Many people choose to eat little meat, only eat fish, not to eat meat at all (vegetarians), or not to consume animal products of any kind (vegans). Often these diets are eaten for moral, environmental, or health reasons, yet concerns are often aired that these diets lack important vitamins. Many vegans and vegetarians are very nutrition conscious, and with a few exceptions, careful food choice appears to generally make up for the lack of certain nutrients in an all- or mostly-plant diet.
With pregnancy comes new concerns: namely deficiencies in iron, calcium, folate, and other vitamins become more pronounced, and have greater consequences. Low birth weights, neural tube defects, and a variety of other problems can arise from vitamin deficiencies during pregnancy, especially at early stages during which pregnancy may not yet be detected. Vegetarians and vegans often suffer increased risk of a couple of these deficiencies, for example iron.
Some vitamin deficiencies are largely unique to vegans and vegetarians. B-12 deficiency in particular is common to anyone eating little meat, even non-vegetarians. Symptoms of B-12 deficiency generally appear in infants in their first year of life and can include lethargy, failure to thrive, and a loss of previously established developmental skills, among other possible problems. Severe neurological problems can also result. Folate, another B vitamin, is of common concern for pregnant women because folate deficiencies can lead to fundamental neural problems. Interestingly, folate is generally easy to get appropriate levels of for vegetarians and vegans eating a healthy diet, and high folate can mask B-12 deficiency. Because the problems associated with maternal B-12 deficiency don’t usually appear until the first year of life, this is an important, and potentially overlooked concern for vegan and vegetarian women who are considering children.
Supplementation is the first approach generally suggested, and indeed seems to be effective in many cases. However, there are many examples in which dietary supplements are not as effective as people would like to believe, and in some cases they may even be harmful. Therefore in cases in which the effectiveness of supplements has not been directly studied (and pregnant women are generally not experimented on for obvious reasons) it might be safer to actually include foods in the diet that have important nutrients, obviating the need for supplementation. Secondarily, many people who avoid animal products may also wish to avoid artificially ‘enhanced’ foods, such as vitamin-enriched cereal grains or genetically-modified plants that have B-12 producing genes inserted. So, it may be important to consider true whole-food sources of important nutrients in which specific diets are low.
Interestingly, some foods atypical in the western diet, such as dried purple laver (nori), and fermented foods such as
tempe, already eaten by many vegans, include high levels of B-12. Nori is generally wrapped around sushi rolls (avoid the fish rolls if pregnant due to heavy metal and probably parasite concerns), but can also be eaten in salads, on sandwiches, or for the other Midwesterners out there, in hotdish!
TL;DR vegans and vegetarians may have a few extra things to think about when choosing to become pregnant, but they can be solved through appropriate prenatal care with supplementation, and ideally very carefully chosen and potentially atypical dietary items such as nori
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