Over the decades, authorities have published public dietary and nutritional guidelines in an attempt to inform individuals about the healthiest choices to optimize health and prevent disease. However, conflicting and sometimes contradictory messaging has often led to more confusion than clarity. With so many different types of diets and supplements available it is difficult to know if they are really right for you. We have all heard some people say that certain diets work wonders for them but unfortunately not all see the same success. Part of the reason there are wide variations in individual responses to different diets and
Athletes have special needs when it comes to fuelling for optimized performance. Nutrition requirements are continuously shifting depending on the desired activity as well personal goals such as weight loss or improvements to lean muscle mass. There are a growing number of vegetarian athletes at the amateur and professional levels which raises discussions on whether or not an athlete is put at a disadvantage when choosing to eliminate some or a majority of animal derived foods. While there are several types of different vegetarian diets, including but not limited to lacto-, ovo- and macro-, we are going to discuss the general trends that are seen within vegetarian diets and their impact, or lack thereof on sport performance.
The major areas that vegetarians are perceived to be at a disadvantage are with regards to protein quality, creatine stores and iron bioavailability. As long as vegetarian athletes understand these potential blind spots, strategies can be put in place to ensure what is not consumed in diet is added to their targeted supplement regimen. This might also require some changes to nutrient timing to ensure that nutrients, such as iron, are given the best chance to be absorbed and utilized.
Protein intake is critical to the exercise recovery process. The amino acids from protein are important building blocks that make sure muscle repair and adaptation are maintained. Protein is also important for promoting healthy aging and improving appetite regulation (Phillips, Chevalier, & Leidy, 2016). How much protein do we need? Protein needs can increase when moving from endurance to strength based exercises, the research indicates that athletes should look to maintain intake of at least 1.2 g/kg bodyweight per day for endurance specific sports with some studies examining strength and power sports showing benefit at 1.6-2.4g/kg bodyweight per day (Jager, et al., 2017).
Does protein source matter?
Vegetarian specific proteins have less diversity when it comes to amino acid content compared to animal sources so this means sometimes you have to consume more to guarantee you reach the right amount and diversity of amino acids for success. To support a balanced protein intake, vegetarians are encouraged to consume many different types of proteins (i.e., soy, rice, hemp, pea, pumpkin etc.) to have a well-rounded consumption of essential amino acids (Joy, et al., 2013). One amino acid in particular, leucine, is most important for stimulating muscle protein synthesis (Katsanos, et al. 2006). Leucine is not as concentrated in vegetarian protein sources and as such, vegetarian athletes need to make sure their intake equals 2-3 grams of leucine per protein serving, to maximize muscle repair. This is as easy as consuming 2-2.5 cups of lentils. One interesting study also looked at whey vs soy proteins to answer the question of whether or not levels of testosterone and estrogen changed and its effect on resistance training (Kalman, et al. 2007). It was found that 25 g of soy protein taken within one hour after training had no significant changes to testosterone or estrogen levels compared to a blend of whey concentrate and isolate. This challenges the notion that soy isoflavones might alter exercise adaptation via sex hormone modulation in resistance trained athletes. It would be interesting to see this study followed up with longer duration, additional subjects, and more stringent dietary controls.
Take home message: protein source does not matter as long as you are getting the right amount, quality and diversity of protein. Leucine is critical and if you are not able to reach the necessary amount of leucine per serving of protein than vegetarian athletes are encouraged to add a branch chain amino acid or leucine supplement for adequate maintenance of skeletal muscle mass.
Well-designed vegetarian diets are diverse in fibre, healthy fats, macro and micro nutrient intake but there are some nutrients that are difficult to maintain. Iron and vitamin B12 in particular can be hard to source for many vegetarians (Barr & Rideout, 2004). Both iron and vitamin B12 are important to maintaining the body’s iron stores to prevent anaemia. In sport, especially endurance athletes, anemia results in reduced muscle enzyme activity as well as lowered oxygen and carbon dioxide transportation. As a result, athletes will have reduced performance or early plateau with increased fatigue, weakness, and potentially dizziness during activity (Chartard, et al. 1999). Iron and vitamin B12 are difficult to absorb from vegetarian sources. Non-animal sources of iron such as leafy greens, cereals, breads etc. typically have marked reduction in intake due to the presence of calcium, phytate, and bran. Vitamin B12, is a critical part to iron metabolism , along with copper, so vegetarians must make sure they have consistent intake. As athletes can lose iron from training, sweating, bleeding, and menstruation this is an area vegetarian athletes are advised to seek out lab testing to make sure their needs are being met.
Omega 3 fatty acids are important for cardiovascular health, management of the inflammatory response and are also thought to improve heart-rate variability (Rogerson, 2017). Omega 3s from vegetarian sources are typically limited to algea or must be manufactured by the body through the conversion of alpha-linolenic acid to EPA and DHA. Unfortunately not eveyrone is efficient at this conversion raising the need for additional supplementation. Still, there is rational for improving the amount of flax, hemp, chia, and walnuts to optimize intake of alpha-linolenic acid on top of a vegetarian sourced omega 3 fatty acids.
Vegetarian diets are naturally low in creatine, one of the most important ergogenic aids to performance. Sourced from meat, fish and poultry, creatine improves short-term high intensity exercise, strength and muscle growth. Supplementation of 3-5 g per day for four weeks of creatine monohydrate in vegetarian athletes show improvements to fat free mass and functional muscle changes compared to omnivores (Rogerson, 2017). There are a lot of myths regarding the safety of creatine but it is still considered to be generally safe, well tolerated by most, and available in synthetic non-animal sourced forms.
Vegetarian athletes are as capable of succeeding as any other athlete provided their diet and supplement regimen is finely tuned. Poorly constructed vegetarian diets will leave athletes at a disadvantage so it is important that these athletes ensure their protein intake is optimal along with attention to their individual needs for nutrients such as iron, vitamin B12, and omega 3 fatty acids as well as ergogenic aids such as creatine.
Barr, S. I., & Rideout, C. A. (2004). Nutritional Considerations for Vegetarian Athletes. Nutrition, 696-703.
Chartard, J.-C., Mujika, I., Guy, C., & Lacour, J.-R. (1999). Anaemia and iron Deficiency in athletes. Sports Medicine, 229-240.
Jager, R., Kerksick, C. M., Campbell, B. I., Cribb, P. J., Skwiat, T. M., Purpura, M., et al. (2017). International Society of Sport Nutrition Position Stand: Protein and Exercise. Journal of the International Society of Sports Nutrition, 14(20).
Joy, J. M., Lowery, R. P., Wilson, J. M., Purpura, M., De Souza, E. O., Wilson, S. M., et al. (2013, June 20). Effects of 8 weeks of whey or rice protein supplementation on body composition and exercise performance. Nutrition Journal, 12(1), 86-92.
Kalman, D., Feldman, S., Martinez, M., Krieger, D. R., & Tallon, M. J. (2007). Effect of protein source and resistance training on body compositition and sex hormones. Journal of the International Society of Sports Nutrition, 1-8.
Katsanos, C., Kobayashi, H., Sheffield-Moore, M., Aarsland, A., & Wolfe, R. (2006, Feb 28). A high proportion of leucine is required for optimal stimulation of the rate of muscle protein synthesis by essential amino acids in the elderly. American journal of physiology. Endocrinology and metabolism., 291(2), 381-387.
Phillips, S. M., Chevalier, S., & Leidy, H. J. (2016). Protein “requirements’ beyond the RDA: implications for optimizing health. Applied Physiology, Nutrition and Metabolism, 41(5), 565-572.
Rogerson, D. (2017). Vegan Diets: Practical advice for athletes and exercisers. Journal of the International Society of Sprots Nutrition, 1-15.