This is the transcript of the talk given by Reed Mangels, Ph.D., R.D., F.A.D.A. at the American Dietetic Association Annual Meeting and Exhibition, October 28, 1997, Boston, MA. This was part of a larger session called Plant-based Diets: Pregnancy Through Childhood.
Pregnancy, lactation, infancy, and early childhood are periods of nutritional vulnerability for both vegetarians and nonvegetarians. As nutrition professionals, we are aware that vegetarian diets are appropriate for women throughout pregnancy and lactation and for their infants. However, questions often arise on nutritional needs and how to meet these needs during periods of vulnerability. Today, I hope to address these issues.
slide -Studies of Vegetarian Pregnancy
What does recent scientific literature tell us about vegetarian pregnancies? Generally, it is reassuring. A number of studies of lacto-ovo vegetarians (vegs who use dairy products and eggs) have shown that maternal weight gain and infant birth weights were not significantly different from those of non-vegs. Similarly, two studies of vegan pregnancy, one in the US and one in Britain found birth weights to be similar to those of non veg women while the average weight gain of vegan women was slightly higher than that of the reference population. Vegans are vegetarians who use no animal products. There have been reports of low birth weights in infants of women following macrobiotic diets. These women appeared to have both low weight gain and low energy intakes. The macrobiotic diet is based largely on grains with smaller amounts of vegetables (especially sea vegetables), soups, and beans and is typically more restrictive than other types of vegetarian diets.
slide - Studies of Vegetarian Pregnancy, cont.
Additionally, anemia was no more common in vegans than in non-vegetarians during pregnancy and iron intakes of some pregnant vegetarians was close to the RDA even without supplements. A low incidence of preeclampsia has been reported in vegan women.
What should our priorities be when working with pregnant vegetarians? An important consideration in any pregnancy is adequate weight gain.
slide - Recommended Weight Gain in Pregnancy
[28-40 lbs for those underweight prior to pregnancy; 25-35 lbs for those of normal weight; 15-25 lbs for those overweight; at least 15 lbs for those quite overweight prior to pregnancy]
Weight gain recommendations for pregnancy apply to vegetarians. Vegetarians as a group tend to be leaner than omnivores and the vegetarian diet is commonly one which is low in fat and high in fiber, leading to a lower energy density diet, so some pregnant w omen may need advice on meeting calorie needs to sustain adequate weight gain. Energy rich foods such as nuts and nut butters, dried fruits, and soy products can help as can small frequent meals.
A common question for many people is protein intake in vegetarian pregnancy.
slide - beans (photo)
As I'm sure you're aware, sources of protein for vegetarians include legumes, grains, soy products, meat analogues, nuts and nut butters, seeds and seed butters, dairy products, and eggs.
slide - Protein in Pregnancy
The RDA calls for an increase in protein of 10 grams per day, for a total of 60 grams of protein daily. Even before pregnancy, it is not uncommon for lacto-ovo and vegan women to have protein intakes above this level. When additional calories are provided to support weight gain, protein intakes are frequently at or above recommended levels. Some years ago, a popular theory promoted eating combinations of plant proteins at each meal to insure adequate intake of essential amino acids. This is no longer considered necessary and with a mixed diet and adequate energy intake, there should be no need to be concerned about combining proteins.
Slide - canned beans(photo)
The next slide shows canned beans, a wonderful convenience food for pregnant women, not only are they simple to prepare and inexpensive, but they also are a good source of protein, iron, and zinc. Iron deficiency is no more common in vegetarian pregnancy than in non-veg preg but it does occur. Iron supps are commonly recommended as are iron rich foods like whole grains, dried beans, dark green leafy vegs, blackstrap molasses, tofu. A vitamin C source at the same meal enhances absorption of non-heme iron.
Slide - zinc in pregnancy
Zinc is a nutrient which needs to be emphasized in pregnancy. Several studies have examined zinc status in vegetarian pregnancy. In one study, vegetarians consumed slightly less zinc than did non-vegs but were not significantly different in terms of those zinc status indicators which were assessed. Another study found zinc intakes similar to those of non-veg. Bioavailability of zinc, in groups with high intakes of whole grains and legumes, is reduced due to the phytate which is found in these foods.
slide - whole grains (photo)
Fiber may also inhibit zinc absorption but since whole grains are higher in zinc than refined grains, the absolute amount of zinc absorbed may not be compromised from consumption of whole grains.
slide - nut butters (photo)
Zinc sources include nuts, dried beans, hard cheeses, wheat germ, fortified and whole grain cereals and pasta, sea vegetables, tofu, and miso. Many of these foods are also important sources of other nutrients. For example, dried beans, nuts and nut bu tters and soy products are good sources of protein and whole grains provide B-vitamins. So, by stressing key foods such as these to pregnant clients, more than one nutrient need can be met.
slide - calcium in pregnancy
[Dietary calcium intake does not appear to influence changes in maternal bone mass during pregnancy; maternal; adaptive responses include enhanced calcium absorption; provided dietary calcium intake is adequate prior to pregnancy, there is no need to increase intake during pregnancy; current adequate intake is 1300 mg for 14-18 yrs and 1000 mg for 19-50 yrs) In August, the National Academy of Sciences released new recommendations for dietary intakes of calcium and related nutrients. The next slide presents some of their comments related to calcium in pregnancy. It appears that if calcium intake is adequate prior to pregnancy, there is not an increased need for calcium in pregnancy. Of course, we must ascertain whether or not dietary calcium intake was adequate. In general, calcium intakes of lacto-ovo vegetar ian women are close to recommendations while those of vegans are lower. Therefore, it is important for vegan women to choose foods which can boost their calcium intake.
Slide - greens (photo)
Dark green leafy vegetables like kale, collard greens, mustard greens, turnip greens represent a highly bioavailable source of calcium.
Slide - soy foods (photo)
Tofu, prepared with calcium sulfate, provides calcium and is also a good source of protein and iron.
Slide -soy milks (photo)
Calcium fortified soymilks, rice milks, and orange juice are other excellent ways to meet calcium needs. This slide shows some soymilks and rice milks which are fortified with various nutrients such as calcium, vitamin D, vitamin B-12, and other nutrients. Nutrient content of soymilk varies so it is worthwhile to investigate the composition of products in your area.
Slide - Vitamin D in Pregnancy
Adequate vitamin D is necessary to promote maternal calcium absorption. Food sources of vitamin D include fortified cow's milk, fortified soy or rice milk, and fortified cereals. The National Academy of Sciences has these comments about vitamin D: Women who have regular sunlight exposure do not require vitamin D supplements; However, adequate exposure is difficult to define; If there is a question as to adequacy, dietary or supplemental vitamin D is needed to achieve an intake of 5 micrograms (200 IU) daily.
Slide - vitamin b-12 in preg
Vitamin B-12 is required by all cells which synthesize DNA including those of the nervous and hematopoietic systems. Thus, it is an essential nutrient for the developing fetus. In addition, maternal vitamin B-12 intake influences the level of vitamin B-12 stores in the infant. A regular source of vitamin B-12 is needed throughout pregnancy because of the possibility that only newly absorbed vitamin B-12 is transported across the placenta. As the slide shows, the RDA in pregnancy is 2.2 mcg per day. Food sources include fortified cereals, soymilk, meat analogues; Vegetarian Support Formula nutritional yeast; dairy products and eggs. Some foods such as tempeh and miso and sea vegetables have been promoted as sources of vitamin B-12. In reality, these are not reliable sources and may actually contain cobalamin analogues which can block absorption of true vitamin B-12 and may accelera te nerve damage.
So, some considerations in vegetarian pregnancy are weight gain, and adequacy of iron, zinc, calcium, vitamin D, and vitamin B-12 intakes.
Many of these same considerations apply in vegetarian lactation. While energy intake is less important, good sources of vitamin B-12, D, and calcium need to continue to be emphasized.
Slide - Recommendations for Nutrient Intake in Vegan Lactation
Low plasma vitamin B-12 levels have been seen in macrobiotic lactating women and their infants and low milk vitamin B-12 levels have also been seen. These findings strongly support the need for vitamin B-12 supplementation of lactating women on diets devoid of animal products. As the slide indicates, a regular source of vitamin B-12 such as fortified foods or supplements providing 2.6 mcg vit b-12 daily are indicated.
Studies of lactating women with low calcium intakes suggest that some compensation occurs via increased absorption . Calcium content of breast milk may or may not be affected by low maternal calcium intake . Due to concern with maternal bone health and possibly with milk calcium concentration, a calcium intake of 1000 mg daily or 1300 mg for adolescents is recommended in lactation .
Milk vitamin D content varies with maternal diet and sun exposure but is normally quite low. Adequate vitamin D, either from diet or sun exposure, is important during lactation to maintain maternal calcium status and prevent bone demineralization. The NAS recommends use of fortified foods and/or exposure to ultraviolet light or supplement providing 5 mcg vitamin D daily.
Slide - veg lactation
The next slide provides some information about vegetarian lactation. More infants of vegetarian women are breastfed and the duration of lactation is commonly longer. These are trends which should be supported and promoted.
The nutrient content of breast milk is affected by maternal diet. Milk from vegetarians who are well-nourished would be expected to be similar to milk from well-nourished non-vegetarians . Vegetarians have higher milk concentrations of polyunsaturated fatty acids derived from dietary vegetable fat and lower concentrations of fatty acids derived from animal fat . These differences do not appear to affect the infant's health.
One important difference between milk of vegetarian and non-vegetarian women is its contaminant concentration. Studies of vegetarians show lower levels of pesticides such as DDT, chlordane, and heptachlor and industrial biproducts such as polychlorinate d biphenyls (PCBs) . Maternal intakes of meat and dairy products have a large influence on milk levels of dieldrin and PCBs .
Our last speaker, Winston Craig, will be discussing vegetarian children. I'd like to spend a few minutes on vegetarian infants, up to age 2.
Slide - growth
What do we know about growth of vegetarian infants and children? A number of studies have shown that the growth of vegetarian infants and children is often similar to stds or non-vegs provided energy intake is adequate and intakes of nutrients such as protein, vitamin D, vitamin B-12 and zinc meet recommendations. Poor growth in children has been seen primarily in children on very restricted diets, such as macrobiotic, fruitarian, raw foods. Many vegetarian parents are quite knowledgeable about nutrition and open to suggestions to optimize their children's intakes. Our task is to reinforce the positive features of the diets they have selected and to work with families to provide acceptable alternatives where necessary.
slide - lactation (slide)
For at least the first 6 months, breast milk or infant formula is the primary food for infants. Healthy vegetarian infants generally thrive during this time. I've already discussed some considerations for the maternal diet in vegetarian lactation.
Slide - Vitamin D in Infancy
Certainly it is important for lactating women to have adequate vitamin D status to optimize maternal calcium absorption. Generally, regardless of maternal diet, milk vitamin D levels are low. Vitamin D supps are recommended for breast fed infants. After weaning, supps should continue unless a reliable vitamin D source is included or there is adequate sunlight exposure. Adequate sunlight exposure in the midwestern US is 2 hrs/wk on face only or 30 min/wk wearing only a diaper
Slide - Recommended Supplements for Vegetarian Infants
Other supplements which are recommended for infants include vitamin K at birth, vitamin D (5 micrograms with limited sun), iron (1 mg/kg/d beginning at 4-6 mos or use iron-fortified formula), and fluoride (0.25 mg/d beginning at 6 mos with low water intakes for breast-fed infants; for formula-fed depends on formula content) are recommended for all infants, vegetarian or not. Vitamin B-12 is only needed as a supplement for breast feeding infants where maternal diet is inadequate. 0.1-0.3 mcg.
slide - Introduction of Foods for Vegetarian Infants
Either breast milk or commercial formulas is entirely adequate for infants for the first 4 to 6 months. When foods are introduced, they are the same as those used for non-vegetarian infants: cereals, fruits, vegetables . Later, vegetarian sources of protein such as well-mashed cooked dried beans, tofu, eggs, yogurt, cottage cheese can be introduced. Finger foods could include such things as cereals, pasta, crackers, tofu cubes, and others.
Slide - baby food (photo)
Commercial vegetarian baby foods are available; label reading is necessary. Many parents will opt to prepare their own. Topics to cover in counseling would include food choices and food safety.
Slide - Weaning Considerations
Weaning is a time of nutritional vulnerability. Breast milk or infant formula are being replaced by solid foods. If these foods have a low caloric density, energy intake may be low. Fats should not be restricted. Avoid dilute formulas like rice or ot her cereal-based milks, nut milks as a substitute for breast milk or infant formula. Breast milk or formula should be the primary beverage for the first year; not cow's milk or soymilk.
Slide - Additional Weaning Considerations
May want to encourage some use of refined grains to reduce fiber intake or use peeled fruits and vegetables as necessary. Provide conc sources of calories.
Slide - energy and protein
The next slide provides information on the RDAs for energy and protein for infants and young children. As I have said before, achieving adequate energy intakes, as reflected by satisfactory growth, in vegetarian children may require some use of foods which are not excessive in fiber and which provide concentrated sources of calories.
As you can see, while these age groups have the highest protein needs on a per kg basis, their actual requirement is fairly low and can be easily met by a vegetarian diet. Diets which contain only plant sources of protein may need adjustments for protei n quality and digestibility. The 1989 RDA outlines the procedure for this adjustment. Depending on the protein sources, a 1-3 yr old vegan could require as much as 1.7 g of protein per kg. However, in practical terms, for the child weighing 13 kg, an increase of 0.5 g/kg would only lead to a need for 6 additional grams of protein per day.
Slide - veg baby (photo)
I have discussed good sources of various nutrients such as iron, calcium, zinc, and vitamin B-12. Certainly when recommending foods for vegetarian pregnant and lactating women, infants and toddlers, many of the same foods which are good sources of thes e nutrients should be chosen. If foods like tofu and other soy products, dried beans, a variety of grains, different fruits and vegetables are introduced early, children will often accept these foods.
We've covered a lot of information today. I'd like to point out a few resources for more information. A reading list was handed out.
Slide - resources
The next slide show some books and brochures - all by VN members. Dr Craig will mention VN's fact sheets, another excellent resource.
Slide - veg baby(photo)
I'd like to conclude with a slide of a happy vegetarian baby. Thank
you for your consideration and interest.