Nutritional Considerations for the Vegetarian and Vegan Dancer.
A recent study that assessed the energy intake and expenditure of pre-professional contemporary dancers by Brown et al. (9) determined that seven of the 25 dancers in their study self-reported being either vegan, vegetarian, or actively avoiding red meat. In the UK national survey into dancers' health, Brinson and Dick (10) reported that between 30% to 40% of the dancers in their cohort were vegetarian. Similarly, in an international study that assessed the prevalence of dietary supplement consumption among dancers, 33% of dancers acknowledged being vegetarian. (11)
Frusztajer et al. (12) assessed the effects of nutrition on the incidence of stress fractures among classical ballet dancers. Vegetarianism was measured to determine the degree of food choices in a cohort of dancers. Of the 50 dancers who were examined, 60% self-reported as vegetarian, and in all groups low caloric and restrictive dietary tendencies were noted. Further, nutrition data revealed that dancers with stress fractures were more likely to consume diets with less than 85% of the recommended daily allowance, to avoid foods with high fat content, and to consume more low-calorie-dense foods. While correlation between vegetarianism and injury prevalence was not the aim of this study, restrictive dietary patterns and eating disorder pathologies were more salient in the stress fracture group.
Consequently, some vegetarian diets are not without provisos. Vegan diets require more conscientious planning, and raw-food diets may even be detrimental to long-term health. In light of the above mentioned considerations, a key purpose of this review is to characterize different types of vegetarian diets. Secondly, potential macronutrient and micronutrient deficiencies that can occur in poorly planned and managed vegetarian diets will be highlighted via information garnered from research in sport and performance nutrition. Finally, evidence-based recommendations will be provided. This topic-content review focuses on the potential implications dietary choice can have on dance performance, and does not provide a meta-analytic review of vegetarianism in dancers.
All vegetarian diets are plant-based. Thus, the key foods ingested are fruits, vegetables, edible sea vegetables, grains, legumes, pulses, nuts, and seeds. As shown in Figure 1, vegetarian diets are classified into two main categories, vegetarian and vegan, with each category further subdivided by the inclusion or exclusion of processed or naturally occurring products. To avoid confusion, terms like "flexitarian" or "pescitarian" are avoided, as these diet types contain animal flesh products and thus fall under the term "omnivore."
The lacto- and ovo-vegetarian diets are the most common across populations. (13) The inclusion of dairy (lacto), eggs (ovo), or both (lacto-ovo) in these diet types provides good sources of protein, quality fats, vitamin D (cholecalciferol), calcium, and vitamin [B.sub.12] (cyanocobalamin). Vegans follow a diet that excludes all by-products derived naturally (milk, eggs) or processed (cheese, yogurt) from animals. Both vegan and vegetarian diets offer a host of quality macro and micronutrient profiles required for good health. Fruitarians and crudivores (raw food eaters) form a subcategory of vegans, characterized by the consumption of between 50% to 95% in weight of total food intake as raw food. (14,15) Raw food diets also garner positive health outcomes, such as favorable serum LDL cholesterol, triglycerides, (16) plasma b-carotene, and plasma lycopene concentrations. (14) However, a raw food diet, particularly for female athletes and aesthetic athletes such as dancers, can be problematic. In female individuals, a lacto-ovo vegetarian diet need not accompany menstrual disturbances or a reduction in body mass index (BMI). (6,17,18) However, a diet of predominately raw foods is associated with extreme weight loss, leading to suboptimal or underweight and amenorrheic individuals. (19) Ultimately, this predisposes female dancers with hypocaloric diets of all types to menstrual cycle disorders, severely low BMI, and consequently reduced muscle and skeletal strength sufficient to meet the demands of dancing. (20) There is insufficient evidence currently to recommend a raw diet as optimal for long-term sustained dance performance.
Consistent, high quality dance performance depends on applicable nutrition that, in addition to basal metabolic needs, also meets the physical demands of class, rehearsal, and performance. Ballet, urban, or contemporary styles all have different energy demands; thus there is no "one size fits all" diet appropriate for every dancer. For all dancers, however, and particularly for vegetarians, the macronutrient composition of diet must be sufficient in energy, i.e., calories. The International Association for Dance Medicine & Science (IADMS) offers general recommendations regarding macronutrient distribution of dancers' diet: 55% to 60%, 20% to 30%, 12% to 15% of carbohydrates (CHO), fats, and protein, respectively. (21) Including all three macronutrients in a vegetarian diet provides a host of benefits: favorable gastrointestinal microbiota, (2) high polyunsaturated fats, which contribute to stable blood pressure, (22) as well as a complete spectrum of essential amino acids that support bone health and muscle repair. (23) More comprehensive analyses of the macronutrients and caloric needs are covered elsewhere. (21,24) The section below highlights macronutrient research relevant to vegetarian diets.
Vegetarian dietary patterns across all categories are abundant in a range of CHO sources. In an examination of dietary data from 63 research studies, Mangels, Messina, and Messina (25) reported the CHO intake ranges of vegans from 50% to 65% and lactoovo vegetarians from 50% to 55% when compared to non-vegetarians in the general population who have an intake of 50% or less. In epidemiologic studies, a key factor in the health benefits claimed for plant-based diets are partly due to a diverse range of micronutrients, phytochemicals, and dietary fiber present in CHO rich plant-based food sources. (13,26) Due to the intermittent intensity demands of many dance genres, (27) a dancer will use energy from a variety of stored carbohydrates (glucose) and fat (fatty acids) sources during a class, rehearsal, or performance. However, at low to moderate intensity, quality (i.e., more whole, less refined) CHOs provide more energy during time worked than fats, and thus remain the preferred macronutrient of choice for dancers, due in part to their discernible effect on blood glucose levels. (28)
Fats are also essential as a macronutrient. Quality fats are energy dense and thus provide the body with an additional energy source during low or no intensity moments. Lacto-ovo vegetarian diets provide adequate sources of good fats. A repeated caveat is warranted for vegan or raw food choices, however. Vegan diets may contain good sources of polyunsaturated fats found in some nuts and seeds and leafy greens. Omega-3 and and omega-6 ([omega]-6) are essential fatty acids and cannot be made by the human body and thus must be included in the diet. (29) Omega-3s are particularly important for cardiovascular, brain, and eye health (,30,31) and may enhance aerobic metabolism. (6,21) However, vegan diets contain little if any bioavailable essential [omega]-3 fatty acids and thus require more careful planning. Research consistently reports that a balanced consumption of essential [omega]-3 fatty acids, docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA) is deficient in poorly planned vegetarian and vegan diets. (6,30,31)
Vegan diets are typically rich in [omega]-6 fatty acids, which are abundant in many plant sources. Docosahexaenoic acid and EPA originate from marine, animal, and plant life (algae), but are primarily obtained from the consumption of fish, animal organ meats, some eggs, and in insignificant quantities dairy--all foods that vegans do not ingest. Often, popular media sources suggest that vegans need only ingest sufficient quantities of flax seeds, chia seeds, hemp seeds, some walnut varieties, and dark leafy greens to meet their essential fatty acid needs. These plant-based foods contain alpha-linolenic acid (ALA), a [omega]-3 fatty acid that can be purportedly elongated in the body to produce EPA and DHA. (32) Unfortunately, this conversion is multifactorial and thus less reliable across individuals in its potential bioavailability. Genetics, for example, may contribute to an individual's ability to metabolically convert ALA to DHA and EPA. (33) Fortunately, ALA is easily converted to EPA, while DHA, via a retrocon-version process, can convert to EPA. (34) Thus an algae-based DHA dietary supplement plus continuous dietary intake of ALA sources has been recommended to supply adequate levels of [omega]-3s, particularly in vegan diets. (35)
Contrary to popular claims, plant-based protein is not inferior to animal protein; rather, the variety and quality of the amino acid profile plays a larger role in total endogenous protein up-take. (36,37) In contrast, while vegetarians ingest less protein than omnivores, the amounts are well within the recommended daily range. (5,38) For dancers, the additional need for intake of quality protein relates to its role in muscle repair due to injury. (39) However, dancers need not increase dietary intake above the recommended range for similar-type athletes of 1.2 to 1.6 g per kilogram of body weight, depending on level of activity and gender. (21,40) Muscle inactivity limits, while muscle activity increases, the amount of required protein.
Historically, plant proteins have been viewed as less digestible than animal proteins due largely to the procedure of amino acid measurements regarding nitrogen balance. (41) Consequently, digestibility of protein is often confused with the metabolism and the eventual net result of endogenous amino acids. New methodologies have redressed the ostensible discrepancy between different types of protein, and currently both animal and plant proteins are considered adequate. (8,42) Thus, a sensible adjustment in a lacto-ovo diet is between 10% to 15% (25) daily intake of protein, a range well within the current recommendations for dancers. (21) Due to the potential of lower digestibility of plant-only protein sources, the vegan recommendation offers an increased protein intake of between 15% to 20% for age 6 years and older, in comparison with non-vegetarians. (43) This also presents an increase in the range recommended for omnivore dancers, (21) which can be altered when recommended caloric intake is maintained. Individuals who adopt a raw food diet lean toward a low or severely restrictive caloric intake (16) and substandard protein intake. (14,44) This can lead to deleterious effects skewed toward amenorrhoeic (19) and bone health challenges that accompany the female athlete triad and the relative energy deficiency in sport (RED-S). (6,45,46) There are scant anecdotal and clinical data that confirm or reject the benefit of a raw food diet for physical performance enhancement. Consequently, given our current knowledge of the challenges dancers face regarding amenorrhea and resulting reduction in BMI, (47,48) a long-term, severely caloric restrictive raw food diet in dancers is ill-advised and should not be undertaken without regular monitoring by a clinical dietitian for early detection and treatment of metabolic deficiencies.
Vitamins and minerals consist of elements needed in small or micro amounts for optimal health. Table 1 provides an overview of select micronutrients that require due consideration when planning a vegetarian diet, (5,25) and a few of these nutrients are highlighted in some detail in the following section.
With regard to Vitamin [B.sub.12], vegans must plan carefully to include reliable sources of this vitamin in their diet. Vegans have lower serum Vitamin [B.sub.12] levels than do lacto-ovo vegetarians. (23,38) The depreciable effects of [B.sub.12] deficiency can present within 2 years of adopting a vegan diet, and inadequate intake over time may lead to macrocytic anaemia. (49,50) Macrocytic anaemia is associated with reduced oxygen transport, which ultimately results in impaired aerobic performance. In vegetarian and strict vegans it may be disguised due to high folate intakes seen in vegetarians who consume generous amounts of fruits, vegetables, legumes, and whole or enriched grains. A specious claim in some vegetarian communities is that fermented soy-based foods, sea vegetables, and fermented non-soy foods, for example miso and shitake mushrooms, contain adequate amounts of naturally occurring Vitamin [B.sub.12]. Research, however, has shown no conclusive relationship between serum [B.sub.12] values and the intake of these food types, (50) and if it is present, it is in negligible quantities. (51) Thus all vegetarians may benefit from the inclusion of fortified foods like nutritional yeast to maintain [B.sub.12] levels. Consulting the labelling on vegan and vegetarian foods for adequate planning and preparation in the diet can provide more assurance [B.sub.12] is consistently a part of daily intake. The inclusion of synthetic [B.sub.12] as a dietary supplement has also been recommended for vegan individuals, including athletes. (7,23,35)
Iron is an essential nutrient. It is required for the formation of hemoglobin and myoglobin, protein metabolism, and for proper function of the mitochondria. In addition, iron functions as a co-factor for a number of enzymatic processes and is thus important systemically for metabolic reactions in the body. Iron presents in two dietary forms; heme iron and non-heme iron. Heme iron, found in meats, fish, and poultry, is considered more bioavailable and easily absorbed than non-heme iron, which is found in grains, vegetables, and fruits. Dairy products contain only negligible amounts of iron and are not considered a viable dietary source.
General population studies that compared iron intake and status of vegetarians with non-vegetarians reveal statistically lower, but within range, serum ferritin concentrations. (38) However, both vegetarian and omnivore athletes may have difficulty in meeting the dietary requirements for iron. (23,40) The quantity of iron ingested reveals little of how iron is absorbed, which is of particular importance to vegetarians. Favorable adaptations regarding increased iron absorption and decreased iron loss appear possible in long-term lacto-ovo vegetarians. (52) Limited research has demonstrated iron deficiency among dancers. Beck et al. (53) conducted a cross-sectional study investigating the nutritional status of 47 female adolescent ballet dancers. Via hematological analysis, their results revealed 28% (13) of their participants had suboptimal iron status, four had iron deficiency, and one was considered severely iron deficient. In agreement, Lee et al., (54) while using similar biochemical methodology in comparing ballet students to professionals, demonstrated positive correlations between low iron and anemia-related factors. In both studies, neither dietary quantity of iron nor type of diet was offered as a factor in the results reported. Because iron plays an essential role in energy metabolism and helps transport oxygen throughout the body, it is essential for dancers to have adequate iron stores. (39)
An additional challenge with iron bioavailability is the presence of phytates. Phytates are naturally occurring anti-nutritional factors that can negate the bioavailability and digestibility of some proteins and many minerals, such as iron, zinc, (55) and calcium. (56) Polyphenols in tea, coffee, red wines, and some leafy greens may also inhibit micronutrient absorption. Figure 2 provides an overview of plant foods rich in iron that vegans can include in their diet. To diminish phytates levels, germination of grains and pulses, fermentation of soy products, as well as the addition of ascorbic acids naturally found in many fruits increase the bioavailability and absorption of zinc and iron. (41)
Vitamin D is a key macronutrient involved in bone health. It is one of the few known nutrients dependent on sunlight for synthesis in the human body. Vitamin D is also a factor in the regulation of many skeletal and cellular processes of importance in physical performance. Approximately 85% to 90% of vitamin D is formed in the skin following sunlight exposure; the remaining amount is obtained from the diet. Vitamin D exerts considerable influence on the metabolism of the micronutrients calcium and phosphorus, as well as key bodily organs: intestine, bone, and kidney. The active metabolite 1,25(OH) 2 vitamin D3 (calcitriol) facilitates active calcium absorption in the intestine.
Vitamin D deficiency does exist among vegetarian populations. In a comparative study, Larsson and Johansson (38) assessed the dietary intake and nutritional status of young Swedes, 30 vegans and 30 omnivores. Females in particular had dietary intakes lower than the average recommendation for vitamin D. An additional cause pointed toward a lack of endogenous production of vitamin D via skin exposed to ultraviolet B (UVB) light, which is present in limited quantities between November and February in Northern Sweden where the study took place. Similar results have been seen in Danish (57) and Finnish (58) vegans.
Copious research in both adolescent and adult dance populations reveals similar challenges with regard to Vitamin D levels. Wolman et al. (59) studied a group of 19 UK-based elite classical ballet dancers (6 males, 13 females) over a 6-month period for 25-hydroxyvitamin D. During the winter, all 19 dancers were either insufficient (N = 14) or deficient (N = 5) in serum 25(OH)D, with a group mean of 38.7 pg/ml in the winter. During the summer months 14 dancers were insufficient and 2 were deficient, with a group mean of 26.3 pg/ml. In a pilot study of 18 male dancers between the age of 10 to 19 conducted in Australia, Ducher et al. (60) found similar results, with a group mean of 50.5 nmol/L. While studies with such small cohorts are not generalizable, they do provide a glimpse into the challenges preprofessional and professional dancers may face. Notable in both studies are the similar findings across genders and, importantly, in different geographic locations. A probable reason for vitamin D deficiency in young dancers is insufficient sun exposure. (61) When studying at pre-professional academies, most dancers spend considerable time in the dance studio, upward of 5 to 6 hours a day, and so receive little exposure to sunlight, particularly in the northern latitudes during winter months.
Together with the studies on vegetarians and vegans from Scandinavian countries, it is reasonable to presume that vegan dancers with poorly planned diets and limited sun exposure also have low levels of this nutrient. Vegans should be advised to review carefully food labelling to include foods fortified with vitamin D2, and if extremely low levels are suspected to seek the advice of a clinical dietitian to assess serum vitamin D levels and discuss potential supplementation. Table 2 provides an overview of vitamin D foods. (62)
With the inclusion of dairy products, calcium intakes of lacto-vegetarians are comparable to, or higher than, those of omnivores. (25) Consequently, the challenges that may accompany poorly planned vegan type diets with regard to calcium are highlighted. In the Oxford cohort of the European Prospective Investigation into Cancer and Nutrition (EPIC-Oxford) study, Appleby et al. (63) compared fracture rates in four dietary groups; carnivores, fish eaters, vegetarians, and vegans. The more than 1,100 vegans in this cohort had a 30% greater risk of skeletal fracture than the other groups, possibly due to a below average intake and bioavailability of calcium. In a raw food diet, both low calcium and low protein intake have been reported. (44)
Vegans require calcium fortified foods that in combination and variety may help meet their daily calcium needs. (56) Some dark green vegetables, while rich in calcium, can also be high in oxalates and phytates, which can inhibit the absorption of calcium. (64) However, ensuring adequate sources of calcium in vegan diets usually decreases the solubility of oxalates. (36) Table 3 provides an overview of potential plant-based calcium foods. (62,65)
Sufficient Energy Intake with a Plant-Based Diet
To reiterate a key theme mentioned at the beginning of this article, appropriately planned diets require more elucidation. Inherent in the idea behind appropriately planned diets is balance. While a balanced diet can vary across countries and culinary cultures, the key to all is a variety of food types that contain all the necessary nutrients in adequate amounts to enhance the overall health of the individual. Well balanced or appropriately planned vegetarian diets require a good understanding of where to find key nutrients in food sources, as has been stated above. Vegans' diets, in particular, require extensive knowledge of how to maximize energy intake, meal preparation, and absorption of nutrients. Those who adopt a haphazard approach to planning may not enjoy the health benefits of a vegan diet, and can cause harm in the long term. A spurious presumption is that energy demands (in the form of calories) can be lower for those adopting a plant-based diet, and therefore individuals can eat less. This claim is inaccurate and does not represent healthy dietary advice. Both male and female vegans report energy intakes below recommendations, due possibly to reduced food intake. (66) Dietitians and nutritionist who counsel dancers regularly report that vegans often fail to meet their energy demands due to the high nutrient density and high fiber content of a vegan diet. Moreover, while not significantly documented via research, numerous clinical dietitians report poor skeletal health in many of their vegetarian patients. Thus, when unbalanced (excessively high fiber), inappropriately planned (timing of certain foods to maximize nutrient absorption), and poorly designed (excessive intake single foods or dietary supplements), a vegan diet can limit the ability to consume the requisite number of calories needed to maintain a positive energy balance.
Individuals who adopt raw food diets tend toward a severely restrictive caloric intake (16) and inferior protein intake. Over time this can lead to deleterious effects skewed toward amenorrheic and bone health challenges that accompany the female athlete triad and the Relative Energy Deficiency in Sport (RED-S). There are scant observational and clinical data that confirm or reject the benefit of a raw food diet for physical or athletic performance enhancement. Consequently, given our current knowledge of the challenges dancers face with regard to amenorrhea, bone health, and reduction in BMI, a long-term, severely caloric restrictive raw food diet in dancers is ill advised and should not be undertaken without regular monitoring by a clinical dietitian for early detection and treatment of metabolic deficiencies.
To date, well-controlled long-term studies assessing the effects of vegetarian or vegan diets on dancers' performance have not been conducted. Thus, a conclusive position that supports or refutes these types of diets cannot be presented. Nonetheless, some tentative observations can be made:
1. There is sufficient evidence from athletic populations to infer that a well-planned and managed vegetarian diet that includes a variety of plant-based foods can confer the healthful benefits required to meet the energy demands of the profession. Vegetarian dancers must plan careful meal composition to reap the benefits of a plant-based diet.
2. Vegans need to manage the dietary intake of a full spectrum of micronutrients diligently, with the addition of supplemental foods, to thwart micronutrient deficiencies long-term.
3. Sufficient amounts of vitamin D, vitamin [B.sub.12], and [omega]-3 fatty acids are not present in all vegetarian and vegan diets. Dancers should seek guidance from a registered dietitian, sport nutritionist, or a dance or sports physician regarding how to incorporate these nutrients into their diet.
4. Where needed, vegetarians should seek the advice of qualified clinical dietitians to receive support with dietary planning and supplementation.
What constitutes a healthy, well planned, balanced diet fluctuates. As our knowledge of the intricacies of nutritional physiological phenomena increases, so do the details of dietary recommendations from experts globally. Table 4 provides a list of current web sources recommended by leading dietetic organizations with regard to vegetarian and vegan dietary patterns. Well planned vegetarian diets that incorporate a rich variety of plant-based foods are seen as beneficial in the prevention and treatment of certain chronic diseases. Also, as discussed above, poorly planned and managed vegetarian (particularly vegan) diets represent challenges to overall health in the long-term. Finally, the International Association for Dance Medicine & Science (IADMS), under the auspices of its education committee, offers its members a comprehensive fact sheet on general nutrition for dancers. (26) Hopefully this review serves as a compliment to that resource, providing additional information specific to the needs of the vegetarian and vegan dancer.
(1.) Bedford JL, Barr SI. Diets and selected lifestyle practices of self-defined adult vegetarians from a population-based sample suggest they are more "health conscious." Int J Behav Nutr Phys Act. 2005 Apr 13;2(1):4-11.
(2.) do Rosario VA, Fernandes R, Trindade EB. Vegetarian diets and gut microbiota: important shifts in markers of metabolism and cardiovascular disease. Nutr Rev. 2016 Jul;74(7):444-54.
(3.) Zuromski KL, Witte TK, Smith AR, et al. Increased prevalence of vegetarianism among women with eating pathology. Eat Behav. 2015 Dec;19:24-7.
(4.) Bardone-Cone AM, Fitzsimmons-Craft EE, Harney MB, et al. The inter-relationships between vegetarianism and eating disorders among females. J Acad Nutr Diet. 2012 Aug;112(8):1247-52.
(5.) Position of the American Dietetic Association and Dietitians of Canada: Vegetarian diets. J Am Diet Assoc. 2003 Jun;103(6):748-65.
(6.) Cialdella-Kam L, Kulpins D, Manore M. Vegetarian, gluten-free, and energy restricted diets in female athletes. Sports. 2016 Oct;4(4):50.
(7.) Berning JR. The Vegetarian Athlete. In: Maughn RJ (ed): Nutrition in Sport. Oxford, UK: Blackwell Science Ltd., 2000, pp. 442-456.
(8.) Craddock JC, Probst YC, Peoples GE. Vegetarian and Omnivorous Nutrition--Comparing Physical Performance. Int J Sport Nutr Exerc Metab. 2016 Jun;26(3):212-20.
(9.) Brown MA, Howatson G, Quin E, et al. Energy intake and energy expenditure of pre-professional female contemporary dancers. PLoS One. 2017 Feb;12(2):e0171998.
(10.) Brinson P, Dick F. Fit to Dance: the Report of the National Inquiry into Dancer Health and Injury. London: Calouste Gulbenkian Foundation, 1996.
(11.) Brown D, Wyon M. An international study on dietary supplementation use in dancers. Med Probl Perform Art. 2014 Dec;29(4):229-34.
(12.) Frusztajer NT, Dhuper S, Warren MP, et al. Nutrition and the incidence of stress fractures in ballet dancers. Am J Clin Nutr. 1990 May;51(5):779-83.
(13.) Le LT, Sabate J. Beyond meatless, the health effects of vegan diets: findings from the adventist cohorts. Nutrients. 2014 May;6(6):2131-47.
(14.) Garcia AL, Koebnick C, Dagnelie PC, et al. Long-term strict raw food diet is associated with favourable plasma beta-carotene and low plasma lycopene concentrations in Germans. Br J Nutr. 2007 Jun;99(6):1293-300.
(15.) Catalina Zamora ML, Bote Bonaechea B, Garcia Sanchez F, Rios Rial B. [Orthorexia nervosa. A new eating behavior disorder?]. Actas Esp Psiquiatr. 2005 Jan-Feb;33(1):66-8.
(16.) Koebnick C, Garcia AL, Dagnelie PC, et al. Long-term consumption of a raw food diet is associated with favorable serum LDL cholesterol and triglycerides but also with elevated plasma homocysteine and low serum HDL cholesterol in humans. J Nutr. 2005 Oct;135(10):2372-8.
(17.) Pedersen AB, Bartholomew MJ, Dolence LA, et al. Menstrual differences due to vegetarian and nonvegetarian diets. Am J Clin Nutr. 1991 Apr;53(4):879-85.
(18.) Berkow SE, Barnard N. Vegetarian diets and weight status. Nutr Rev. 2006 Apr;64(4):175-88.
(19.) Koebnick C, Strassner C, Hoffmann I, Leitzmann C. Consequences of a long-term raw food diet on body weight and menstruation: results of a questionnaire survey. Ann Nutr Metab. 1999;43(2):69-79.
(20.) Castelo-Branco C, Reina F, Montivero AD, et al. Influence of high-intensity training and of dietetic and anthropometric factors on menstrual cycle disorders in ballet dancers. Gynecol Endocrinol. 2009 Jan;22(1):31-5.
(21.) Challis J, Stevens A, Wilson MA. Nutrition resource paper 2016. International Association for Dance Medicine & Science. Available at: www.iadms.org/general/custom. asp?page=RPnutrition.
(22.) Berkow SE, Barnard ND. Blood pressure regulation and vegetarian diets. Nutr Rev. 2005 Jan;63(1):1-8.
(23.) Barr SI, Rideout CA. Nutritional considerations for vegetarian athletes. Nutrition. 2004 Jul-Aug;20(7-8):696-703.
(24.) Desbrow B, McCormack J, Burke LM, et al. Sports Dietitians Australia position statement: sports nutrition for the adolescent athlete. Int J Sport Nutr Exerc Metab. 2014 Oct;24(5):570-84.
(25.) Mangels R, Messina V, Messina M. The Dietitian's Guide to Vegetarian Diets: Issues and Applications (3rd ed). Sudbury, Massachusetts: Jones & Bartlett Learning, 2011.
(26.) Appleby PN, Thorogood M, Mann JI, Key TJ. The Oxford Vegetarian Study: an overview. Am J Clin Nutr. 1999 Oct;70(3 Suppl):525S-31S.
(27.) Beck S, Redding E, Wyon MA.
Methodological considerations for documenting the energy demand of dance activity: a review. Front Psychol. 2015;6:6-14.
(28.) Brown D, Wyon M. The effect of moderate glycemic energy bar consumption on blood glucose and mood in dancers. Med Probl Perform Art. 2014 Mar;29(1):27-31.
(29.) Brown DD, Challis J. Optimal nutrition for dancers. In: Wilmerding V, Krasnow D (eds): Dancer Wellness. Champaign, Illinois: Human Kinetics, 2017, pp. 163-191.
(30.) Rosell MS, Lloyd-Wright Z, Appleby PN, et al. Long-chain n-3 polyunsaturated fatty acids in plasma in British meat-eating, vegetarian, and vegan men. Am J Clin Nutr. 2005 Aug;82(2):327-34.
(31.) Van Winckel M, Vande Velde S, De Bruyne R, Van Biervliet S. Clinical practice: vegetarian infant and child nutrition. Eur J Pediatr. 2011 Dec;170(12):1489-94.
(32.) Barcelo-Coblijn G, Murphy EJ. Alpha-linolenic acid and its conversion to longer chain n-3 fatty acids: Benefits for human health and a role in maintaining tissue n-3 fatty acid levels. Prog Lipid Res. 2009 Nov;48(6):355-74.
(33.) Cormier H, Rudkowska I, Lemieux S, et al. Effects of FADS and ELOVL polymorphisms on indexes of desaturase and elongase activities: results from a pre-post fish oil supplementation. Genes Nutr. 2014 Nov;9(6):437.
(34.) Geppert J, Kraft V, Demmelmair H, Koletzko B. Docosahexaenoic acid supplementation in vegetarians effectively increases omega-3 index: a randomized trial. Lipids. 2005 Aug;40(8):807-14.
(35.) Fuhrman J, Ferreri DM. Fueling the vegetarian (vegan) athlete. Curr Sports Med Rep. 2010 Jul-Aug;9(4):233-41.
(36.) Craig WJ. Nutrition concerns and health effects of vegetarian diets. Nutr Clin Pract. 2010 Dec;25(6):613-20.
(37.) Atherton PJ, Etheridge T, Watt PW, et al. Muscle full effect after oral protein: time-dependent concordance and discordance between human muscle protein synthesis and mTORC1 signaling. Am J Clin Nutr. 2010 Nov;92(5):1080-8.
(38.) Larsson CL, Johansson GK. Dietary intake and nutritional status of young vegans and omnivores in Sweden. Am J Clin Nutr. 2002 Jul;76(1):100-6.
(39.) Koutedakis Y, Jamurtas A. The dancer as a performing athlete: physiological considerations. Sports Med. 2004;34(10):651-61.
(40.) Nieman DC. Physical fitness and vegetarian diets: is there a relation? Am J Clin Nutr. 1999 Sep;70(3 Suppl):570S-5S.
(41.) Boye J, Wijesinha-Bettoni R, Burlingame B. Protein quality evaluation twenty years after the introduction of the protein digestibility corrected amino acid score method. Br J Nutr. 2012 Aug;108(Suppl 2):S183-211
(42.) Tang JE, Moore DR, Kujbida GW, et al. Ingestion of whey hydrolysate, casein, or soy protein isolate: effects on mixed muscle protein synthesis at rest and following resistance exercise in young men. J Appl Physiol (1985). 2009 Sep;107(3):987-92.
(43.) Messina V, Mangels AR. Considerations in planning vegan diets: children. J Am Diet Assoc. 2001 Jun;101(6):661-9.
(44.) Donaldson MS. Food and nutrient intake of Hallelujah vegetarians. Nutrition & Food Science. 2001;31(6):293-304.
(45.) Doyle-Lucas AF, Akers JD, Davy BM. Energetic efficiency, menstrual irregularity, and bone mineral density in elite professional female ballet dancers. J Dance Med Sci. 2010 Dec;14(4):146-54.
(46.) Bacchi E, Spiazzi G, Zendrini G, et al. Low body weight and menstrual dysfunction are common findings in both elite and amateur ballet dancers. J Endocrinol Invest. 2013
(47.) Chartrand D, Chatfield SJ. A critical review of the prevalence of secondary amenorrhea in ballet dancers. J Dance Med Sci. 2005 Sep-Dec;9(3-4)74-80.
(48.) Warren MP, Brooks-Gunn J, Fox RP Holderness CC. Persistent osteopenia in ballet dancers with amenorrhea and delayed menarche despite hormone therapy: a longitudinal study. Fertil Steril. 2003 Aug;80(2):398-404.
(49.) Donaldson MS. Metabolic vitamin B12 status on a mostly raw vegan diet with follow-up using tablets, nutritional yeast, or probiotic supplements. Ann Nutr Metab. 2000;44(44):229-34.
(50.) Miller DR, Specker BL, Ho ML, Norman EJ. Vitamin B-12 status in a macrobiotic community. Am J Clin Nutr. 1991 Feb;53(2):524-9.
(51.) Watanabe F, Yabuta Y, Bito T, Teng F. Vitamin B12-containing plant food sources for vegetarians. Nutrients. 2014 May;6(5):1861-73.
(52.) Hunt JR, Roughead ZK. Nonhemeiron absorption, fecal ferritin excretion, and blood indexes of iron status in women consuming controlled lactoovovegetarian diets for 8 wk. Am J Clin Nutr. 1999 May;69(5):944-52.
(53.) Beck KL, Mitchell S, Foskett A, et al. Dietary intake, anthropometric characteristics, and iron and vitamin D status of female adolescent ballet dancers living in New Zealand. Int J Sport Nutr Exerc Metab. 2015 Aug;25(4):335-43.
(54.) Lee H-Y, Kim D-H, Kim S-H. An analysis of nutrients intake, related factors of anemia and bone density in ballet dancers. Indian J Sci Technol. 2015 Oct;8(25):1-6.
(55.) La Frano MR, de Moura FF, Boy E, et al. Bioavailability of iron, zinc, and provitamin A carotenoids in biofortified staple crops. Nutr Rev. 2014 May;72(5):289-307.
(56.) Weaver CM, Proulx WR, Heaney R. Choices for achieving adequate dietary calcium with a vegetarian diet. Am J Clin Nutr. 1999 Sep;70(3 Suppl):543S-8S.
(57.) Kristensen NB, Madsen ML, Hansen TH, et al. Intake of macro- and micronutrients in Danish vegans. Nutr J. 2015 Oct 30;14:115.
(58.) Elorinne A-L, Alfthan G, Erlund I, et al. Food and Nutrient Intake and Nutritional Status of Finnish Vegans and Non-Vegetarians. PLoS One. 2016 Feb 3;11(2):e0148235.
(59.) Wolman R, Wyon MA, Koutedakis Y, et al. Vitamin D status in professional ballet dancers: winter vs. summer. J Sci Med Sport. 2013 Sep;16(5):388-91.
(60.) Ducher G, Kukuljan S, Hill B, et al. Vitamin D status and musculoskeletal health in adolescent male ballet dancers a pilot study. J Dance Med Sci. 2011 Sep;15(3):99-107.
(61.) Constantini NW, Arieli R, Chodick G, Dubnov-Raz G. High prevalence ofvitamin D insufficiency in athletes and dancers. Clin J Sport Med. 2010 Sep;20(5):368-71.
(62.) U.S. Department of Argiculture, Argicultural Research Service National Nutrient Database for Standard Reference USDA. Vol Release 27. Beltsville: Nutrition Data Laboratory, 2014, pp. 1-161. Available at: www.ars.usda.gov/nutrientdata.
(63.) Appleby P, Roddam A, Allen N, Key T. Comparative fracture risk in vegetarians and nonvegetarians in EPIC-Oxford. Eur J Clin Nutr. 2007;61(12):1400-6.
(64.) Attalla K, De S, Monga M. Oxalate content of food: a tangled web. Urology. 2014 Sep;84(3):555-60.
(65.) Kohlenberg-Mueller K, Raschka L. Calcium balance in young adults on a vegan and lactovegetarian diet. J Bone Miner Metab. 2003;21(1):28-33.
(66.) Haddad EH, Berk LS, Kettering JD, et al. Dietary intake and biochemical, hematologic, and immune status of vegans compared with nonvegetarians. Am J Clin Nutr. 1999 Sep;70(3 Suppl):586S-93S.
Derrick D. Brown, MSc(Hons)
Derrick D. Brown, MSc(Hons), University of Bern, Institute for Sport Science, Bern, Switzerland; and National Centre for Performing Arts, Arnhem, the Netherlands.
Correspondence: Derrick D. Brown, MSc(Hons), Onderlangs 9, 6812 CE Arnhem, The Netherlands; firstname.lastname@example.org.
Caption: Figure 1 Classification of vegetarian dietary patterns.
Caption: Figure 2 Plant-based iron sources.
Table 1 Vitamins and Minerals Relevant to Vegetarian Diet Micronutrient Vegetarian and Vegan Sources Vitamins Vitamin [B.sub.12] Foods of animal and plant origin, including milk, (cyanocobalamin) cheese, yogurt, seaweed, yeast Vitamin D Eggs, fortified foods, soy milk and cereals, action of (cholecalciferol, sunlight on skin ergocalciferol) Minerals Calcium Milk, cheese, yogurt, fortified soy products, nuts and seeds, green vegetables, dried fruit Iodine Eggs, dairy, iodized salt, sea vegetables; it is recommended that vegans consume iodized salt or kelp Iron Fortified breakfast cereals, bread, textured vegetable protein, legumes, pulses, dried beans, soy foods and meat alternatives, nuts, dried fruits and green leafy vegetables; vitamin C (ascorbic acid) enhances iron absorption Zinc Legumes, pulses, whole grains, cereals, nuts, seeds, soy and dairy products, Vitamin C along with the soaking of beans, grains and seeds enhances zinc bioavailability Micronutrient Function and Comments Vitamins Vitamin [B.sub.12] Coenzyme essential for healthy nerve tissue and the (cyanocobalamin) metabolism of protein, fat, and carbohydrate. Also, important for the prevention of anemia. Negligible nutrient rich vegan sources. Fortified foods Vitamin D Essential for bone growth and maturation, promotes (cholecalciferol, bone mineralization, aids in absorption of calcium ergocalciferol) and maintaining neural, cardiovascular, and immune systems. Minerals Calcium Essential for blood clotting, maintaining the neural system, vitamin D metabolism, and bone structure Iodine Enzyme synthesis important for thyroid hormonal balance Iron Required for synthesis of hemoglobin and myoglobin; an essential mechanism in transport and delivery of oxygen within blood and muscles Zinc Prevent low mood; allow normal wound healing; involved in the immune system, appetite regulation, and enzyme synthesis. Table 2 Vitamin D Found in Foods Kcal in Vitamin D in Standard Standard Standard Portion Food Portion Size Portion ([micro]g) Liquids and Fat Milk (non-fat, 1% and 2%) (*) 1 cup 83-122 2.9 Soymilk (*) 1 cup 109 2.9 Whole Chocolate Milk (*) 1 cup 208 3.2 Orange Juice (fortified) 1 cup 117 2.5 Almond milk (all flavors) (*) 1cup 91-120 2.4 Margarine (regular, 80% fat, composite, stick, 1 tablespoon 75-100 1.5 with salt) (*) Yogurt and Soft Cheeses Including Dairy Alternatives Yogurt (various types and flavors) (*) 8 ounces 98-254 2.0-3.0 Plant-based Vitamin D rich foods Fortified Ready-to-Eat Cereals (various) (*) 1/3 - 1 1/4 cup 74-247 0.2-2.5 Mushrooms (Chanterelle, Raw) ([dagger]) 1/2 cup 10 1.4 Mushrooms (Portabella, Grilled) ([dagger]) 1/2 cup 18 7.9 Vitamin D in Standard Portion Food (IU) Liquids and Fat Milk (non-fat, 1% and 2%) (*) 116 Soymilk (*) 116 Whole Chocolate Milk (*) 128 Orange Juice (fortified) 100 Almond milk (all flavors) (*) 96 Margarine (regular, 80% fat, composite, stick, 60 with salt) (*) Yogurt and Soft Cheeses Including Dairy Alternatives Yogurt (various types and flavors) (*) 80-120 Plant-based Vitamin D rich foods Fortified Ready-to-Eat Cereals (various) (*) 8-100 Mushrooms (Chanterelle, Raw) ([dagger]) 56 Mushrooms (Portabella, Grilled) ([dagger]) 316 (*) Vitamin D fortified. ([dagger]) Exposed to ultraviolet light. Source: U.S Department of Agriculture, Agricultural Research Service, Nutrient Data Laboratory. 2014. USDA National Nutrient Database for Standard Reference, Release 27. Available at: www.ars.usda.gov/nutrientdata. Table 3 Plant-Based Calcium Sources (62,65) 300 mg Calcium fortified citrus or vegetable juice 8 fluid ounces (0.24 L) Plant-based fortified milk (soy, nut, hemp, cashew, rice) 8 fluid ounces (0.24 L) Pak soi and bok choy 1 head (approximately 850 g) 200 mg Breakfast cereal (calcium fortified) 1 dry ounce (28 g) Tofu (prepared in calcium-sulphate) 1/2 cup (28 g) Blackstrap molasses 1 tablespoon 100 mg Soybeans (cooked) 1/2 cup (28 g) Chickpeas (boiled, canned) 7 ounces (210 g) Kale (raw) 1 cup (67 g) Table 4 Useful Online Sources Relating to Vegetarian Diets Vegetarian Nutrition Dietetic Practice Group vegetariannutrition.net/National Health Service ( NHS) www.nhs.uk/Livewell/Vegetarianhealth/Pages/Vegandiets.aspx U.S Department of Agriculture Choose my Plate (USDA) https://www.choosemyplate.gov/tips-vegetarians The Vegetarian Society of the United Kingdom Limited https://www.vegsoc.org/facts/iron Medline Plus, Vegetarian Diet https://medlineplus.gov/vegetariandiet.html The Vegan Society (Vitamin B12) https://www.vegansociety.com/resources/downloads The Vegetarian Resource Group www.vrg.org The Vegetarian Society of South Africa www.vegsoc.org.za The Vegetarian Society of Northern Ireland https://www.vegsoc.org/Nirelandgroups
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|Author:||Brown, Derrick D.|
|Publication:||Journal of Dance Medicine & Science|
|Date:||Jan 1, 2018|
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