Advice for Vegan Mothers-to-Be — Nine Months of Proper Nutrition
By Dina Aronson, MS, RD
Vol. 9 No. 12 P. 38
Must expectant women eat eggs, meat, and fish to ensure healthy offspring? Not necessarily. A vegan diet that recognizes all essential nutrients can do mother and baby a world of good.
People who follow a vegan diet do so for one or more reasons: ethical, environmental, nutritional, and/or religious. Vegans consume only plant foods—grains, vegetables, fruits, and legumes (and processed foods made from them)—and no meat, poultry, fish, eggs, or dairy products. For most vegans who become pregnant, the diet continues throughout pregnancy and lactation.
Pregnancy is a time of high metabolic and nutritional demands. All pregnant women should follow the recommended nutritional guidelines, which are essentially the same for vegans and nonvegans alike. With a little planning and good sense, women on a vegan diet can meet the increased energy and nutrient requirements of pregnancy.1
In light of recent negative press on vegan diets, dietitians need to examine the facts and make appropriate recommendations based on sciences. Over the past few years, there have been several tragic infant deaths due to malnutrition or neglect. In a couple cases, the families’ defense was that they were vegan. Unfortunately, this led to a widespread misconception that vegan diets are inappropriate or irresponsible for pregnant women and young children.
The fact is that the deaths were not caused by veganism; they were caused by malnutrition. Vegan diets, when followed with care, supply all the nutrients required for optimal health and development. Denying a weeks-old infant breast milk or commercial formula (the only foods acceptable for newborns) and providing only soy milk and apple juice, for example, is not a vegan diet.
There are relatively limited data on pregnancy outcomes for vegan vs. nonvegan women. A classic study from 1987 looked at the medical records of 775 vegan mothers living in a vegan community in Tennessee.2 The main observations were that the pregnancies were normal; the vegan diet did not affect birth weight; and those studied were health-conscious, received prenatal care, and took prenatal supplements. Furthermore, the researchers found that the rate of preeclampsia was significantly lower than that of the general population, with only one case among all 775 vegans.
Informal pregnancy outcome data (of 2,028 pregnancies) collected in the same community of vegans from 1970 to 2000 showed a lower-than-average C-section rate (1.4%), postpartum depression (1%), neonatal mortality (0.4%), maternal mortality (0%), and preeclampsia (0.4%), with no complications or negative outcomes higher than average.3
Some studies have reported lower birth weights of infants born to vegetarian and/or vegan women than those born to omnivorous mothers.4-6 In nearly all cases, these lower birth weights were found when the mothers followed restrictive vegetarian diets, such as macrobiotic diets.4,5 With such diets, there were also trends of low maternal weight gain and lower maternal intakes of calories and nutrients.4-6 These outcomes help dietitians understand what the true risks are and realize that a diet labeled as vegan does not necessarily mean deficient. However, any diet, no matter what its label, may be lacking the proper balance of energy and nutrients.
A vegan diet can actually be protective during pregnancy. Since vegans weigh less on average than omnivores, vegans may have fewer weight-related complications. Although no formal study has been conducted that compares gestational diabetes rates among vegans vs. nonvegans, it has been suggested that maternal diet may be an independent risk factor for gestational diabetes. One such risk factor is low fiber intake. Vegans are known to have a higher fiber intake level; thus, a vegan diet may play a role in protecting a pregnant woman from gestational diabetes.7
As mentioned previously, the incidence of preeclampsia also appears to be lower among vegans.2 This is perhaps related to the theory that preeclampsia risk is associated with a high fat and sugar consumption and low fiber intake; vegans generally follow a low-fat, low-sugar, and high-fiber diet.8 Finally, constipation is a common complaint in pregnancy. Higher fiber intakes of vegan women may help prevent constipation.
Most of the “avoid” or “limit” foods for pregnant women, such as mercury-containing fish, soft cheeses, sushi, undercooked meats, cold cuts, certain meats, and unpasteurized milk products, are automatically excluded on a vegan diet. The only vegan products pregnant women should avoid are sprouts and any raw produce that may not have been properly handled (such as a salad bar at a store whose staff doesn’t wash the vegetables properly). In addition, many experts recommend that women with a family history of food allergy avoid the offending food during pregnancy to reduce the risk of passing the allergy to the baby.
Vegans are given the same weight gain recommendations as other pregnant women. Little weight should be gained (less than 5 pounds) during the first trimester, with a gain of one or two pounds per week during the second and third trimesters. Over the nine months, average-weight women should gain 25 to 35 pounds; underweight women, 28 to 40 pounds; overweight women, 15 to 25 pounds; adolescents, 30 to 45 pounds; and women carrying twins, roughly 35 to 45 pounds. Of course, these are basic guidelines; ideal weight gain patterns should be assessed on an individual basis.9 Should weight loss occur during the first trimester (due to nausea/vomiting, increased activity, or loss of appetite), small, frequent meals should be encouraged to keep the weight to at least prepregnancy level. Weight loss or failure to gain in the second and third trimesters should be examined and treated by a medical team.
During the first trimester, caloric needs are generally the same as for nonpregnancy. During the second and third trimesters, an additional 200 to 300 calories per day (over prepregnancy estimated needs) are generally recommended. Since caloric needs increase only approximately 15% and nutrient needs increase up to 50%, a nutritionally dense diet in pregnancy is needed to meet nutrient needs within the caloric recommendations. Vegans should be counseled, just like all clients, that intake of low-nutrient foods such as candy and sweets should be limited.10
Women who find it challenging to meet energy needs should be counseled to choose nutritious foods with higher caloric density. Suggestions include milk shakes (based on fortified vegan milks such as soy, rice, almond, or hemp), nuts and nut butters, dried fruits, natural fats such as avocado and olives, soy products, and bean dips. Small, frequent meals and snacks can also help increase food intake.10
Two hundred to 300 calories may sound like a lot of extra food to pregnant women; it is not uncommon for them to overcompensate and “eat for two.” Providing some vegan examples such as the following may help them visualize this amount of food:
• one slice of whole wheat bread with 2 tablespoons of peanut butter = 250 calories;
• 8 fluid ounces of fruit juice, five crackers, and 1 ounce of soy cheese = 215 calories;
• 8 fluid ounces of fortified soy milk and 1/4 cup of trail mix = 255 calories; and
• one orange and 1 ounce of almonds = 230 calories.
To allow for increased blood volume and metabolic demands, pregnant women need at least 300 milliliters (approximately 10 fluid ounces) of additional fluid intake over normal recommended intake.11 Some pregnant women need reminders to drink enough, especially in the hotter months and as pregnancy progresses. Dehydration may lead to early labor because the hormones that stimulate contractions will be in higher concentrations in a body that is not well hydrated.
Protein needs are not vastly higher during pregnancy. The recommendation is approximately 10 more grams per day above nonpregnant needs for a total of roughly 60 grams— perhaps a bit more, depending on the woman’s size and exercise level. Most vegan women consume this much even before pregnancy, so rarely is this increase an issue.
High-protein plant foods include beans, lentils, and peas; nuts and nut butters; seeds and seed butters; and soy foods. Foods moderate in protein include whole grains and many vegetables. Many are surprised to learn that grains and vegetables have protein. A cup of brown rice, for example, has 9 grams, while quinoa tops the grain charts at 12 grams per cup. A cup of cooked spinach has 8 grams of protein, and a medium baked potato has 3 grams.
For women having trouble meeting protein needs, supplements (powders based on rice, soy, or hemp) are readily available at health food stores. They can be blended into beverages, soups, casseroles, mashed potatoes, and other foods. For most pregnant vegans, however, protein supplements are unnecessary.
Essential Fatty Acids (EFAs)
A woman’s diet affects the EFA status of her developing infant during pregnancy. Sanders et al reports greater proportions of omega-6 fatty acids and lower proportions of omega-3 fatty acids in vegetarians compared with omnivores. Indeed, vegans tend to consume excess omega-6 fatty acids but only one half of the necessary omega-3 fatty acids.12 Docosahexaenoic acid (DHA) is a necessary part of cell membranes and is important for brain development and vision. Low omega-3 status in pregnancy might lead to insufficient conversion of alpha-linolenic acid (ALA) to DHA. Plus, excess omega-6 fats further reduce conversion.
Pregnant vegans should be advised to consume a reliable source of omega-3 fatty acids on a daily basis. ALA requirements are approximately 4 to 5 grams per day (nearly double the amount of nonpregnancy needs). Good vegan sources of these fats include flaxseeds and their oil, hemp seeds and their oil, leafy green vegetables, soy products, soy milk fortified with DHA, walnuts, and rapeseed (canola) oil. As a benchmark, 2 teaspoons of flaxseed oil or 2 tablespoons of canola oil will provide sufficient omega-3 fatty acids for most pregnant women.13 But because it may be challenging to meet these needs, a DHA supplement providing 200 to 300 milligrams per day is often recommended for pregnant vegans.
Vitamin B12 intake and status have been shown to be lower in pregnant women following a plant-based diet than those following a typical Western diet.14 Since B12 is found naturally in animal foods, it is to be expected that vegans who do not supplement with B12 will have a lower intake and therefore lower status. It is imperative that pregnant women achieve the recommended intake of 2.6 micrograms per day during pregnancy. For vegans, B12 can come from fortified foods, a supplement, or both. Common B12-fortified foods include breakfast cereals, soy and other plant-based milks, nutrition bars, meat substitutes, and Red Star Vegetarian Support Nutritional Yeast. Some people mistakenly believe—and some popular press pieces claim—that plant-based foods such as tempeh, sprouted beans, sea vegetables, and algae are reliable sources of B12. This is not the case; in fact, these foods may contain B12 analogs, which actually block vitamin B12 absorption.15
Folic acid deficiency, which increases the risk of neural tube defects, has not been identified as an issue in pregnant vegan women. This may be because vegetarians typically consume more vegetables, which are high in folic acid, than omnivores.16 Pregnant women need 600 micrograms per day. Especially beneficial sources are orange juice, beans and lentils, leafy green vegetables, fortified breakfast cereals, whole grains, and products made with enriched wheat flour. So, a well-nourished vegan is already at a nutritional advantage when it comes to folic acid. Nonetheless, it wouldn’t hurt a pregnant vegan to take an oft-recommended daily multivitamin with 400 to 800 micrograms of folic acid.
Vitamin D is not normally found in vegan foods (or in most animal products, for that matter). The Recommended Dietary Allowance (RDA) for pregnancy—5 micrograms (200 international units [IU])—is the same as for nonpregnant women, but achieving this level is still very important during pregnancy. Many researchers argue that the RDA is set too low; more can be taken safely as the upper limit has been set at 50 micrograms (2,000 IU).
Vitamin D status of vegans has not been extensively studied and varies based on sunlight exposure and dietary choices. While it is true that vitamin D can be made from exposure to the sun, the modern lifestyle of work and leisure spent mostly indoors and the use of sunscreens to prevent skin cancer do not promote sufficient ultraviolet light exposure for adequate vitamin D synthesis.15
Pregnant vegans should take a vitamin D supplement of 5 to 10 micrograms (200 to 400 IU) daily. Many fortified foods contain vitamin D, such as soy milk, breakfast cereal, orange juice, and bars. Note that in most cases, vitamin D3 is derived from animal sources, so vegans will choose the D2 form. And since it appears that D2 is not as well absorbed as the D3 form, vegans should strive for the higher end of the recommended range (400 IU).
Pregnant women have the highest need for iron of all populations despite the fact that menstruation ceases during pregnancy. The substantial demand is due to increased blood volume, fetal development, and the possibility of blood loss during delivery. Iron needs increase as pregnancy progresses, and pregnancy’s strong positive effect on iron absorption is an important physiological adjustment. Maternal iron stores typically meet the fetus’ needs, so that even infants born to iron-deficient mothers are unlikely to be anemic unless the mother’s anemia is severe. This is not to say that deficiency will not put the fetus at risk; adequate iron intakes and good iron status during pregnancy are important to minimize outcome risks of both mother and fetus.15
Supplements are generally recommended to meet the iron needs of pregnancy (27 milligrams per day for nonvegetarians starting at week 12 of gestation). The Institute of Medicine recommends that vegetarians consume 1.8 times the regular RDA for iron for all populations. Given that the RDA for vegans during pregnancy (48.6 milligrams per day) actually exceeds the upper limit for safety (45 milligrams per day) set by the same organization, it is important to assess vegetarians’ iron needs on an individual basis. Whether this rather high intake of iron has been shown as truly necessary in cross-cultural studies of vegetarians is a matter of debate; furthermore, supplemental doses of 38 to 65 milligrams of iron per day may reduce zinc and copper absorption.
A carefully planned, iron-rich vegan diet can provide adequate iron to the growing fetus and keep maternal iron stores optimal throughout pregnancy. Pregnant women who do not take iron supplements should be carefully monitored throughout pregnancy.
As iron supplements often cause gastrointestinal discomfort and constipation, options include a liquid supplement, a form other than iron sulfate (eg, glycinate, fumarate, and gluconate), and weekly rather than daily supplementation.
The best vegan food sources of iron are spinach and other leafy greens, dried fruits, baked potatoes, beans and peas, tofu, seeds, nuts, soy milk, and fortified breakfast cereals. Since vegan foods feature nonheme iron, pregnant vegans are advised to maximize iron absorption by consuming a source of vitamin C with iron-rich foods and avoiding foods high in phytate and tannins with high-iron foods.
The RDA for calcium—1,000 milligrams—does not increase for pregnancy, nor is there a separate RDA for vegetarians. (Pregnant adolescents need 1,300 milligrams.) Calcium absorption is increased in pregnancy, typically resulting in a positive calcium balance. Pregnant vegans should strive for the RDA via foods and/or supplements. Calcium-fortified foods (soy/nut/rice/hemp milk, juice, cereals, waffles, and bars), calcium-set tofu, beans, sesame seeds, figs, nuts, leafy greens, and supplements are all easy ways to get 1,000 milligrams. Note that most prenatal supplements fail to provide 100% of calcium because calcium takes up a lot of space in a pill. This turns out to be a good thing because no more than 500 milligrams of calcium should be taken at once, as this is the maximum that can be absorbed per dose.17
Women who take supplements and use fortified foods should be warned not to overdo—just one bowl of Total cereal can provide a day’s worth of calcium. The upper limit for safety is 2,500 milligrams per day.
During pregnancy, the RDA for zinc jumps from 8 to 11 milligrams and from 9 to 12 milligrams for adolescents. Many women in the United States, both omnivores and vegans, do not consume diets that meet the RDA for zinc during pregnancy. Several studies have examined vegetarians’ zinc status during pregnancy, and no significant differences were found when compared with their omnivore counterparts.15 Since zinc status is difficult to assess and zinc is an essential nutrient for growth and development, pregnant vegans should emphasize good food sources of zinc, such as legumes, nuts, and whole grains. A good prenatal supplement will provide approximately 15 milligrams of zinc.
Pregnant women who follow a well-planned, balanced vegan diet may still wish to use a prenatal vitamin to fill in any nutritional gaps. There are many vegan brands available from online stores and health food stores. Vegan DHA supplements are derived from algae rather than fish. (There are at least two vegan brands.)
Pregnant vegans are often told by well-meaning family, friends, and healthcare professionals that they are putting themselves and their baby at risk by choosing to be vegan. These women need our support, expertise, and guidance. Good science and thousands of cases have proven that it is certainly possible—and not difficult—to be a pregnant vegan and grow a healthy, thriving baby.
— Dina Aronson, MS, RD, is a nutrition consultant, a freelance writer, and a speaker specializing in dietetics-related technology and vegetarian nutrition.
Sounds Like a (Meal) Plan
An appropriate vegan meal plan for pregnancy loosely follows this guide from Becoming Vegan: The Complete Guide to Adopting a Healthy Plant-based Diet by Brenda Davis, RD, and Vesanto Melina, MS, RD:
• Bean and bean-alternate group: 3 to 4 servings per day. (A serving is approximately 1/2 cup cooked beans or 3 ounces tofu/tempeh, 1 ounce nuts/seeds, 2 tablespoons nut butter, or 1 cup soy milk.)
• Grain products (opt for at least one half from whole grains): 7 to 11 servings per day. (A serving is approximately 1/2 cup grain or one slice bread.)
• Vegetables: 4 or more servings. (A serving is approximately 1/2 cup cooked or 1 cup raw.)
• Fruits: 3 to 4 servings. (A serving is 1 medium fruit or 1/2 cup sliced.)
Within these choices, be sure to include 6 to 8 servings of calcium-rich foods, 2 servings of essential fatty acid sources, and reliable sources of vitamin D and B12.
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15. Messina V, Mangels R, Messina M. The Dietitian's Guide to Vegetarian Diets: Issues and Applications. 2nd ed. Sudbury, MA: Jones and Bartlett Publishers; 2004.
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17. Dietary Supplement Fact Sheet: Calcium. Office of Dietary Supplements, National Institutes of Health Clinical Center, National Institutes of Health. Available here.