support absorption of Iron in a vegan diet aim to consume a vitamin C-rich food (or vitamin C supplement) alongside your Iron-rich vegetables. Vitamin C supports the absorption of the form of iron found in vegetables. So dress your spinach with lemon juice or eat tomatoes alongside your black beans.
4. When purchasing milk alternatives always opt for those that have been fortified with nutrients normally present in cow’s milk such as vitamins D, B12 and Calcium. If you avoid dairy because you find it hard to digest, try introducing some fermented dairy products into your diet such as live natural yoghurt or kefir.
5. If your motivation for adopting a vegan diet was to optimise your reproductive health, continue to maintain those positive dietary changes such as consuming an abundance of plant-based foods. However, reintroducing small servings of high quality animal products alongside these plant based foods will provide the optimum balance of nutrients to promote reproductive health. Consider having a serving of organic red meat once a week and have 6 organic eggs weekly, or seek the advice of a qualified nutritional therapist to help you achieve the optimum dietary approach.
Learn more about your fertility and nutrient status
Whether you’re just curious for the future, or actively trying to conceive, you can book a blood test directly via Melio, at a time that suits you.
A trained health professional at one of our partner clinics will perform the blood draw, and send the sample to one of our UKAS accredited labs. All test results are individually checked by one of our in-house doctors, who will also write you a personal medical report with any further advice and guidance you may need.
Learn more and order your Melio blood test by clicking on a product below, or use the chat button if you’d like talk to one of our specially trained advisors for more information.
Sanders TA. The nutritional adequacy of plant-based diets. Proc Nutr Soc. 1999 May;58(2):265-9.
Mahajani, Kamla, and Vibha Bhatnagar. Comparative Study of Prevalence of Anaemia in Vegetarian and Non Vegetarian Women of Udaipur City, Rajasthan. Journal of Nutrition & Food Sciences S3 (2015).
Chavarro JE, Rich-Edwards JW, Rosner BA, Willett WC. Iron intake and risk of ovulatory infertility. Obstet Gynecol. 2006 Nov;108(5):1145-52.
Pawlak R, Berger J, Hines I. Iron Status of Vegetarian Adults: A Review of Literature. Am J Lifestyle Med. 2016;12(6):486-498.
Tvrda E, Peer R, Sikka SC, Agarwal A. Iron and copper in male reproduction: a double-edged sword. J Assist Reprod Genet. 2015 Jan;32(1):3-16.
Bennett M. Vitamin B12 deficiency, infertility and recurrent fetal loss. J Reprod Med. 2001 Mar;46(3):209-12
Hynes KL, Seal JA, Otahal P, Oddy WH, Burgess JR. Women Remain at Risk of Iodine Deficiency during Pregnancy: The Importance of Iodine Supplementation before Conception and Throughout Gestation. Nutrients. 2019;11(1):172.
Moog NK, Entringer S, Heim C, Wadhwa PD, Kathmann N, Buss C. Influence of maternal thyroid hormones during gestation on fetal brain development. Neuroscience. 2017 Feb 7;342:68-100.