If you consume a vegetarian diet and are physically active, there are nutritional guidelines to follow to ensure optimal health and exercise performance. As is with the non-vegetarian, energy requirements for the active vegetarian are dependent upon gender, age, body size, nutritional status, amount of activity involved in daily tasks, exercise mode, and intensity level, duration, and frequency of exercise. Due to the lower caloric density typically associated with the vegetarian diet, vegetarians, and particularly vegans, are at a greater risk for falling short of meeting daily energy needs. Taking in an insufficient amount of calories can result in loss of body weight below healthy levels and a loss of muscle mass resulting in decreased exercise performance. To meet your recommended daily caloric intake, you may need to include extra meals or snacks throughout the day.

The potential for consuming poor quality and inadequate amounts of protein are other concerns with the vegetarian diet. If all animal-based foods are avoided (e.g. milk), such as with the vegan, then there is the risk of consuming insufficient amounts of the amino acids lysine, methionine, threonine, and tryptophan. The physically active vegetarian should make it a point to consume a variety of plant-based protein foods to ensure a diet that is of sufficient protein quality. Such foods include whole grains, nuts, seeds, legumes, and soy products.

Plant-based proteins are not digested as well by the body as are animal-based proteins. As a result, the active vegetarian needs to increase the amount of protein consumed daily by about 10% beyond what is recommended for the non-vegetarian. This equates to an intake of about 1.2-1.8 grams/kilogram of body weight.

Physically active vegetarians are also at risk for consuming inadequate amounts of iron. In addition, your body is less efficient at extracting iron from plant sources than it is from animal sources. This increases the likelihood of developing iron deficiency or anemia, particularly for the physically active female. In general, iron stores of vegetarians are lower than those of non-vegetarians. Good sources of iron include soy beans (1/2 cup cooked provides 4.4 mg), tofu (firm, 1/2 cup provides 6.6 mg), lentils (1/2 cup cooked provides 3.3 mg), pumpkin seeds (1/4 cup provides 5.2 mg), and fortified cereal (1 oz. provides 5.1 mg). Since Vitamin C can enhance absorption of iron, it is recommended that you consume it at the same time as you do the iron source.

If you follow a diet that eliminates all animal protein or one that is very low in fat (<15% of total energy intake) you are at risk for developing a deficiency of essential fatty acids. Fatty acids are an important fuel source for moderate-intensity aerobic exercise. In addition, as you become more aerobically fit, your body uses a greater percentage of fat to perform the activity while decreasing the use of carbohydrate sources.

Other nutrients that physically active vegetarians may consume insufficient amounts of include Vitamins D, B12, and riboflavin and minerals zinc and calcium. To ensure that you are consuming an adequate amount of calories as well as required nutrients you may want to consider consulting a sports dietitian. This is of particular importance if you are a novice vegetarian or have been a previously sedentary vegetarian engaging in exercise for the first time.

Note: Before beginning an exercise program or increasing the intensity level of a current routine, a physician's approval should be obtained, especially for older adults and those at risk for or who currently have chronic health conditions.

Resources:

American College of Sports Medicine, American Dietetic Association, and Dietitians of Canada Joint Position Statement "Nutrition and Athletic Performance", Medicine & Science in Sports & Exercise, pp. 709-731.

President's Council on Physical Fitness and Sports Research Digest Series 5, No. 1; March 2004 (www.fitness.gov)

Journal of the American Dietetic Association, June 2003, Vol. 103, No. 6; pp. 748-765, "ADA Reports: Position of the American Dietetic Association and Dietetics of Canada: Vegetarian Diets." (www.eatright.org)

Vegetarian Nutrition: A Dietetic Practice Group of the American Dietetic Association, "Vegetarian Diet for Exercise and Athletic Training and Performing: An Update", Larson, D.E.