Some athletes choose to follow vegetarian diets. Nutrition recommendations for these athletes should be formulated with consideration of the effects of both vegetarianism and exercise. The position of the American Dietetic Association on vegetarian diets (147) provides appropriate dietary guidance that should be considered in conjunction with the information provided herein.
Vegetarianism does not necessarily affect energy needs, though energy availability could be reduced slightly if a vegetarian has an extremely high fiber intake. As with all athletes, monitoring body weight and composition is the preferred means of determining if energy needs are satisfied. Some people‹especially women‹may switch to vegetarianism as a means of restricting energy intake to attain the lean body habitus favored in some sports. Occasionally, this may be a step toward development of an eating disorder (148). Because of this association, coaches and trainers should be alert when an athlete becomes vegetarian, and ensure that appropriate weight is maintained.
Studies consistently report that vegetarians have lower protein intakes than omnivores. Although the protein quality of a vegetarian diet is adequate for adults (2,51,149), plant proteins are not as well-digested as animal proteins (2). Thus, to adjust for incomplete digestion, an increase of about 10% in the amount consumed may be made (2). Accordingly, recommended protein intakes for vegetarian athletes would be about 1.3 to 1.8 g/kg body weight, using recommendations for athletes as a baseline (53,54,57). Vegetarian athletes with relatively low energy intakes may need to choose foods carefully to ensure that their protein intakes are consistent with these recommendations.
Vegetarian athletes may be at risk for low intakes of vitamins B-12 and D, riboflavin, iron, calcium, and zinc, because many of these nutrients are high in animal products. Iron is a nutrient that may be of particular concern to vegetarian athletes. Because of the lower bioavailability of iron in plant-based diets, the iron stores in vegetarians are generally lower than those of omnivores, despite total iron intakes that are similar or even higher (150). When combined with data indicating that exercise may increase iron requirements, it is possible that vegetarian athletes, especially women, may be at greater risk of developing poor iron status. Accordingly, it would be prudent for iron status to be monitored routinely in female vegetarian athletes.
