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  • Writer's pictureJen Walpole

Plant-based Diets When Trying To Conceive

The Mediterranean diet, which is predominantly plant-based comes out on top for supporting male and female fertility. However, it does still contain fish, dairy and meat so for those that are strict vegan, follow a mostly vegetarian diet or consume very few animal products, it’s really important to consider the key nutrients that might be low and may need additional supplementation and focus. Whilst some people may thrive on a strict vegan diet, others will not. Working 1:1 with a nutritional therapist would be beneficial to ensure this is the right choice for you and that your individual requirements are met.


Adequate dietary protein is essential to support rapid growth and development during pregnancy. Amino acids are the building blocks of proteins, and the body requires 20 of them to function properly. Nine of these are essential which means they must be obtained exclusively through the diet and include tryptophan, threonine, lysine and methionine. If we look at just these four in isolation, the richest sources are obtained from animal products, however, there are some key plant-based foods that offer smaller amounts. These include oats, nuts, seeds, tofu, quinoa, lentils, beans, edamame, green peas, spirulina, wholewheat bread and dark chocolate. One study concluded that increasing plant-based protein was positively correlated with better fertility outcomes compared to those that increased animal protein. The key here is to ensure you are obtaining a variety of these foods every single day as those on a plant-based diet will have to eat larger amounts to meet requirements. In addition, protein requirements increase by 6g per day from the first trimester.


Iron intake from food and supplements in early pregnancy is shown to be directly correlated with birthweight. Iron may be defined into two categories, haem-iron and non-haem iron. Whilst haem-iron is obtained from animal products, those on a plant-based diet will need to ensure they include non-haem iron from foods, such as lentils, beans, leafy greens like spinach, nuts, seeds and wholegrains. However, what some might not realise is that this form of iron is harder to absorb and utilise by the body. This alongside increased requirements during pregnancy of at least 10mg extra per day, can mean that vegans or vegetarians may be deficient. I would advise checking your stored iron (ferritin) levels ahead of conception so that if supplementation is required, you can seek this out. Adding vitamin C to non-haem iron foods can help to increase absorption so pair your lentils or spinach with some lemon juice.


This often-overlooked mineral is required for the production of thyroid hormones, which regulate most essential processes in the body and must be optimal for healthy pregnancy. Fish, seafood and dairy are some of the most common sources of iodine in the typical western diet. The richest plant-based source of iodine are seaweeds such as wakame, nori and kombu. As these are not as common in the western diet, deficiency risk is higher in vegans and vegetarians with one study reporting 80% of vegans as deficient. Dried seaweed can be purchased easily and should be added to dishes regularly to help support healthy iodine levels in vegans or vegetarians. It would also be a good idea to check thyroid function by arranging a full thyroid panel privately through a nutritionist.


B12 is found naturally in meat and animal products, which means it is essential for vegans to obtain this exclusively from supplementation. The prevalence of B12 deficiency in vegans is especially high with strong evidence to supplement in both vegan and vegetarian diets. Within one study, 62% of vegetarian pregnant women were found to be deficient. Lower B12 levels during pregnancy are associated with increased risk of preterm birth.


Another nutrient that comes predominantly from animal sources, choline is essential during pregnancy and naturally requirements increase. Vegetarians can obtain choline from eggs, but those following a vegan diet should ensure they increase their intake of beans, green peas and green leafy veg like broccoli as well as consider additional supplementation during pregnancy, which has been shown to improve pregnancy outcomes in studies.

Omega 3

Omega 3 is an essential fatty acid that is vital for foetal brain development and is positively associated with improved semen quality and embryo implantation. The active forms of Omega 3 are docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), which are only found in oily fish and algae oil. ALA (alpha-linolenic acid) is the form more commonly consumed on plant-based diets that are rich in seeds such as flax, chia and hemp seeds but must be converted into the active forms. Therefore, it is advisable to supplement a good quality omega 3 with suitable levels of EPA and DHA.

In summary, vegan, vegetarian or diets low in animal products are often depleted of key nutrients required for healthy pregnancy outcomes. That being said, consumption of a varied, whole foods vegan diet that is rich in a variety of plant-based protein, fruits and vegetables, wholegrains and includes supplementation of key nutrients can be a healthy choice for some people. Vegetarians may still require additional supplementation but can obtain some of the key nutrients from dairy and eggs. For those that consume low animal products and are open to increase this, it is advisable to do so, in line with the Mediterranean diet principles to optimise nutritional status when trying to conceive and during pregnancy.

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