Human Health

Restricting animal source foods puts the young at risk

Paediatric guidance and parental responsibility are crucial in the case of strict vegetarian diets. Animal foods provide key nutrients, such as vitamin B12, iron, EPA/DHA, and choline, the absence of which could seriously compromise the health and well-being of young children. Moreover, a low supply of these nutrients during pregnancy and lactation can lead to negative outcomes for infants. Deficiencies in essential nutrients can lead to serious health problems, including failure to thrive, anaemia, neuropathies, and cognitive impairment. Clinical case reports of children on strict vegetarian diets have shown severe health consequences, emphasizing the need for proper nutritional planning and monitoring. Professional associations worldwide caution against vegan and vegetarian diets for pregnant women, infants, children, and adolescents.

This article addresses the following five topics:

Animal source foods and malnutrition in the young
Maternal avoidance of animal source foods: why is it risky?
What is known from the medical literature?
Parental responsibility vs. paediatric guidance
Professional associations and authorities

Animal source foods and malnutrition in the young

The global situation of infant and child malnutrition is concerning. More than half of children under the age of five suffer from micronutrient deficiencies necessary for healthy development, and nearly a quarter of children are stunted. Stunting is influenced by various factors, including poverty-driven issues, poor intake of protein and micronutrients, and maternal nutritional status. The early childhood period, especially the first 1000 days, is crucial for development, and animal source foods play a significant role during this time. Undernutrition during early age can lead to irreversible damage, particularly concerning neural health. On the long term, this can have an adverse impact on education, lifelong achievement, economic productivity, and community outcomes. Micronutrient deficiencies and growth issues are still prevalent in various countries. For example, India faces significant micronutrient deficiencies, stunting, and wasting rates. In the West, strict vegetarian diets may also create a risk for suboptimal physical or cognitive development, while paralleling reduced bone mineral content, vitamin B-12 deficiency, and iron-deficiency anaemia.

Maternal avoidance of animal source foods: why is it risky?

Addressing infant health requires careful attention to maternal nutrition, particularly for women following restrictive vegetarian diets. Pregnant and lactating women have elevated nutritional needs, requiring various nutrients that are highly bioavailable in animal source foods. Maternal undernutrition can lead to alterations in growth trajectories and neurocognitive development. Deficiencies in iron, DHA, choline, iodine, and B12 are of particular concern.

Further reading (summary of the literature):

A global issue

Dealing with infant health also needs to factor in the maternal diet, as pregnant and lactating women have higher nutrient requirements due to foetal growth and milk production [Fewtrell et al. 2017]. Multiple micronutrients (vitamins B2, B12, and D, DHA/EPA, calcium, iron, iodine, zinc) can be critical during a maternal vegan diet [Richter et al. 2016]. Several of these micronutrients are involved in brain development and become particularly important in the third semester of pregnancy and the early neonatal period [Georgieff 2007; Zimmermann 2012; Kiely et al. 2021; Leonard & Kiely 2024]. Moreover, the role of some other crucial nutrients like choline is still being neglected [Robb et al. 2023]

This issue of maternal undernutrition needs particular attention in lower-income and culturally diverse countries, as most dietary recommendations for pregnant women derive from data obtained in high-income countries [Robb et al. 2023]. Anaemia, for instance, already affects 1/3 of the women of reproductive age [Nordhagen et al. 2020]. Among Indian preschoolers, stunting and wasting were associated with the vegetarian status of their mothers [Headey & Palloni 2020].

Data from high-income countries

Even in Europe, about 1/2 women of reproductive age have small or depleted iron stores, 10–32% are iron deficient, and 2–5% have iron deficiency anaemia; only 20–35% have sufficient iron stores to complete a pregnancy without supplementary iron [Milman et al. 2017]. Belgian data shows that iron status deteriorates in the third trimester of pregnancy, not only leading to 40% of women with too low serum ferritin overall, but also to 16% and 7% of iron-deficiency anaemia and tissue iron deficiency, respectively [Vandevijvere et al. 2013]. In Slovenia, about 30% and 10% of premenopausal women suffer from depleted and critically depleted iron stores, respectively [Lavriša et al. 2022]. In the US, the majority of women of child-bearing age does not meet adequate DHA and choline intakes, which play a role in infant neural health and brain and eye development [Wallace & Fulgoni 2017, Mun et al. 2019].

Nutritional outcomes of maternal undernutrition

Some consider strict vegetarian diets as 'totally inadequate' for pregnant and lactating women [Wagnon et al. 2005]. Newborns may be at an increased risk of small-for-gestational-age, involving lower birth weights and lower mean gestational weight gain [Tan et al. 2019; Avnon et al. 2020; Hedegaard et al. 2024]. Maternal undernutrition, due to veganism or otherwise, may potentially alter placental weight, nutrient transfer capacity, and foetal growth trajectories [Sebastiani et al. 2019]. In general, low intake of animal source foods can lead to a problematic status of key nutrients, such as iron, EPA/DHA [Burdge et al. 2017] or vitamin B12 [Specker et al. 1988, 1990; Renault et al. 1999; Bjørke Monsen et al. 2001; Koebnick et al. 2004], but not carnitine or B2 [Juncker et al. 2023]. Maternal undernutrition may also affect nutrient transfer via lactation. Vegan diets may increase the risk of vitamin B12 deficiency in pregnant women and infants, and decrease the iron stores evaluated by ferritin [Oussalah et al. 2021]. Breast milk from US women on a vegan diet tends to have more selenium but less iron and iodine than milk from omnivore women [Perrin et al. 2023]. If a pregnancy starts with low iodine stores, it can have consequences for neurodevelopment of the offspring; young vegan women of reproductive age should pay particular importance to using supplements or iodine-fortified foods [Groufh-Jacobsen et al. 2024]. The problem of maternal deficiencies may become more acute as vegetarianism and veganism become more widespread among pregnant women [Rashid et al. 2020].

Examples of specific nutrients include:

Iron: an increased risk of latent iron deficiency in newborns may be related to low meat intake during pregnancy, which may then affect myelination and neurocognitive development [Moraes Castro et al. 2020; McCarthy et al. 2022]. Iron deficiency at young age may result in an altered brain structure and an impaired development of immune, endocrine, and cognitive functions [Antonidis et al. 2015; Bailey et al. 2015; Kiely et al. 2021].
DHA: a low maternal status can affect the DHA status of newborn and breast-fed infants, with potential implications for short- and long-term neural development [Sanders & Reddy 1992; Innis 2008; Coletta et al. 2010; Sinclair et al. 2023]. Spanish vegan/vegetarian mothers tend to have low DHA levels in breastmilk, in addition to lower iodine [Ureta-Valesco et al. 2023]. In the US, however, DHA levels in breastmilk are rather low in general, and do not correlate well with dietary patterns [Perrin et al. 2019].
Iodine: Iodine requirements increase by 50% during pregnancy [Grossklaus et al. 2023]. Even a mild-to-moderate maternal iodine deficiency in the first semester can already have an impact on the production of thyroid hormones in the foetus, and thereby affect both neurological and physical development [Kiely et al. 2021; Grossklaus et al. 2023; Leonard & Kiely 2024]. In addition to being a concern during pregnancy, the problem of maternal deficiency can also arise during lactation, leading to inadequate iodine levels in breast milk [Andersson & Braegger 2022]. All this is of particular relevance for vegan mothers given that iodine is rather difficult to obtain from plants other than seaweed [Pawlak et al. 2023]. In Ireland, most women of childbearing age already do not meet the iodine recommendation set for pregnant women [McNulty et al. 2017], especially during summer [Nawoor et al. 2006], which could be further aggravated by changes to the current dairy practices.
Choline: levels in maternal milk are associated with better infant recognition memory, especially when paired with high DHA content [Cheatham & Sheppard 2015]. However, a maternal plant-based diet by itself is not necessarily a risk factor for low breast-milk choline [Perrin et al. 2020].
Vitamin B12: pre-dominantly vegetarian diets in some regions of the Global South, which are low in ASFs, may lead to vitamin B12 shortage in breastmilk, as found for a majority of Kenyan women (89% of cases) [McLean et al., 2007; Williams et al. 2016; Balehegn et al. 2019] and for 64% of exclusively breastfed infants of South-Indian women [Kadiyala et al. 2020]. In Nepal, being a vegetarian was associated with lower plasma levels of vitamin B12 during gestation [Schwinger et al. 2021]. Although B12 deficiency is a known pitfall of vegan diets that can be corrected by supplementation [Ureta-Valesco et al. 2023], many fail to supplement adequately [see elsewhere]. As a result, vitamin B12 deficiency remains one of the most serious complications of vegetarianism and its variants [Aguirre et al. 2019].
Calcium and vitamin D: vegetarianism and vitamin D deficiency in pregnant women can lead to gestational diabetes mellitus when severe [Teotia et al. 2021].

What is know from the medical literature?

Neonates and infants born to vegan, vegetarian, or macrobiotic mothers may experience reduced birth weight and various nutrient deficiencies, which can result in serious or irreversible pathological symptoms. The latter may include failure to thrive, hyperparathyroidism, macrocytic anaemia, neuropathies, psychosis, lethargy, spinal cord degeneration, cerebral atrophy, and optic neuropathies. Of particular concern is vitamin B12 deficiency, which can be life-threatening and may lead to impaired cognitive functions later in life. Additionally, strict vegetarian children may face vitamin D deficiencies, potentially leading to conditions like rickets. Numerous clinical case reports have documented that avoiding animal source foods can lead to harm in infants, children, and adolescents. Such reports are considered lower on the hierarchy of evidence, but they nonetheless raise serious concerns given their severity. Larger and more controlled studies looking into restrictive diets for vulnerable populations are limited due to ethical reasons.

Parental responsibility vs. paediatric guidance

The responsibility for ensuring a nutritionally suitable diet is primarily placed on the parents, but it has been argued that paediatricians need to be closely involved in monitoring and managing the diets of pregnant and lactating women, as well as their children, when following diets low in or devoid of animal source foods. Even with diligent supplementation, vegetarian diets may still put children at risk in the short and long term. It is recommended to seek expert advice and guidance when transitioning to a vegan diet in such cases. Children on a vegan diet may require various nutritional supplements to prevent deficiencies. Providing paediatric guidance to vegan parents can be challenging due to the philosophical beliefs associated with veganism and a distrust of family paediatricians. When parents reject intervention and a child's health is at serious risk, some have argued that legal consequences are necessary, and that such cases may have to be treated as child abuse.

Professional associations and authorities

Professional associations and authorities worldwide have issued warnings and caution against vegan diets, especially for vulnerable population groups such as pregnant and lactating women, infants, children, and adolescents. Notable exceptions are the position papers of the US Academy of Nutrition and Dietetics. They are to be interpreted with caution given the ideological and activist background of their authors. Warnings are based on the difficulty of attaining adequate nutrient supply through vegan diets in populations with elevated needs, which may lead to severe nutrient deficiencies and irreversible health consequences.

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