October 2015 Issue
Plant-Based Diets for the Whole Family
By Sharon Palmer, RDN
Vol. 17 No. 10 P. 28
A well-planned vegetarian or vegan diet can be healthful for people of all ages. Today's Dietitian offers tips on how you can help clients cover their nutritional bases.
From environmentally aware adolescents to health-focused middle-aged adults, more and more people are interested in the benefits of a plant-based diet. You may be noticing this trend in your own practice, whether you work in foodservice, a hospital, or a clinic. Today, you can confidently tell clients—both young and old—that a well-planned vegetarian diet not only can be nutritionally adequate but also can provide benefits for both health and the environment. After all, that's the position of the Academy of Nutrition and Dietetics1 (the Academy) and even the recent Dietary Guidelines Advisory Committee report.2
"From birth to becoming an older adult, our nutritional needs change. Nutrition science and well-documented studies support that well-planned and balanced vegan and vegetarian diets are appropriate for all the stages of the life cycle," says John Westerdahl, PhD, MPH, RD, CNS, chairman of the Academy's Vegetarian Nutrition Dietetic Practice Group (VNDPG) and director of the Bragg Health Institute.
Many people are attracted to plant-based diets for their health benefits. Indeed, research shows that vegetarian and vegan diet patterns are linked with lower incidences of obesity, cardiovascular disease, and hypertension. Studies show that plant-based diets tend to be rich in a number of important nutrients, including vitamins, minerals, fiber, and phytochemicals. National Health and Nutrition Examination Survey data show that vegetarian diets are higher in vitamins A, C, and E; and thiamin, riboflavin, folate, calcium, and magnesium than nonvegetarian diets.3 Another primary motivation behind a plant-based eating style is due to its lighter impact on the planet. Vegetarian eating patterns produce a lower carbon footprint.4
Though potential health benefits may be gained from a vegetarian or vegan diet, it's important to meet nutrient needs, especially for protein, omega-3 fatty acids, vitamin B12, calcium, vitamin D, iron, zinc, and iodine. Dietitians can work with vegetarian and vegan clients to ensure they receive adequate intake of these nutrients, particular to their life cycle stage.
Protein is an essential macronutrient with important functions, including maintaining muscle and bone mass, and supporting the immune system. It's possible to meet one's nutrient needs for protein with plant-based proteins, which tend to have a better protein package; the protein they provide is packaged with nutrients such as fiber, heart-healthy fats, vitamins, minerals, and phytochemicals. While animal proteins are considered high quality because they provide all nine essential amino acids in a good balance, some plant-based proteins may fall short on one or more essential amino acids.
It was once a popular notion that vegetarians needed to combine different plant proteins at one meal to create a complete protein, but that's no longer considered necessary. A healthful, balanced diet with a variety of whole plant foods should provide adequate amino acids throughout the day.1 Lysine is typically the limiting amino acid for many plant-based food sources, so it's important that vegans get good sources daily, such as tofu, tempeh, soyfoods, lentils, and seitan.
Studies show that the typical protein intake among vegans and vegetarians is adequate, although some vegan women may have marginal intake.1 Vegetarians may choose from animal sources, such as milk, cheese, cottage cheese, and eggs, in addition to vegan sources, including legumes, soyfoods, nuts, and seeds. In addition, whole grains and vegetables can provide notable levels of protein to the diet.
Protein recommendations per the Dietary Reference Intake (DRI) report include the following:
• Infants: 1.5 g/kg/day;
• 1 to 3 years: 1.1 g/kg/day;
• 4 to 13 years: 0.95 g/kg/day;
• 14 to 18 years: 0.85 g/kg/day; and
• Adults: 0.8 g/kg/body weight/day.5
Note: Vegans may require additional protein (about 10% more) to compensate for the reduced digestibility of plant-based proteins. Older adults may benefit from slightly more protein from 1 to 1.6 g/kg daily.1,6
Omega-3 Fatty Acids
Given that vegetarians and vegans don't consume fish, intake of the omega-3 fatty acids EPA and DHA—associated with heart health, brain development, and other benefits—may be low. Vegetarians may be getting small amounts in omega-3 fortified milk and eggs, but vegans don't consume these sources. However, vegetarian and vegan diet patterns typically are rich in the omega-3 fatty acid alpha-linolenic acid (ALA). ALA may be converted to EPA at levels generally less than 10%, with conversion to DHA at even lower levels. Conversion rates may improve when omega-6 fatty acid consumption is lower. Some experts recommend more ALA may be needed for vegetarians and vegans; sources include soy, flax, walnuts, and hemp.1
While there's no current recommendation for EPA and DHA, the Dietary Guidelines suggest two servings of fish per week—which provides about 250 mg per day on average.2 Marine algae supplements, rich in EPA and DHA, may be considered to supplement the diet.1
According to Jack Norris, RD, coauthor of Vegan for Life, vegans and vegetarians can have low omega-3 intakes and blood levels, and in some cases older vegans have close to no DHA in the blood. While it isn't clear if those levels are harmful, he suggests supplementing with 200 to 300 mg DHA every two to three days to provide insurance that you're getting enough. For vegetarians who want the same DHA levels as nonvegetarians, he suggests 300 mg per day.
ALA recommendations per the DRI report include the following:
• 0 to 12 months: 0.5 g/day;
• 1 to 3 years: 0.7 g/day;
• 4 to 8 years: 0.9 g/day;
• 9 to 13 years females: 1 g/day;
• 9 to 13 years males: 1.2 g/day;
• 14 years and older females: 1.1 g/day;
• 14 years and older males: 1.6 g/day;
• Pregnancy: 1.4 g/day; and
• Lactation: 1.3 g/day.5
Note: Some experts recommend more ALA may be needed for vegetarians and vegans—approximately 2 g per day.
This is likely the most important nutrient for vegetarians—especially vegans—to pay attention to. There's no unfortified plant food that provides significant levels of vitamin B12. While vegetarians may obtain some through dairy foods and eggs, their intake levels may be low, too. According to data presented at the International Congress on Vegetarian Nutrition at Loma Linda University in 2013, 30% to 86% of vegetarians and 43% to 88% of vegans are B12 deficient. Vitamin B12 has many important functions, including metabolism, red blood cell formation, and central nervous system maintenance. Deficiency may result in megaloblastic anemia, as well as central nervous system symptoms, such as memory loss and disorientation.1,7
According to the VNDPG, all vegetarians and vegans should be screened for B12 deficiency. Westerdahl says that status is best determined by measuring serum levels of homocysteine, methylmalonic acid, or holotranscobalamin II. He thinks it's a good idea for vegetarians as well as nonvegetarians to take a daily multivitamin and multimineral dietary supplement providing at least 100% DV for vitamin B12, as well as other essential vitamins and minerals as a form of nutritional insurance, though people can focus on single supplements of B12 that furnish 100% DV.
The VNDPG suggests that vegan adults should take 250 mcg/day—which is much higher than the Dietary Reference Intakes (DRI) recommends because supplements may be poorly absorbed. Vegetarians should take this dose a few times per week.7 While foods fortified with vitamin B12, such as nutritional yeasts, breakfast cereals, and plant-based milks can help, a consistent, reliable intake of this micronutrient must be part of the daily diet to meet needs.
Vitamin B12 recommendations per the DRI report include the following:
• 0 to 6 months: 0.4 mcg/day;
• 6 to 12 months: 0.5 mcg/day;
• 1 to 3 years: 0.9 mcg/day;
• 4 to 8 years: 1.2 mcg/day;
• 9 to 13 years: 1.8 mcg/day;
• 14 years and older: 2.4 mcg/day;
• Pregnancy: 2.6 mcg/day; and
• Lactation: 2.8 mcg/day.8
Important for bone health and muscle and nerve function, calcium typically is plentiful in the vegetarian diet due to the reliance on dairy foods for protein sources. However, vegans often consume less calcium. Of particular concern is risk of osteoporosis; some studies have shown lower bone mineral density among vegans.9 However, it is important to note that many other bone-protective nutrients, such as potassium, magnesium, and vitamin K, are abundant in vegan diets.1
Calcium food sources include dairy products for vegetarians, and calcium-fortified foods (eg, plant-based milks, orange juice, tofu made with calcium sulfate), leafy greens, broccoli, butternut squash, beans, almonds, and oranges for vegans and vegetarians. Calcium may be poorly absorbed from spinach and Swiss chard due to their high oxalate content. Supplements may be considered to help clients meet needs. Westerdahl recommends supplements containing calcium citrate malate as a preferable form due to its better bioavailability.
Calcium recommendations per the DRI report include the following:
• 1 to 3 years: 700 mg/day;
• 4 to 8 years: 1,000 mg/day;
• 9 to 18 years: 1,300 mg/day;
• 19 to 70 years males: 1,000 mg/day;
• 19 to 50 years females: 1,000 mg/day;
• 51 years and older females: 1,200 mg/day;
• 70 years and older males: 1,200 mg/day; and
• Pregnancy and lactation: 14 to 18 years: 1,300 mg/day; 19 to 50 years 1,000 mg/day.8
Vitamin D has been highlighted for its role in health protection and in promoting bone health, immune health, and nervous system and muscle function. The EPIC (European Prospective Investigation into Cancer and Nutrition)-Oxford study found a stepwise change in vitamin D levels, from meat eaters, fish eaters, vegetarians, and vegans—with the lowest levels in vegans.10 Vegetarians can get vitamin D from fortified dairy products and egg yolks, but vegans must rely on mushrooms exposed to light; fortified products such as orange juice, plant-based milks, and cereals; sunlight exposure; and supplements.
Vitamin D recommendations per the DRI report include the following:
• 0 to 12 months: 10 mcg/day;
• 1 to 70 years: 15 mcg/day; and
• 70 years and older: 20 mcg/day.8
Found in the hemoglobin of red blood cells, iron is necessary for oxygen transport throughout the body, in addition to other important functions, including immunity and DNA synthesis. The body can store iron and increase absorption when stores drop. Heme iron (from animal sources) is better absorbed than nonheme iron (from plant sources). Interestingly, some research shows that high heme intake may be linked to increased risk of chronic disease.11
Although more research is needed, studies suggest that vegetarians and vegans tend to have adequate iron stores, though children and women may be at risk of deficiency. Sources of iron for both vegetarians and vegans include grains, legumes, leafy greens, tofu, and enriched cereals. Due to reduced bioavailability of iron, it's recommended that vegetarians and vegans consume 1.8 times the recommended dietary allowance (RDA) for iron. Consuming beans, grains, and seeds that have been soaked, sprouted, fermented, and cooked can increase iron absorption. In addition, the presence of vitamin C with iron sources can increase its absorption level, and cooking foods in an iron skillet can increase iron intake as well. Phytates, calcium, and polyphenols in tea, coffee, and cocoa can inhibit iron absorption.1,11
Iron recommendations per the DRI report include the following:
• 0 to 6 months: 0.27 mg/day;
• 6 to 12 months: 11 mg/day;
• 1 to 3 years: 7 mg/day;
• 4 to 8 years: 10 mg/day;
• 9 to 13 years: 8 mg/day;
• 14 to 18 years females: 15 mg/day;
• 14 to 18 years males: 11 mg/day;
• 19 years and older males: 8 mg/day;
• 19 to 50 years females: 18 mg/day;
• 51 years and older females: 8 mg/day;
• Pregnancy: 27 mg/day; and
• Lactation: 14 to 18 years: 10 mg/day; 19 to 50 years: 9 mg/day.8
Note: Vegetarians and vegans should consume 1.8 times the RDA for iron, due to its reduced bioavailability.11
This important mineral plays roles in both the immune system and structure of DNA. Studies show that some vegetarians and vegans have slightly lower zinc levels, though more research is needed among free-living adults in developed countries. Zinc may be found in dairy products (for vegetarians) and nuts, whole grains, soy, and beans (for vegans). However, due to the presence of inhibitors in plant sources, bioavailability may be diminished. It's recommended that vegetarians and vegans consume 50% more than the current DRI recommends for zinc.1,12
Zinc recommendations per the DRI report include the following:
• 0 to 6 months: 2 mg/day;
• 6 to 12 months: 3 mg/day;
• 1 to 3 years: 3 mg/day;
• 4 to 8 years: 5 mg/day;
• 9 to 13 years: 8 mg/day;
• 14 to 18 years: females 9 mg/day;
• 14 years and older: males 11 mg/day;
• 19 years and older females: 8 mg/day;
• Pregnancy: 14 to 18 years: 12 mg/day; 19 to 50 years: 11 mg/day; and
• Lactation: 14 to 18 years: 13 mg/day; 19 to 50 years: 12 mg/day.8
Iodine is used in the production of thyroid hormones, which control metabolism and other important body functions. Little research has been done on the status of iodine among vegetarians and vegans, although a recent study of Boston-area vegetarians and vegans found that they were at risk of low iodine intake.13 Iodine may be found in dairy products, for vegetarians, as well as iodized salt, sea vegetables, fruits, and vegetables. Sea vegetables contain varying levels of iodine—sometimes extremely high levels. And fruits and vegetables contain varying levels based on the soil and fertilizer with which they were grown. Some plant foods, such as cruciferous vegetables, soybeans, and sweet potatoes contain naturally occurring goitrogens, which may counteract high iodine intake. Supplemental iodine may be considered for people at risk of low iodine status.1
Iodine recommendations per the DRI report include the following:
• 1 to 8 years: 90 mcg/day;
• 9 to 13 years: 120 mcg/day;
• 14 years and older: 150 mcg/day;
• Pregnancy: 220 mcg/day; and
• Lactation: 290 mcg/day.8
From birth to 6 months of age, the diets of many infants of vegan and vegetarian parents are identical to those of nonvegetarian parents. The perfect food for a young infant is breast milk, and supplementary foods shouldn't be introduced until 6 months of age. Well-nourished vegetarian women's breast milk is similar to that of nonvegetarian women.1 If mothers can't breast-feed, babies may be fed formula (soy-based or cow's milk-based for vegetarians). Many soy infant formulas are appropriate for vegan diets, though some contain animal fats so it's important to read ingredient lists. Soy, rice, or other plant-based milks and homemade formulas shouldn't be used to replace breast milk or commercial formula during the first year of life because they may not contain the proper ratio of protein, fat, carbohydrates, vitamins, and minerals needed.14
Some nutrients are of concern for all infants, whether they're vegetarian or not. All should receive 400 IU/day of supplemental vitamin D within the first days after birth. Iron is recommended at four months for all breast-fed infants, and some may require supplemental fluoride after six months if fluorinated water intake is low.14
For infants aged 6 months to 2 years, breast milk continues to be an important source of nutrients; vegetarian and vegan infants should rely on it for at least one year as they transition to solids. After weaning, vegan infants should include fortified soymilk (or milk for vegetarians) containing calcium and vitamins B12 and D. Low-fat or nonfat soymilks shouldn't be used before age 2; rice and other plant-based milks aren't recommended as a primary beverage for infants and toddlers.14
"The typical recommendation for infants is to start feeding them iron-fortified cereal around 6 months of age, along with plenty of protein and fat-containing foods, and vitamin B12—there should be little difference between vegan children and non-vegan children," says Reed Mangels, PhD, RD, LDN, a nutrition advisor for the Vegetarian Resource Group.
Ground oats, barley, corn, and other grains cooked until very soft can be introduced one at a time, but iron supplements should be continued. Next, mashed or pureed vegetables and fruits and fruit juice can be offered to infants. Grain foods, such as cooked pasta or rice, soft breads, dry cereals, and crackers can be introduced as the baby shows readiness. At 7 to 8 months of age, protein sources, such as well-mashed cooked beans, mashed tofu, soy yogurt, and smooth nut/seed butters (after one year, later if prone to allergies) may be added. Commercially prepared baby foods are appropriate for vegetarian or vegan infants, and home prepared baby foods—washed, cooked, and mashed—may be included as the baby progresses. The overall focus for children aged 1 to 3 should be nutrient-dense foods and adequate intake of calories and fat to meet energy needs and growth, as well as protein, calcium, vitamins B12 and D, iron, and zinc through age-appropriate foods and supplements.14 For a feeding schedule for vegan babies aged 6 to 12 months and 1 to 3 years, visit www.vrg.org/nutshell/kids.php.
The nutrition goal for both vegetarian and vegan children is to eat a nutrient-rich diet that can support appropriate growth and development. There are many benefits of a vegetarian diet during childhood, including lifelong healthful eating habits, lower body weight, lower intakes of cholesterol and fat, and higher intakes of fruits, vegetables, and fiber.1,15,16
It's important to meet the energy needs of children during this period of growth. Vegetarian and vegan diets are typically high in fiber, which can prompt children to become full easily. Thus, you can include some refined foods, small, frequent feedings, and adequate fat to promote appropriate growth. Nutrients of concern include vitamin B12 and D, calcium, protein, iron, and zinc, which may be obtained through age-appropriate foods and supplements.15 For a feeding schedule for children aged 4 to 13, visit www.vrg.org/nutshell/kids.php.
Studies show that vegetarian teens have similar growth rates as omnivores and that they consume more fruits, vegetables, fiber, iron, folate, and vitamins A and C, and fewer sweets, fast foods, and salty snacks than do nonvegetarians. Nutrition concerns for this age group include obtaining adequate calories and protein for growth and development, iron (especially for girls), zinc (important for growth and sexual maturation), calcium, and vitamins B12 and D through foods and supplements.17 In addition, the potential for eating disorders as a possible motivation for a vegetarian or vegan diet should be examined.
"Adolescents can refuse to eat various foods, and there can be a tendency toward getting anemia in some cases in girls. But they just need to follow recommendations of eating foods high in iron and vitamin C, and should be fine," Mangels says.
During adulthood, the goal for vegetarians and vegans is to eat a nutrient-rich diet that promotes a healthful weight and prevents chronic disease. Maintaining proper bone health, especially for women, is a priority. According to Mangels, adequate calcium and vitamin D are important, but she warns against the persistent myth that vegans don't have to worry about calcium because their diets don't contain animal protein, or because their diets are lower in protein. "Recent research suggests that adequate protein is important for bone health and that, even though diets high in animal protein can cause increased calcium losses in urine, they also promote calcium absorption, so the overall effect of higher protein intakes on bone status is minor. Vegans and other vegetarians should meet the RDA for both calcium and protein. Other important nutrients for bone health include potassium, vitamin B12, vitamin C, magnesium, and vitamin K," Mangels says.
Overall, Mangels recommends eating a variety of foods, ensuring adequate vitamin B12 from fortified foods and/or supplements, and using food and/or supplements to ensure adequate calcium and vitamin D intake.
According to Mangels, the nutrients of concern for pregnancy are the same as for all adults. "I'd also consider iodine since iodine intakes in the United States are lower than in the past. I'd keep standard recommendations for supplemental folic acid in mind for pregnant women or women capable of becoming pregnant," she adds.
Vegetarian women successfully can breast-feed, and studies show their milk is lower in environmental toxins than women who eat meat. During lactation, women should ensure a balanced diet with enough vitamin B12, as well as other nutrients per the DRI.18
Many older adults are attracted to vegetarian diet patterns for disease protection or even reversal. However, there are a few nutrients of concern among this group. "All older adults, whether or not they're vegetarian, have higher needs for calcium, vitamin D, and vitamin B6. Many experts believe that older adults also need more protein," says Virginia Messina, MPH, RD, coauthor of Never Too Late to Go Vegan and Vegan for Life. "One advantage for older women is that iron needs drop after menopause. And vegetarians and vegans also have a particular advantage regarding vitamin B12. Many older adults don't absorb vitamin B12 very well from animal foods and therefore require more easily absorbed supplements. Since vegans and many vegetarians already take B12 supplements, they already have this important habit established."
Messina recommends calcium-fortified foods, since it can be challenging to meet the higher calcium recommendations of people over age 50. Some older vegetarians may benefit from small calcium supplements—just enough to make sure they meet recommendations if dietary calcium falls short.
"Many older vegetarians and nonvegetarians also need vitamin D supplements. And although the research on this issue is conflicting, older vegetarians may want to consider a supplement of the long chain omega-3 fats DHA and EPA from microalgae," Messina says.
Mangels adds that all older adults should ensure adequate protein and zinc intake, though it may be particularly true for vegans, whose diets tend to include lower levels of these nutrients.
Putting It Into Practice
So, how can dietitians provide the best nutrition advice to their vegetarian and vegan clients? "It's important to make sure patients are eating a well-balanced variety of foods, including whole grains, vegetables, fruits, legumes, nuts, and seeds to ensure they meet their nutrient needs. If they're unnecessarily restricting their diet, there's a greater likelihood there could be a shortfall in certain nutrients," Westerdahl says.
A few things to watch for, according to Westerdahl, is a diet filled with heavily processed plant foods, which can result in falling short on nutrients. Norris suggests other potential concerns, such as higher iron needs for female athletes, and watching for symptoms such as fatigue or loss of libido. Mangels suggests checking that clients (especially children) don't overly restrict fats, or don't rely too heavily on one food.
Blood tests may be recommended on an individual basis, depending on dietary choices and health status, according to Mangels. Norris recommends a vitamin B12 (via methylmalonic acid combined with serum B12), vitamin D, and iron deficiency panel as tests that may reveal what's wrong if patients present with symptoms.
The following factors may be helpful in making an assessment of your client, according to Mangels (adapted from the Academy's Pediatric Manual of Clinical Dietetics):
• type and duration of vegetarian diet;
• specific foods eaten and foods avoided;
• food allergies and intolerances;
• dietary supplements and herbs;
• nutrient intake assessment based on dietary intake;
• health issues requiring dietary modification;
• activity level;
• relevant lab tests; and
• weight history/growth charts.
Dietitians are the perfect experts to provide nutrition guidance to vegetarian and vegan clients. Staying informed and looking for reliable resources are key.
— Sharon Palmer, RDN, is author of Plant-Powered for Life, editor of Environmental Nutrition, nutrition editor of Today's Dietitian, and nutrition advisor for Oldways Vegetarian Network.
• The Vegetarian Nutrition Dietetic Practice Group: www.vndpg.org
• The Vegetarian Resource Group: www.vrg.org
• The Dietitian's Guide to Vegetarian Diets, 3rd ed, by Reed Mangels, Virginia Messina, and Mark Messina
• Oldways Vegetarian and Vegan Diet Pyramid: http://oldwayspt.org/programs/oldways-vegetarian-network/vegetarian-vegan-diet-pyramid
1. American Dietetic Association. Position of the American Dietetic Association: vegetarian diets. http://www.vrg.org/nutrition/2009_ADA_position_paper.pdf. Published July 2009. Accessed August 4, 2015.
2. US Department of Health and Human Services. Scientific report of the 2015 Dietary Guidelines Advisory Committee. http://health.gov/dietaryguidelines/2015-scientific-report/. Published February 2015. Accessed August 4, 2015.
3. Farmer B, Larson BT, Fulgoni VL 3rd, Rainville AJ, Liepa GU. A vegetarian dietary pattern as a nutrient-dense approach to weight management: an analysis of the national health and nutrition examination survey 1999-2004. J Am Diet Assoc. 2011;111(6):819-827.
4. Watson E. Environmental footprint of vegan and vegetarian diets 30% lower than non-vegetarian diets, says researchers: 'We have to drastically cut consumption of meat and dairy.' Food Navigator USA website. http://www.foodnavigator-usa.com/R-D/Environmental-footprint-of-vegan-and-vegetarian-diets-30-lower-than-non-vegetarian-diets-say-researchers-We-have-to-drastically-cut-consumption-of-meat-and-dairy. Updated March 1, 2013. Accessed August 4, 2015.
5. United States Department of Agriculture. Dietary reference intakes: macronutrients. http://www.nal.usda.gov/fnic/DRI/DRI_Tables/macronutrients.pdf. Accessed August 5, 2015.
6. Bernstein M, Munoz N; Academy of Nutrition and Dietetics. Position of the Academy of Nutrition and Dietetics: Food and nutrition for older adults: promoting health and wellness. J Acad Nutr Diet. 2012;112(8):1255-1277.
7. Pawlak R. RD resources for professionals: vitamin B12 in vegetarian diets. http://vndpg.org/docs/rd-resources/B12-RD.pdf. Accessed August 4, 2015.
8. Institute of Medicine. Dietary reference intakes (DRIs): recommended dietary allowances and adequate intakes, vitamins and elements. National Academies of Sciences, Engineering, and Medicine website. http://iom.nationalacademies.org/~/media/Files/Activity%20Files/Nutrition/DRIs/
New%20Material/2_%20RDA%20and%20AI%20Values_Vitamin%20and%20Elements.pdf. Accessed August 5, 2015.
9. Ho-Pham LT, Nguyen ND, Nguyen TV. Effect of vegetarian diets on bone mineral density: a Bayesian meta-analysis. Am J Clin Nutr. 2009;90(4):943-950.
10. Crowe FL, Steur M, Allen NE, Appleby PN, Travis RC, Key TJ. Plasma concentrations of 25-hydroxyvitamin D in meat eaters, fish eaters, vegetarians and vegans: results from the EPIC-Oxford study. Public Health Nutr. 2011;14(2):340-346.
11. Norris J. RD resources for professionals: iron in vegetarian diets. http://vndpg.org/docs/rd-resources/Iron-RD.pdf. Accessed August 6, 2015.
12. Norris J. RD resources for professionals: zinc in vegetarian diets. http://vndpg.org/docs/rd-resources/Zinc-RD.pdf. Accessed August 6, 2015.
13. Leung AM, Lamar A, He X, Braverman LE, Pearce EN. Iodine status and thyroid function of Boston-area vegetarians and vegans. J Clin Endocrinol Metab. 2011;96(8):E1303-E1307.
14. Mangels R. RD resources for consumers: vegetarian infants. http://vegetariannutrition.net/docs/Vegetarian-Infants.pdf. Accessed August 6, 2015.
15. Creighton C. RD resources for consumers: vegetarian nutrition for school-aged children. http://vegetariannutrition.net/docs/School-Aged-Children-Vegetarian-Nutrition.pdf. Accessed August 6, 2015.
16. Sabaté J, Wien M. Vegetarian diets and childhood obesity prevention. Am J Clin Nutr. 2010;91(5):1525S-1529S.
17. Bousleiman C. RD resources for consumers: vegetarian teens. http://vegetariannutrition.net/docs/Teens-Vegetarian-Nutrition.pdf. Accessed August 7, 2015.
18. Creighton C. RD resources for consumers: vegetarian diets during lactation. http://vegetariannutrition.net/docs/Lactation-Vegetarian-Nutrition.pdf. Accessed August 6, 2015.