Vegan-vegetarian diets in pregnancy: danger or panacea? A systematic narrative review

Abstract

Background Although vegan-vegetarian diets are increasingly popular, no recent systematic reviews on vegan-vegetarian diets in pregnancy exist.Objectives To review the literature on vegan-vegetarian diets and pregnancy outcomes.Search strategy PubMed, Embase, and the Cochrane library were searched from inception to September 2013 for pregnancy and vegan or vegetarian Medical Subject Headings (MeSH) and freetext terms.Selection criteria Vegan or vegetarian diets in healthy pregnant women. We excluded case reports and papers analysing veganvegetarian diets in poverty and malnutrition. Searching, paper selection, and data extraction were performed in duplicate.Data collection and analysis The high heterogeneity of the studies led to a narrative review.Main results We obtained 262 full texts from 2329 references; 22 selected papers reporting maternal-fetal outcomes (13) and dietary deficiencies (nine) met the inclusion criteria. None of the studies reported an increase in severe adverse outcomes or in major malformations, except one report of increased hypospadias in infants of vegetarian mothers. Five studies reported vegetarian mothers had lower birthweight babies, yet two studies reported higher birthweights. The duration of pregnancy was available in six studies and was similar between vegan-vegetarians and omnivores. The nine heterogeneous studies on microelements and vitamins suggest vegan-vegetarian women may be at risk of vitamin B12 and iron deficiencies.Author's conclusions The evidence on vegan-vegetarian diets in pregnancy is heterogeneous and scant. The lack of randomised studies prevents us from distinguishing the effects of diet from confounding factors. Within these limits, vegan-vegetarian diets may be considered safe in pregnancy, provided that attention is paid to vitamin and trace element requirements.

Maternal Diet and Nutrient Requirements in Pregnancy and Breastfeeding. An Italian Consensus Document

“…The inclusion of milk and eggs is associated with the adequate supply of nutrients to pregnant women, while the exclusion of all animal foods makes the vegan diet likely inadequate in this life period, if not properly integrated. A systematic review of the literature highlighted an increased risk of iron and vitamin B 12 deficiency and low birth weight in association with vegetarian or strictly vegan diets, despite the absence of adverse effects for the fetus [79]. …”

Animal (De)liberation: Should the Consumption of Animal Products Be Banned?

“…Some studies have found that some vegans had inadequate intakes of B12, where particular concerns have been raised over the B12 status of older people due to their limited absorption capacity and of pregnant women due to their higher demands (Majchrzak et al 2006;Waldmann et al 2005;Donaldson 2000;ADA 2009;Piccoli et al 2015). This is not a reason to eat flesh, as B12 binds with the protein in animal foods, impeding absorption, which is precisely why older people are better off with vegan sources of B12 (Norris and Messina 2011, 31).…”

Vegetarian diet observed by pregnant women. Benefits and risks for mother and fetus

“…A low intake of saturated fats and large amounts of vegetables, fruits, whole grains, legumes, soy products, nuts and seeds are characteristic of vegetarian and vegan diets, causing lower cholesterol levels and better control of blood glucose. The Academy of Nutrition and Dietetics [27] notes that vegans need reliable sources of vitamin B12 from fortified foods or supplements, as confirmed by the study by Piccoli et al [28], suggesting nutritional deficiencies in pregnant women, mainly in iron, vitamin B12 and D and calcium intake. That is why it is important to present as reliable as possible knowledge and to continue improving people's state of consciousness of in both the positive and negative health effects of vegetarian diets [26].…”