January 2009 Issue
Plant Power: Fueling Athletes Right Through Balanced Vegetarian Nutrition
By Pamela M. Nisevich, MS, RD, LD
Vol. 11 No. 1 P. 38
Sans animal proteins, can competitors who follow a vegetarian diet meet their energy and achieve optimal performance?
This past October, the changing leaves signaled the arrival of fall racing season. For me, that meant another go at the Chicago Marathon. Those who participated in the previous year’s event surely remember what happened: Soaring temperatures forced race officials to close down the course as many runners suffered from heat stroke, confusion, and dehydration.
This year was different. As I approached the starting line, the temperature was bearable, and the alert system, which served to notify runners of course conditions, was in place. But something besides the weather lingered on my mind: my diet. No, I wasn’t worried about my carb-loading efforts or my hydration status. I was concerned about the fact that I had been following a vegetarian diet throughout the last months of my training regimen. Would the diet prove disastrous or beneficial? Would I achieve my racing potential while following this diet?
Traditional studies of short-term vegetarian diets, in which athletes consumed a vegetarian diet for a period of two to six weeks, have detected no changes in performance based on the absence of animal products in the diet.1,2 Older observational studies of vegetarian vs. nonvegetarian athletes have not found differences in performance of fitness associated with the amount of animal protein consumed.3,4 These findings hold true under the assumption that a vegetarian diet is balanced, varied, and adequate. But what about current studies and recommendations?
During the conversion process from omnivore to herbivore, I struggled with lethargy, weight loss, and general malaise. Despite the fact that I am a trained dietitian and an athlete, I had much to learn about this new pattern of eating. I began to empathize with many vegetarian and vegan athletes who suffer from nutrient deficiencies. When I was hungry and tired or searching for a preworkout snack, I couldn’t rejuvenate with my usual turkey sandwich or a chicken Caesar salad, and I couldn’t recover with meat lover’s pizza or chicken noodle soup. Instead, I needed to find alternate sources of energy, protein, and nutrients because, as sports dietitians and athletes know, performance is directly linked to nutrition.
Macronutrient Needs of Vegetarian Athletes
All athletes have energy to burn, so vegetarian athletes aren’t any different. Just as athletes vary widely, so do their energy needs, which depend on body size, body composition, training regimen, and sport type and intensity.5 When vegetarian diets are well balanced and provide ample energy, they are capable of providing enough energy to prevent catabolism and premature fatigue. However, many vegetarian athletes, myself included, often find it difficult to consume enough healthy vegetarian food items to meet energy needs. Vegan athletes in particular may find it challenging to meet energy needs for training and competition.
As I struggled with my vegetarian diet experiment and worried about how it would impact my marathon performance, I sought advice from D. Enette Larson-Meyer, PhD, RD, author of Vegetarian Sports Nutrition. Larson-Meyer reminded me to keep my energy and nutrient intake high—and she was right. Following her advice, I calculated the calorie and protein needs of an endurance athlete, and soon I was back on track.
How can dietitians help vegetarian athletes perform their best while keeping their energy levels high? Specific recommendations include supplementing the diet with high-energy foods such as nuts, heart-healthy oils, dried fruit, and other nutrient-dense items. Athletes should also consume small, frequent, nutrient-dense meals throughout the day and monitor their protein intake. In general, vegetarian athletes’ diets are naturally high in carbohydrate, and protein intake should be closely monitored. Fat intake should comply with the Acceptable Macronutrient Distribution Range of 20% to 35% of total calories from fat and should come from heart-healthy, unsaturated sources such as plant oils.
Athletes’ protein needs are likely higher than those of most other people. Vegetarian and vegan athletes, as well as those concerned with caloric intake and weight, need to pay close attention to their protein choices and serving sizes. When comparing protein intakes among vegans, lacto-ovo vegetarians, and omnivores, Messina and Messina found that the intakes of energy from protein ranged from 10% to 12%, 12% to 14%, and 14% to 18%, respectively.6
Why is protein important for an athlete? It is involved in numerous physiologic processes, including maintaining acid-base balance, supporting the immune system, building lean muscle, and maintaining nitrogen balance. During exercise and at rest, the body tries to conserve protein and therefore does not typically rely on it as a fuel source. In properly fed individuals, protein provides for less than 5% of energy expended.
While researchers have thoroughly studied athletes’ protein needs, the debate about whether physically active individuals require more protein than their sedentary counterparts continues. Ask any athlete and his or her answer to this debate is yes, athletes require more protein. Indeed, experience often tells athletes that higher protein diets are beneficial and perhaps necessary.7 While the controversy continues, according to the most recent position statement by the American Dietetic Association (ADA), Dietitians of Canada (DC), and the American College of Sports Medicine (ACSM), the likely reasons behind increased protein needs for athletes are due to exercise-induced muscle breakdown and the consequent need for rebuilding, the use of small amounts of protein for energy, and the need for additional protein to support gains in lean muscle mass.
Recommended Protein Intake
The recommended daily allowance (RDA) for protein for the general adult population is 0.8 grams per kilogram per day. Protein recommendations for endurance athletes range from 1.2 to 1.4 grams per kilogram per day. During times of intense training, including resistance exercise, this recommendation increases to 1.6 to 1.7 grams per kilogram per day.
Most athletes do not experience difficulty when trying to achieve recommended intakes. In lacto-ovo vegetarians and vegans consuming adequate amounts of plant and vegetable proteins, severe protein deficiency is uncommon. In fact, a vegetarian diet can supply all essential and nonessential amino acids from plant foods alone if a variety of these foods is consumed over the course of the day and with adequate amounts of energy. However, vegan athletes should pay close attention to their protein intake and may benefit from the use of protein supplements and nutritional shakes to meet needs. In general, a modest 10% increase of protein intake over the acceptable macronutrient distribution range of 10% to 35% may be beneficial to vegetarian athletes. This increase is recommended to adjust for the incomplete digestion of plant proteins.
Overall, if they maintain a healthy body weight and follow sound nutrition practices, few athletes are at risk for protein malnutrition.
Plant-based diets are considerably higher in carbohydrate than traditional diets that include animal products. Messina and Messina report that among the general public, the carbohydrate intake of vegans and lacto-ovo vegetarians ranged from 50% to 65% and 50% to 55% of total energy intake, respectively.6 Nonvegetarians consumed less than 50% of total energy from carbohydrate.
It is easy to see why many athletes follow a vegetarian diet: to boost carbohydrate content. Carbohydrate is the primary fuel for physical activity, and athletes need adequate stores for optimal performance. Carbohydrate is stored in muscles and the liver in the form of glycogen. In most athletes, the amount that can be stored ranges from approximately 375 to 500 grams, depending on training intensity and dietary intake. Since stores are limited, carbohydrate must be consumed daily and before a workout, during longer workouts and events, and after exercise. An athlete’s carbohydrate requirements depend on whether he or she is interested in endurance activities or weight-resistance activities.
The following carbohydrate intake ranges are for athletes of all shapes and sizes. In general, smaller athletes should consume carbohydrate at the low end of the range, while larger athletes or those looking to gain weight should consider selecting from the higher end of the range.
Recommended Carbohydrate Intake
The amount of carbohydrate an athlete needs ranges from 5 to 10 grams per kilogram per day. This range can be further broken down based on training level and event. Burke et al suggest that athletes in general training consume 5 to 7 grams per kilogram of carbohydrate per day and endurance athletes consume 7 to 10 grams per kilogram per day.8
What About Supplements?
Creatine has gained popularity over the years as a performance-boosting supplement. Approximately 95% of the total body pool of creatine is located in skeletal muscle, where it exists as creatine phosphate and free creatine. Creatine phosphate, which accounts for two thirds of the total creatine in muscle, is the storage form of creatine and serves as an energy source during exercise. According to Venderley and Campbell, creatine phosphate is broken down during exercise to creatine and phosphate by creatine kinase.5 Phosphate rapidly combines with adenosine diphosphate to form adenosine triphosphate (ATP). This rapid resynthesis of ATP during exercise helps provide a steady stream of energy for muscle contraction. As creatine phosphate concentration declines during maximal exercise and its depletion contributes to muscle fatigue, many athletes consider supplementing with creatine to increase muscle stores.
Burke and colleagues report that baseline muscle creatine stores are lower in vegetarian athletes (lacto-ovo and vegan) than in nonvegetarian athletes.9 They also suggest that ingesting creatine monohydrate may augment an athlete’s adaptations to resistance training by facilitating changes in lean muscle mass and increasing muscle fiber area, muscle strength, and resistance to fatigue. In a study that sought to compare the changes in muscle creatine, muscle fibers, body composition, hydration status, and exercise performance in vegetarian and nonvegetarian athletes treated with eight weeks of creatine supplementation and weight resistance training, Burke and colleagues found that while there were no significant differences between vegetarian and nonvegetarian athletes in terms of baseline phosphocreatine or ATP concentrations, there were differences in total creatine concentration.9 The study also found that the ingestion of creatine by vegetarians has a greater impact in terms of total creatine concentration, phosphocreatine, lean tissue, and total work performance.9
These findings are supported by the findings of Lukaszuk et al, who demonstrated that a 26-day trial lacto-ovo vegetarian diet led to reduced muscle creatine content in omnivorous individuals.10 When these individuals took a creatine supplement, the result was an increase (though not statistically significant) in total creatine concentration vs. the placebo group. While much research is needed before recommending creatine supplementation to all vegetarian athletes, the research findings by these researchers and others deserve consideration and discussion.
What About Deficiencies?
According to the ADA, the DC, and the ACSM’s position statement, vitamins and minerals play vital roles in energy production, growth and development, and the maintenance and protection of bones, tissues, organs, blood, and the immune system. For most athletes with adequate energy intakes, the RDA or Dietary Reference Intake (DRI) suffices. Athletes who excessively lose micronutrients in their urine, sweat, and feces may require supplementation, and vegetarian and vegan athletes who have eliminated food groups from the diet may also require supplementation.
Common micronutrients that should be closely monitored and possibly supplemented include vitamin D, riboflavin, calcium, vitamin B12, iron, and zinc. Deficiencies are most common in female athletes and can have dire consequences: low bone density and stress fracture risk (calcium deficiency), poor performance and fatigue due to depleted hemoglobin and hematocrit (iron deficiency), and negatively impacted muscle growth, development, and repair, as well as fatigue (zinc deficiency). Ensuring adequate intake of all B vitamins, especially B12 and folate, is vital. By consuming a diet rich in whole grains, fortified foods, and complete proteins, athletes can greatly reduce their risk for vitamin and other deficiencies.
Iron is critical to athletic performance, as it is used in the synthesis of hemoglobin and myoglobin, essential components involved in transporting and delivering oxygen to working muscles. Vegetarian and vegan diets often contain as much if not more iron than conventional diets. Concerns about vegetarian and vegan athletes’ iron status usually surround the bioavailability of nonheme iron from plant sources. To increase the absorption of nonheme iron, The Vegetarian Resource Group suggests consuming foods containing vitamin C, along with foods containing iron, and states that “dried beans and dark green leafy vegetables are especially good sources of iron, even better on a per-calorie basis than meat.” In addition to these food items, spinach, soy, legumes, dried beans, nuts, seeds, and iron-fortified grains should also be mainstays in the vegetarian athlete’s diet.
Vegetarians who exclude all foods from animal sources do not have a natural source of the essential vitamin B12. Although recommendations for vitamin B12 are low (the DRI for adults is 2.4 micrograms per day), a vitamin B12 deficiency is very serious and can lead to nerve damage and macrocytic anemia. Vegans can meet needs by consuming fortified foods or a supplement.
Zinc plays a role in myriad body functions, including immune function, protein synthesis, and blood formation. Because up to 79% of absorbed zinc can be lost in the urine following strenuous exercise, and athletes exercising in hot, humid environments lose more zinc than their cooler climate competitors, all athletes must ensure that their dietary intake of zinc is adequate.11 While the best sources of zinc are animal products—meat and dairy in particular—vegetarians can meet their needs for zinc (8 milligrams per day for adult women and 11 milligrams per day for adult men) by including legumes, whole grains, nuts, seeds, and soy in their diet.
What About Performance?
If you think Hank Aaron, Billie Jean King, and Joe Namath don’t have anything in common, you’re mistaken. These famous athletes, along with various other Olympians, professionals, and thousands of elite athletes, followed a vegetarian diet at some point in their career. According to his review of literature pertaining to athletic performance and vegetarian diets, Nieman concluded that “…a vegetarian diet is neither beneficial nor detrimental to cardiorespiratory endurance, especially when carbohydrate intake, age, training status, body weight, and other confounders are controlled for.”12 Other studies reviewing the impact of vegetarian and vegan diets on performance concur with Nieman’s findings.
Even though I was not a big meat eater, as soon as I eliminated it from my diet, I began to feel the effects. Whether they were physical or psychological, I couldn’t say. But because all I could think about was meat, I struggled with crafting a meal plan to supply enough macronutrients and micronutrients to fuel my workouts. Initially, my workouts were sluggish, and I couldn’t perform at the level to which I was accustomed. But once I began to carefully monitor my energy intake, religiously take a multivitamin, and experiment with combination foods, my performance began to improve.
As I toed the line at this past fall’s Chicago Marathon, I felt prepared. I was armed with vegetarian-approved gels, hydrated with vegan-approved sports drinks, and had trained extensively. While I easily surpassed my previous, heat-inflicted Chicago Marathon time, this year’s finish was only seconds off my spring personal best. Apparently, the experts were right when they found that vegetarian diets are neither beneficial nor detrimental to performance when followed properly.
— Pamela M. Nisevich, MS, RD, LD, is an author and a speaker with Nutrition for the Long Run in Dayton, Ohio. She is a sports dietitian and an avid marathoner.
Sports Nutrition Supplements for Vegetarian Athletes
Many sports nutrition products on the market are appropriate for vegetarian and vegan athletes. Because these items are high in carbohydrate and devoid of protein, they are typically free of animal products. But if the preworkout bars contain chocolate flavoring, it’s likely they include milk chocolate—an ingredient vegan athletes avoid.
Gels, chews, and beans are usually void of protein, and certain fruit flavors are vegan approved. Recovery bars and shakes often contain whey protein, which vegan athletes avoid. However, some recovery bars, such as the CLIF Bar Builder’s bars, are made with soy protein and nuts and are appropriate for both vegetarian and vegan athletes.
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