2006 Vegetarian Diets- Nutritional Considerations for Athletes

8/9/2019 2006 Vegetarian Diets- Nutritional Considerations for Athletes

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Sports Med 2006; 36 (4): 293-305LEADING ARTICLE 0112-1642/06/0004-0293/$39.95/0

© 2006 Adis Data Information BV. All rights reserved.

Vegetarian DietsNutritional Considerations for Athletes

Angela M. Venderley and Wayne W. Campbell

Department of Foods and Nutrition, Purdue University, West Lafayette, Indiana, USA

The quality of vegetarian diets to meet nutritional needs and support peak Abstractperformance among athletes continues to be questioned. Appropriately planned

vegetarian diets can provide sufficient energy and an appropriate range of carbo-

hydrate, fat and protein intakes to support performance and health. The acceptable

macronutrient distribution ranges for carbohydrate, fat and protein of 45–65%,

20–35% and 10–35%, respectively, are appropriate for vegetarian and

non-vegetarian athletes alike, especially those who perform endurance events.

Vegetarian athletes can meet their protein needs from predominantly or exclusive-

ly plant-based sources when a variety of these foods are consumed daily and

energy intake is adequate. Muscle creatine stores are lower in vegetarians than

non-vegetarians. Creatine supplementation provides ergogenic responses in both

vegetarian and non-vegetarian athletes, with limited data supporting greater

ergogenic effects on lean body mass accretion and work performance for vegetari-ans. The potential adverse effect of a vegetarian diet on iron status is based on the

bioavailability of iron from plant foods rather than the amount of total iron present

in the diet. Vegetarian and non-vegetarian athletes alike must consume sufficient

iron to prevent deficiency, which will adversely affect performance. Other nutri-

ents of concern for vegetarian athletes include zinc, vitamin B12 (cyanocobala-

min), vitamin D (cholecalciferol) and calcium. The main sources of these nutrients

are animal products; however, they can be found in many food sources suitable for

vegetarians, including fortified soy milk and whole grain cereals. Vegetarians

have higher antioxidant status for vitamin C (ascorbic acid), vitamin E (tocopher-

ol), and β-carotene than omnivores, which might help reduce exercise-induced

oxidative stress. Research is needed comparing antioxidant defences in vegetarianand non-vegetarian athletes.

Vegetarian diets are receiving increased scientif- cals and lower in saturated fat and cholesterol than

ic scrutiny and popularity among the general public omnivorous diets.[1-3] Numerous studies have report-

for potential health-promoting benefits. The Ameri- ed diverse health benefits of consuming a vegetarian

can Dietetic Association (ADA) states that well diet, including lower risk for heart disease, hyper-

planned vegetarian diets are healthful, nutritionally tension, diabetes mellitus, obesity and some types of

adequate, and provide health benefits in the preven- cancers.[4-13] Other factors considered when choos-

tion and treatment of certain diseases.[1]

Vegetarian ing a vegetarian diet may include environmentaldiets tend to be higher in complex carbohydrates, issues, religious and moral beliefs.[14] Recent esti-

fibre, fruits, vegetables, antioxidants, phytochemi- mates suggest that approximately 2.5% of American


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294 Venderley & Campbell

adults and 4% of Canadian adults consume vegetari- tion of animal-based foods, and to possibly elimi-

an diets.[1] nate the use of some, especially red, meats. This

eating style typically has been referred to as ‘semi-A small proportion of athletes have adopted a vegetarian’. While this term has gained popularity invegetarian diet with the goal of obtaining health,

its use, it is ambiguous and should be avoided sincetraining and performance benefits.[15,16] Endurance

the consumption of meat, no matter how little, isathletes, especially triathletes, runners and cyclists,

carnivorous.may consume a vegetarian diet in order to meet

increased carbohydrate needs and to assist in weight

control.[14] In a National Runners’ Health Study1.1 Lacto-Ovo-Vegetarian Diet

survey of 9242 runners, investigators found 351

vegetarian runners (3.8%).[17] Of those, 289 wereA lacto-ovo-vegetarian diet is the most commonlacto-vegetarians and 62 were vegans. Several well

type that vegetarians follow.[14,15,18] The plant-basedknown athletes have also adopted vegetarian eating

diet excludes meats, poultry and fish, but includespatterns, including Dave Scott (six-time Ironmanmilk, other dairy products and eggs. Nutritionalwinner), Andreas Cahling (champion bodybuilder),deficiencies are less commonly seen with this eatingSurya Bonaly (French Olympic figure skater), Pavopattern when an individual consumes a variety of Nurmi (long-distance runner with 20 world records)plant foods, egg and dairy products. Dairy productsand Billy Jean King (tennis champion).[18]provide good sources of protein, calcium, vitamin D

The ADA supports that the energy and macronu-(cholecalciferol) and vitamin B12 (cyanocobala-trient needs of competitive athletes can be metmin), the nutrients typically of concern in a vegetari-

through a vegetarian diet.[19] Yet, concern existsan diet. While most vegetarian diets generally con-

among coaches and trainers that a vegetarian diettain lower amounts of fat than omnivorous diets, it is

may not fully support the nutritional requirementsadvisable for vegetarians to balance the use of full-

and performance goals of athletes, especially when and lower fat dairy products and to maintain total fatthey perform high-intensity sports.[20] The purpose

intakes within the range of 20–35% of daily energyof this article is to describe different types of vegeta-

need.[14,15,18,22]rian diets, to highlight nutritional considerations for

There are two variations of the lacto-ovo-vegeta-vegetarian athletes, and to discuss the potential im-rian diet: a lacto-vegetarian and an ovo-vegetarianpact of vegetarian diets on athletic performance. Asdiet. A lacto-vegetarian diet excludes eggs and eggsuch, this review focuses on the nutritional implica-products and an ovo-vegetarian diet excludes milk tions of vegetarianism and potential effects on ath-and milk products.[14,18,22]letic performance, and complements previous relat-

ed reviews;[16,20,21] it is not meant to be a comprehen-

sive meta-analysis of the topic.

1. Types of Vegetarian Diets

A vegetarian diet is a plant-based diet that con-

sists mostly of fruit, vegetables, grains, legumes,

nuts and seeds, and excludes beef, pork, poultry and

fish. There are several different types of vegetarian

diets with each one varying slightly (table I).[14,15,18]

Two main categories are lacto-ovo-vegetarian and

vegan.

The potential health benefits of a vegetarian diethave prompted some people to reduce the consump-

Table I. Types of vegetarian diets

Type Food patterns

Lacto-ovo- Excludes meat, poultry and fish, but includes

vegetarian milk, other dairy products and eggs

Lacto-vegetarian excludes eggs and egg

products

Ovo-vegetarian excludes milk and milk products

Vegan Excludes meat, poultry, fish, eggs, dairy

products, gelatin, honey and animal-derived

additives

Macrobiotic excludes some fish, eggs, dairy

products, tropical fruits, processed sweeteners

and vegetables of the nightshade family such as

potatoes, tomatoes, eggplant and peppers

Fruitarian predominately consumes raw or driedfruits


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Vegetarian Diets and Athletes 295

1.2 Vegan Diet athlete’s needs. However, some athletes, especially

those who choose to consume a vegan diet, may beA person practicing a vegan diet avoids all challenged to consume sufficient quantities of food

animal products including beef, poultry, pork, fish, to meet their energy needs if their food choices haveeggs, dairy products, gelatin, honey and animal- lower energy density (lower fat and higher fibre).derived food additives. The diet consists primarily Very high fibre diets will slightly decrease energyof fruits, vegetables, grains, legumes, nuts and availability due to a reduction in metabolisable ener-seeds. A person who consumes a vegan diet may be gy (i.e. the amount of ingested energy that is di-at increased risk of inadequate intakes of some nutri- gested, absorbed and available for use or storage).ents that are mainly found in animal products; these Energy intakes among vegetarians are also typicallyinclude vitamin B12, vitamin D, calcium and zinc.[18] lower than non-vegetarians.[18,23] The joint position

The macrobiotic diet is a type of vegan diet that statement on nutrition and athletic performancefew vegetarians follow. It is based mainly on grains, from the ADA, the American College of Sports

vegetables and legumes with emphasis on rice and Medicine (ACSM) and the Dietitians of Canadasea vegetables.[18] It excludes beef, pork, poultry, (DC)[19] emphasises that all athletes, including thosesome fish, eggs, dairy products, tropical fruits, who consume a vegetarian diet, must consume suffi-processed sweeteners and vegetables of the night- cient energy to support optimal performance, main-shade family such as potatoes, tomatoes, eggplant tenance of lean tissue, and immune and reproductiveand peppers. Nuts, fruits and seeds are consumed in functions.moderation and fish may be consumed in limited There are several ways to increase the energyamounts, if at all. intake of a vegetarian athlete.[14,18] The athlete can

A fruitarian diet is another form of vegan diet and eat more frequent meals and snacks, and includeleast followed among vegetarians.[18] It is based meat alternatives (e.g. textured vegetable protein,

predominately on the consumption of raw or dried tempeh and tofu), dried fruit or fruit juices, honeyfruits, although it can include some nuts, seeds and and jams, avocados, nuts, nut butters and seeds invegetables such as squash, tomatoes, eggplants, pep- their diet. Coaches and trainers are encouraged topers and avocados. Deficiencies in protein and calci- periodically monitor the weight of a vegetarian ath-um are among some of the nutrient concerns with lete to ensure that energy needs are being met,the diet. Needs for calcium and protein can be met if especially if lean body mass is favoured in theirlarge amounts of nuts and seeds are consumed. sport.[19] To help avoid gastrointestinal discomfort,However, this type of diet is generally not recom- new vegetarian athletes should continue to includemended and would be a challenge to plan in order to energy-dense, lower fibre foods and to graduallymeet nutrient needs of an individual.[18] introduce higher fibre foods into their diet over the

course of 3–4 weeks.2. Nutritional Considerations for AthletesWho Consume Vegetarian Diets 2.2 Macronutrient Distribution

The ACSM, ADA, DC joint position statement2.1 Energyappropriately emphasises that specific recommenda-

Athletes have higher energy needs because of the tions for the macronutrient distribution of an indi-

increased demands of physical activity.[18,19] Energy vidual athletes’ diet will depend on the persons body

needs range from 2000 to 6000 kcal/day or more size (weight and height), body composition, sport-

depending on the athlete’s body size, body composi- specific energy needs and sex.[19] Provided that suf-

tion, sex, training programme, and type and intensi- ficient energy is consumed to meet the energy de-

ty of the sport they perform.[18,19] Vegetarian diets mands of higher intensity training and to maintainare capable of providing sufficient energy to meet an bodyweight, a vegetarian diet is well suited to pro-


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vide the 7–8g carbohydrate and 1.2–1.7g protein/ in intake to 20% of energy (200g protein/day, 2.67g

protein/kg • day), which greatly exceeds the athleteskg • day recommended.[19,24] Vegetarians, especially

protein needs.vegans, consume the majority of their energy in the

form of carbohydrate.[2,18] Summarising dietary data

2.3 Proteinfrom 63 research studies, Messina and Messina[18]

reported that among the general public, the carbohy-Vegetarian diets generally contain less proteindrate intake of vegans ranges from 50–65% of ener-

than omnivorous diets. Summarising dietary datagy and lacto-ovo vegetarians ranges from 50–55%,from 63 research studies, Messina and Messina[18]compared with ≤50% for non-vegetarians. Nie-reported that protein intakes among vegans, lacto-man[24] suggested that most endurance athletes, es-ovo-vegetarians and omnivores ranged frompecially those training >60–90 min/day, should con-10–12%, 12–14% and 14–18% of energy, respec-sume between 60–70% of energy as carbohydrate totively. Coaches, trainers and athletes continue tomaximise muscle glycogen synthesis, and submitted

question whether a vegetarian diet can provide ade-that a vegetarian diet may be an ‘optimal’ diet forquate protein to meet the increased dietary needs of athletes because it includes numerous higher carbo-highly trained athletes.[26] The ADA and DC 2003hydrate, lower fat foods and adequate protein.position paper on vegetarian diets states that typical

The ACSM, ADA and DC joint position state- protein intakes of lacto-ovo-vegetarians and vegansment supports that sufficient carbohydrate intake is appear to meet or exceed requirements and athletesrequired to enhance endurance performance, but can meet their protein needs by consuming vegetari-cautions that making dietary recommendations an diets.[1] It was once thought that various plantbased on proportions of macronutrient intakes may proteins had to be consumed in the same meal inbe misleading for some athletes, especially those order to provide all essential amino acids; however,with very high or low energy needs, and may not

complementary meal planning is not re-result in ‘optimal’ nutrient intakes. For the general quired.[1,16,19,27] A vegetarian diet can supply all es-public, the acceptable macronutrient distribution sential and nonessential amino acids from plantranges for carbohydrate, fat and protein are 45–65%, foods alone if a variety of these foods are consumed20–35% and 10–35%, respectively.[25] These ranges over the course of a day and energy intake is ade-are considered acceptable for vegetarian and non- quate.vegetarian athletes alike, with the understanding that While all athletes may benefit from careful dieta-a modest 10% increase in protein intake is recom- ry planning to support athletic performance, athletesmended to adjust for the incomplete digestion of who consume a vegan diet may require special con-plant proteins.[19] sideration to ensure adequate protein intake. There

It is important to understand that the suggested are a wide variety of high-protein vegetarian food

10% increase in protein intake is not the same as a and beverage products now on the market to assist

10% increase in energy intake from protein. For vegetarian athletes to meet their protein needs con-

veniently. Proteins in egg, dairy and soy (tofu,example, consider a 75kg endurance athlete who

tempeh and textured vegetable protein) are all high-requires 4000 kcal energy/day and consumes a vege-

quality and provide the essential amino acids neces-tarian diet that contains 10% of energy as protein

sary for protein synthesis. Other sources of protein(400 kcal/day, 100g protein/day, 1.33g protein/

typically incorporated into vegetarian diets includekg • day). To increase protein intake by 10%, the

legumes, dried beans, peas and nuts.athlete would need to consume 10 more grams of

protein per day, which represents about 40 kcal/day The recommended dietary allowance (RDA) for

energy and would increase total protein intake to protein is 0.8g protein/kg • day for all apparently

1.47g protein/kg • day. In contrast, a 10% increase healthy adults, with no increase for persons whoin energy intake as protein would double total prote- habitually exercise.[25] The Food and Nutrition


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Board stated that “In view of the lack of compelling vegetarian office workers with similar physical ac-

evidence to the contrary, no additional dietary prote- tivity levels to the vegans. The assessments included

in is suggested for healthy adults undertaking resis- forced expiratory volume and forced vital capacity

tance or endurance exercise.”[25] This view contrasts by spirometry, cardiovascular response to submax-

with the ACSM, ADA and DC committee,[19] and imal exercise on a cycle ergometer, and estimates of others,[28,29] who suggested that the protein needs of thigh muscle width from circumference and skinfoldwell trained endurance and strength athletes were measurements. There were no differences in thehigher than for sedentary persons. The ACSM, ADA variables measured in vegans compared with theand DC committee specified that endurance and non-vegetarians. The results showed that a veganstrength-training athletes may have protein needs of diet does not impair the physiological response to1.2–1.4 and 1.6–1.7 g/kg • day, respectively.[19] The submaximal exercise.[33]

higher protein need of athletes is considered neces-Hanne et al.[34] studied the effects of different

sary to support the modestly increased use of protein

vegetarian diets on physical fitness. Various fitnessas an energy source during exercise (amino acid parameters were used to compare vegetarian (31oxidation), and the needs for amino acids for the

lacto-ovo-vegetarians, 13 lacto-vegetarians and 5repair of damaged muscle following exercise and for

vegans) with non-vegetarian athletes matched formuscle hypertrophy. When evaluating these appar-

age, sex, body size and type of athletic activity. Noently conflicting recommendations, it is important to

significant differences in fitness parameters wereemphasise that the higher protein recommendations

found between vegetarian and non-vegetarian ath-proposed by the ACSM, ADA and DC committee

letes in a variety of physical fitness, anthropometricare for highly trained, elite athletes. Consistent with

and metabolic measures, including aerobic and ana-the Food and Nutrition Board statement, there is

erobic capacity, hand grip, back strength,little scientific support for recreational and non-elite

haemoglobin, total serum protein and pulmonary

athletes to consume more protein than sedentary function. While the results of this study generallyindividuals.[30,31] However, the adequacy of the

support that consumption of a vegetarian diet doesRDA to ‘optimise’ athletic performance continues

not impair the capacity to perform aerobic and ana-to be questioned and requires further evaluation.[32]

erobic exercise, the study also underscores the im-

portance of defining and controlling the types of 3. Vegetarian Diets and Performance

subjects studied and other experimental design is-

sues.[15] It is difficult to apply these findings whenIn his 1999 review, Nieman[20] documented the

the subjects consumed a wide variety of diets forfindings from about eight cross-sectional and short-

which the energy and macronutrient contents wereterm intervention studies from the 1970s, 1980s and

not documented, the subjects performed numerousearly 1990s, and concluded that “… a vegetarian

types of athletic activities ranging from long-dis-diet, even when practiced for several decades, istance running to football to basketball, and the sub-neither beneficial nor detrimental to cardiorespirato-

ject age range was 17–60 years.ry endurance, especially when carbohydrate intake,Raben et al.[35] studied the effect of a lacto-ovo-age, training status, bodyweight, and other con-

vegetarian diet and a mixed diet with meat on endur-founders are controlled for.” Among these studies,

ance performance in male athletes. The study groupCotes et al.[33] investigated the effects of a vegan diet

consisted of eight well trained male endurance ath-on the physiological response to submaximal exer-

letes with a mean maximal oxygen uptake (V̇O2max)cise, not in athletes, but in sedentary individuals.

of 67 mL/kg/min. The athletes were fed a lacto-ovo-The study group consisted of 14 women who con-

vegetarian diet for 6 weeks and a mixed diet for 6sumed a vegan diet supplemented with vitamin B12,

weeks. An aerobic endurance test was performed on66 non-vegetarian housewives with social back-grounds comparable to the vegans, and 20 non- subjects using a cycle ergometer or treadmill after 0,


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3 and 6 weeks of consuming each diet. Average protein. Whole-body density, fat-free mass, and

V̇O2max was 4.93 L/min before subjects consumed whole-body muscle size increased in the meat diet

the mixed diet and 4.83 L/min before the vegetarian group and decreased in the vegetarian diet group.

diet. After consuming the diets for 6 weeks, average Type II muscle fibre area of the vastus lateralis

V̇O2max was 4.90 L/min with the mixed diet and muscle increased with strength training in all men,

4.79 L/min with the vegetarian diet. No significant consistent with a hypertrophy response, with a trend

changes in endurance performance were found after for the increase to be greater in the meat diet group

6 weeks when athletes were fed either a mixed diet (16.2 ± 4.4%) than in the vegetarian diet group (7.3with meat or a lacto-ovo-vegetarian diet. The results ± 5.1%). Gains in maximal muscle strength withfrom the study showed that a lacto-ovo-vegetarian training were not influenced by the diet consumed.diet does not affect endurance performance.[35] The results showed that consuming a diet containing

meat contributed to greater gains in fat-free massIn their 2004 review of the nutritional considera-and muscle hypertrophy with strength training than

tions for vegetarian athletes, Barr and Rideout[21]

did consuming a lacto-ovo-vegetarian diet.[39] Cau-noted that a paucity of data exist on the effects of ation is warranted when interpreting these resultsvegetarian diet on athletic performance from wellbecause the study diets were not completely con-controlled, amply powered research studies, and thattrolled and the men assigned to the vegetarian dietfew (if any) have been reported since the 1999group tended to decrease their energy and proteinreview by Nieman.[20] We concur that better re-intakes over time, which might have influenced thesearch is needed to directly compare athletic per-adaptive responses to training.[21]formance of vegetarians and non-vegetarians since

few well conducted studies exist.[14,15] In a subsequent study from the same research

group with better dietary control, Haub et al.[40,41]We are unaware of any published research ad-

noted no differences in muscle strength, power anddressing whether consumption of a vegetarian diet size gains after a 12-week period of strength traininginfluences body composition, muscle hypertrophy,in older men who consumed an omnivorous (beef-and muscle strength and power in resistance-trainedcontaining) or lacto-ovo-vegetarian (soy-contain-athletes. However, at the other end of the muscleing) diet. Both groups of men were counselled tosize and strength spectrum, this issue has been ad-consume a basal lacto-ovo-vegetarian diet and weredressed in sedentary older men. Campbell et al.[36,37]

provided 0.6g protein/kg • day from portioned quan-observed that older men and women who weretities of beef or soy foods, with total protein intakeshabitualised to a lacto-ovo-vegetarian diet did notnot different between groups (129–144% of theexperience measurable muscle hypertrophy after aRDA).[40] The beef group experienced increases in12-week strength training programme. The pro-serum high-density lipoprotein cholesterol (HDL),gramme (three sets of eight repetitions at 80% of low-density lipoprotein cholesterol (LDL) and totalmaximal strength capacity for a variety of largecholesterol (CHOL), with no changes in triacylg-muscle group exercises, 3 days/week) had previous-lycerol (TG), the CHOL/HDL ratio, or the TG/HDLly been documented to cause muscle hypertrophy inratio. In contrast, the soy group did not experienceolder men who consumed an omnivorous diet.[38]

any changes in the lipid-lipoprotein profile parame-Campbell et al.[39] then directly compared the effect

ters during training. Among all subjects, differencesof a meat-containing diet (beef, poultry, pork and

in the saturated fat/fibre ratio and cholesterol/fibrefish) and a lacto-ovo-vegetarian diet on muscle size

ratio and increases in carbohydrate intake over timeand whole-body composition in older men. During

were the main predictors of changes in lipid-lipopro-the 12-week period, nine men were fed a meat-

tein profile parameters. Collectively, the results of containing diet that provided 125% of the RDA

these studies[36,37,39-41] suggest that the quantity of from protein and ten men were fed a lacto-ovo-vegetarian diet that provided 100% of the RDA for protein rather than the source of protein contributed


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to the variations in body composition and muscle serves as an energy source during exercise. During

hypertrophy responses to strength training among intense exercise, creatine phosphate is broken down

older men who consumed omnivorous versus lacto- to creatine and phosphate by the enzyme creatine

ovo-vegetarian diets. The results also suggest the kinase, and the high-energy phosphate molecule

need to include assessments of various health-relat- rapidly combines with adenosine diphosphateed parameters, such as lipid-lipoprotein profile, (ADP) to form adenosine triphosphate (ATP). Thewhen assessing the relative efficacy of omnivorous rapid resynthesis of ATP during exercise helps pro-versus vegetarian diets with exercise training. Final- vide a steady energy source for muscle contraction.ly, these results underscore that nutrition-exercise Creatine phosphate concentration declines rapidlyinteractions may affect the health and adaptations to during maximal exercise and its depletion preventstraining of a wide range of people, from previously adequate ATP production and the body’s inability tosedentary older men to elite athletes. match ATP demand and supply contributes to mus-

cular fatigue. Elevated muscle creatine content in-

4. Creatine creases the rate at which creatine phosphate is re-synthesised during recovery from exercise and may

Creatine supplementation has gained popularity enhance exercise performance and recovery time forover the years among professional and recreational an athlete during short repeated bouts of maximalathletes due to its possible effects on enhancing exercise. For this reason, many athletes, especiallyexercise performance and body composition vegetarian athletes, may consider using creatinechanges with training. As recently reviewed by supplementation to increase muscle creatine stores.Volek and Rawson,[42] hundreds of research studies

Creatine supplementation regimens often includehave been conducted and numerous review papersingestion of 20–25g creatine/day for 3–7 days,written on whether creatine supplementation func-clearly an intake not possible via the diet. A lower

tions as an ergogenic aid for metabolic adaptations dose of 3 g/day over approximately 4 weeks also hasto acute exercise and chronic training, as well asbeen documented to significantly elevate musclesports performance. The preponderance of data sup-creatine concentration.[45] Creatine supplementationport that creatine supplementation is ergogenic, es-may increase muscle creatine concentration bypecially for short-term, high-intensity exercise[43]

>30%, although variability in this response has beenand resistance-training-induced gains in lean bodynoted, with initial muscle creatine content an impor-mass, maximal muscle strength and weightliftingtant factor of supplementation-related creatine up-performance.[42]

take.[46] While it is possible to obtain up to 3 g/day of The major role of creatine in the body is increatine by consuming very high quantities of striat-energy metabolism.[18,21,44] Creatine is synthesiseded tissue foods, few people are likely to consumeendogenously from the precursor amino acids argi-this amount of meat. Raw beef contains about 30nine, glycine and methionine at a rate of about 1 g/ mmol creatine/kg dry weight.[47] However, exposureday. Dietary intake of creatine-containing foods,to high temperatures for long periods of time cataly-predominately meat, fish and poultry, also provideses the conversion of creatine to creatinine. Thus,about 1 g/day. Greater than 90% of the total bodydepending on how meats are cooked, there might bepool of creatine is located in skeletal muscle where ita large decrease in the creatine content (


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which has been hypothesised to make them more divided into four groups: (i) vegetarian with creatine

responsive to supplementation-related improve- supplementation (16.8g creatine/day during a 7-day

ments in sports performance. loading phase and 4.2g creatine/day during a 49-day

maintenance phase); (ii) vegetarian with placeboResearch in young adults documents that con-

supplementation; (iii) non-vegetarian with creatinesumption of lacto-ovo-vegetarian[48] and vegan[46]

supplementation (supplementation same as vegetari-diets decreases muscle total creatine concentration.

an + creatine); and (iv) non-vegetarian with placeboLukaszuk et al.[48] reported decreased muscle total

supplementation. The study results showed that: (i)and free creatine concentrations in 16 men who

habitual vegetarians (lacto-ovo-vegetarian or vegan)consumed for 3 weeks a lacto-ovo-vegetarian diet

had lower concentrations of intramuscular total cre-that contained 1.5g protein/kg • day, compared with

atine and phosphocreatine concentrations than non-unchanged concentrations in 16 men who continued

vegetarians at baseline; (ii) the vegetarians exper-to consume an omnivorous diet that provided com-

ienced greater gains in muscle total creatine andparable quantities of protein. Subsequent supple-

phosphocreatine with creatine supplementation; andmentation with 0.3g creatine/kg • day and 20g(iii) the post-supplementation total creatine andPolycose® 1 for 5 days increased muscle total crea-

phosphocreatine concentrations were not differenttine among all subjects, with no difference in post-

between diet groups. Greater increases in bench-supplementation creatine concentration between di-

press strength, type II muscle fibre area and whole-et groups. The comparable muscle creatine concen-

body lean mass were observed in both creatinetration between vegetarians and omnivores post-

groups compared with the placebo groups. The veg-supplementation suggests that initially lowering

etarian + creatine group had greater increases inmuscle creatine concentration by consuming a vege-

muscle total creatine, lean tissue mass and totaltarian diet is not a viable strategy to achieve a higher

work performance for knee flexion and extensionmaximum concentration with supplementation.

than the non-vegetarian + creatine group. TheseLukaszuk et al.[48] speculated that the reduction infindings suggest that creatine supplementation ismuscle total creatine concentration with the onset of ergogenic and that vegetarians experience greaterconsuming a vegetarian diet might be due to de-metabolic, body composition and performance re-creased methionine, glycine and arginine intakes,sponses to creatine supplementation.amino acids required for endogenous creatine syn-

thesis. This interpretation should be viewed with Shomrat et al.[51] examined the effect of creatine

caution because vegetarian diets are generally con- supplementation on anaerobic exercise performance

sidered to provide all essential amino acids, and during three, 20-second maximal cycling tests

these subjects consumed almost twice the RDA for (modified Wingate anaerobic test) in seven vegetari-

protein. The amino acid content of the diets provid- ans and nine omnivores who consumed 21 g/day of

ed to these subjects were not presented in the report. creatine per day for 6 days, compared with eightIt is also known that consumption of a creatine-free omnivores who consumed a glucose placebo. Maxi-

vegetarian diet fully activates, and meat consump- mal exercise performance was determined before

tion suppresses, the enzyme glycine amidinotrasfer- and after creatine supplementation. Creatine supple-

ase, which is the rate-limiting enzyme for creatine mentation increased body mass ~1.1kg and mean

synthesis in the kidney.[49] work performance by ~5% for both diet groups, and

Burke et al.[50] reported similar findings in a peak work performance by ~5% in the omnivorous

double-blind study with young men and women who group only. These parameters were not changed

were recreational athletes. Eighteen vegetarians and with supplementation in the glucose-control group.

24 non-vegetarians participated in an 8-week resis- The results of this study support that creatine sup-

tance-training programme. Subjects were randomly plementation is ergogenic for both vegetarians and

1 The use of trade names is for product identification purposes only and does not imply endorsement.


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omnivores, and do not support that the habitual lower ferritin and higher transferrin concentrations,

consumption of a vegetarian diet lowers maximal which indicate lower iron stores but a higher amount

exercise capacity. being transported in the blood. Ferritin concentra-

tion in vegetarians was half that of non-vegetarians.

5. Iron Although vegetarians had a higher iron content inthe blood, iron stores were reduced.[55,57] These re-

Iron is critical in sports nutrition. It is used for the sults suggest that vegetarian diets provide amplesynthesis of haemoglobin and myoglobin, essential total iron but absorption, especially non-haeme ironcomponents in the transport and delivery of oxygen absorption, may be impaired due to inhibitors suchto the muscles.[15,18,52,53] Athletic training, especially as phytate and fibre, thus reducing iron stores andendurance training, and competition tend to reduce increasing the risk for iron-deficiency anaemia. Vi-iron stores.[15,18,52-54] Iron stores are also depleted tamin C (ascorbic acid), present in fruits and vegeta-when iron needs are not adequately met in the di- bles, can largely counteract the effects of iron inhibi-et.[15,18,52,53] tors and may provide a means for vegetarian athletes

Vegetarian diets generally contain as much or to partially offset the effects of reduced iron bioavai-more total iron than omnivore diets.[18,27,55] Total lability.[1,18,20,27,55]iron intake is usually higher in vegans than in lacto-

Iron-deficiency anaemia may be a detriment toovo-vegetarians because dairy foods contain rela-performance, especially aerobic performance, sincetively little iron. Lacto-ovo-vegetarian athletes gen-iron is critical in oxidative energy metabo-erally consume about the same amount of total ironlism.[15,52,53] However, iron deficiency anaemia isas non-vegetarian athletes.[18] Concerns over therare in vegetarian athletes and a mild iron deficiencyiron status of vegetarian athletes are usually basedis not likely to impair performance.[16,20] Messinaon the bioavailabilty of iron from plant foods ratherand Messina[18] reported that only 10% of athletes

than the amount of total iron present in a vegetarian have anaemia and that it is more commonly founddiet.[3,15,18,20] Plant foods contain only non-haemeamong endurance athletes. A study by Snyder etiron, which is less absorbed than haeme iron foundal.[58] documented lower iron stores in nine femalein animal products. An individual’s iron status, thelong-distance runners who consumed a restrictedamount of total dietary iron consumed, and themeat (semi-vegetarian;


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Table II. Micronutrients of special concern for vegetarian athletes

Micronutrient Function Sources in a vegetarian diet and comments

Iron Required for synthesis of haemoglobin and Fortified breakfast cereals, bread, textured vegetable

myoglobin, essential components in transport and protein, legumes, dried beans, soy foods and meatdelivery of oxygen within blood and to the muscles alternatives, nuts, dried fruits and green leafy vegetables,

vitamin C (ascorbic acid) enhances iron absorption

Zinc Involved in immune function, protein synthesis and Legumes, whole grains, cereals, nuts, seeds, soy and dairy

blood formation products, vitamin C and soaking beans, grains and seeds

enhances zinc absorption

Vitamin B12 Coenzyme required for normal metabolism of Dairy products, eggs, fortified soy milk and cereals

(cyanocobalamin) nerve tissue and of protein, fat and carbohydrate

Vitamin D Necessary for bone growth, promotes bone Dairy products, eggs, fortified soy milk and cereals

(cholecalciferol) mineralisation, aids in absorption of calcium and

maintaining nervous system, and normal heart action

Riboflavin Coenzyme involved in production of energy, stored Dairy products, soy milk, soy yogurt, soy cheese, fortified

in muscles and used during muscular fatigue breakfast cereals, grains and textured vegetable protein

Calcium Necessary for blood clott ing, nerve transmission, Dairy products, calcium-fortified soy milk, tofu, soy yogurt,

muscle stimulation, vitamin D metabolism, and cereals, low oxalate green vegetables such as broccoli, bok

maintaining bone structure choy and kale

that low iron stores increase the risk for iron defi- induced losses of zinc occur in urine and may re-

ciency anaemia and may adversely affect physical present up to 79% of dietary zinc that is absorbed.[62]

performance, especially aerobic activity.[14,18,27] Zinc losses may also be substantial for athletes who

exercise in hot, humid environments, although train-Vegetarian athletes can increase total iron intake

ing and environmental acclimatisation may decreaseby incorporating more leafy green vegetables such

these losses.[62] Zinc status may also influence exer-spinach, soy foods, legumes, dried beans, iron-forti-

cise-induced changes in zinc mobilisation, with thefied grains (such as fortified breakfast cereals), nuts,combined stresses of low zinc intake and maximalseeds and dried fruits (table II).[1,14,15,20,59,60] In addi-

exercise contributing to alterations in some bodytion, include fresh fruits, vegetables or juices rich in

zinc pools, as reflected by a reduction in circulatingvitamin C to enhance iron absorption.[61]

exchangeable zinc.[63] Zinc bioavailability also ap-

pears to contribute to zinc deficiency in vegetarians.6. ZincAs seen with iron, zinc absorption from plant foods

may be impaired by phytate, a potent zinc inhibi-Zinc is another nutrient of concern in a vegetarian

tor.[2,15,18,20,27] A food preparation technique vegeta-diet. Zinc is an essential trace mineral that is a

rian athletes may want to consider that enhancescomponent of >100 enzymes and is involved in

zinc absorption is soaking beans, grains and seedsimmune function, protein synthesis and blood for-

(table II).[1]mation.[15,18,27] Total zinc intake is generally lower

in vegetarian athletes than non-vegetarian ath-

letes.[15,18,20] The best sources of zinc are animal 7. Other Nutrientsproducts, meats and dairy products in particular,

which provide 50–70% of the zinc in an omnivore Vegetarian athletes may be at risk for low intakes

diet. In a vegetarian diet, zinc is found in legumes, of several other nutrients including vitamin B12,

whole grains, nuts, seeds, soy and dairy products vitamin D, riboflavin and calcium (table

(table II).[14,15,18,27] II).[1,14,15,18,19] The main sources for these nutrients

It may be difficult for a vegetarian athlete to are in animal products but can be found in many

maintain clinically normal plasma zinc concentra- alternative sources suitable for vegetarians. To help

tion because exercise, especially strenuous exercise, meet calcium needs, vegetarians, especially vegans,increases zinc loss from the body.[15,20,54] Exercise- should consider consuming calcium-fortified soy


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milk, tofu, soy yogurt, cereals and low oxalate green omnivores. For vitamin E, the enhanced antioxidant

vegetables such as broccoli, bok choy and kale. status was more consistently found when plasma or

Requirements for riboflavin can be met by consum- serum vitamin E was expressed in relation to serum

ing soy milk, soy yogurt, soy cheese, fortified break- cholesterol concentration. A higher vitamin E/cho-

fast cereals, grains and textured vegetable protein. lesterol ratio in vegetarians versus omnivores re-

Lacto-ovo-vegetarians can meet their vitamin B12 flects enhanced protection of LDL from oxidation.

needs by consuming dairy foods and eggs. Vegans In contrast with the antioxidant vitamins, vegetari-

should consume vitamin B12 fortified foods such as ans may have comparable or lower plasma or serum

fortified soy milk and fortified cereals. concentrations of the antioxidant minerals zinc, cop-

per and selenium, consistent with lower dietary

bioavailability of these micronutrients.[2] Burri[68]8. Antioxidantscommented that while lower than omnivores, dieta-

While findings among studies are not completely ry intakes of these antioxidant minerals is likely to

consistent, increased oxygen consumption and oxi- be adequate to support oxidative balance in cells.dative stress associated with higher intensity, longer Documentation of the antioxidant status of vegetari-

duration exercise is reported to increase production an and non-vegetarian athletes is lacking.[2,21,68]

of free radicals and other reactive oxygen species, It is unclear whether the use of antioxidant sup-and to promote lipid peroxidation.[20,64-67] The plements (in addition to dietary intake) can safelybody’s antioxidant defence system combats free and effectively help trained athletes reduce oxida-radical formation and relies on dietary intake of tive stress and increase performance, recovery timeantioxidant vitamins such as vitamins A (retinol), C and allow for more intense training.[64-66] Clarksonand E (tocopherol). However, it is still questionable and Thompson[64] concluded from their review of whether or not the body’s antioxidant defence sys- the available literature that antioxidant supplements

tem can keep up with increases in free radical pro- may or may not reduce exercise-induced oxidativeduction during exercise and whether additional anti- stress and does not lead to performance benefits.oxidant supplementation would be beneficial to ath- This supports the continuing controversy regardingletes.[20,64,66] Nieman[20] recommends that athletes whether athletes should consume antioxidant sup-who regularly perform intensive training should plements. No such controversy exists regarding theconsume diets rich in antioxidants. Vegetarians usu- benefits of ingesting an antioxidant-rich diet thatally consume large amounts of fruit, vegetables, and includes a variety of fruits, vegetables, whole grainswhole grains, nuts and seeds, which are rich in and other foods that are easily incorporated into aantioxidant nutrients and may reduce oxidative vegetarian diet.stress and risk for various diseases including heart

disease, cancer and arthritis.[2,4,6,18,20,65,67] Vegetarian9. Conclusionsdiets are also higher in phytochemicals that may be

potent antioxidants.[1,2,6,18,67] All athletes should carefully plan their diets to

Summarising dietary data from several studies, contain sufficient energy and nutrients to fully sup-

Rauma and Mykkanen[2] reported that vegetarians port their training and competition. There is suffi-

typically consume 500–1200g of fresh fruits and cient evidence to indicate that a well planned vege-

vegetables per day, have dietary intakes of vitamins tarian diet can meet the energy and macro- and

C and E and the pro-vitamin β-carotene above the micro-nutrient needs of an athlete and may reduceRDA, and have higher antioxidant status for vita- the risk for certain chronic diseases. Limited data

mins C and E, and β-carotene than omnivores. The from well controlled studies are available to supporthigher antioxidant statuses were reflected by higher or refute that consumption of a vegetarian diet influ-

serum or plasma concentrations of these vitamins ences athletic performance. At present, the majorityand pro-vitamin, respectively, in vegetarians versus opinion is that athletic performance is neither com-


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19. American College of Sports Medicine, American Dietetic Asso-Acknowledgementsciation, and Dietitians of Canada. Joint position statement:nutrition and athletic performance. Med Sci Sports Exerc

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2006 Vegetarian Diets- Nutritional Considerations for Athletes

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