Plant-based diets are increasing in popularity amongst the general population which has sparked interest within the athletic community. This may be due to potential performance and health benefits, as well as environmental sustainability efforts. Let’s first make the distinction between mostly plant-based and popular diets such as vegan and vegetarian. Consuming a mostly plant-based diet does not eliminate animal products and may even incorporate more plant-based foods to substitute the frequency of consumption of animal-based foods. Meanwhile, vegan and vegetarian diets are amongst the more extreme forms of dietary restriction (West et al., 2023). A vegetarian diet does not include any foods made from animal meat or animal by-products, while a vegan diet does not include any foods that can be sourced back to an animal, including dairy and eggs.
Reasons why athletes may choose to follow a plant-based diet may include:
Perceived health benefits
Ethical beliefs
Environmental concerns
Social factors
Sensory preferences
The more you know…
Whatever an athlete’s reasoning is, they should be made aware of the unique nutritional challenges this strategy may present. Possible direct consequences of following a plant-based diet may include: suboptimal daily energy intake, poor protein quality, as well as, risk of essential micronutrient deficiencies. Keep in mind, that it is possible for an athlete to meet their nutritional needs even while on a restrictive diet. However, it requires a solid foundation in nutrition education, careful food selection, meal planning, access, and even regular consultation with a healthcare provider.
Before we move on, let’s define some key terms to help better understand:
Deficiency- refers to the minimum amount of that nutrient required to support basic function or health within the general population
Suboptimal- within sports, this refers to nutrient intake at a certain level to maximize a given parameter related to athletic goals.
Ab libitum- means to occur or be used as often as desired
RDI- recommended daily intake
More energy, more energy!
One of the primary challenges faced by plant-based athletes is suboptimal energy intake. Plant-based foods tend to be less calorie-dense compared to animal-based foods, which can make it challenging for athletes to consume an adequate number of calories to meet their daily energy needs. In West et al., 2023, table 2 lists several studies that show, within the general population, those who follow a vegan diet consume less energy than those on an omnivore diet. With careful consideration of serving sizes and meal frequency, high-performance athletes can maintain optimal energy balance while on a plant-based diet.
Additionally, plant-based diets are often high in fiber and water content, which can increase satiety [feeling of fullness] and influence natural hunger cues, making it difficult for athletes to eat enough to fuel their bodies properly. Particularly with ultra-endurance athletes, consuming enough calories can be difficult to achieve and challenging on the gut when fiber intake is excessively high. Consider a cyclist participating in the Grand tour. These athletes can need up to 6,000-8,000 calories per day!
Plant-based athletes who struggle to consume enough calories each day may choose to consume only ⅓- ½ of their grains and fruits in whole, unprocessed form to reduce excessive fiber intake and limit the early onset of fullness (Rosenbloom, 2017). Additionally, they can choose more energy-dense foods such as nuts, seeds, oils, and avocados. These higher-fat foods have more calories per serving without too much gastrointestinal stress.
I’m whey into you meeting your protein goals
In addition to energy intake, plant-based athletes need to pay attention to their macronutrient intake; particularly, protein quantity and quality. While it is possible to obtain an adequate amount of protein from plant-based sources, these sources contain a lower proportion of total protein (West et al., 2023). This would then require a larger serving of protein to be consumed to still achieve an athlete's RDI.
In terms of quality, this includes a “... protein source’s amino acid composition, digestibility, and subsequent bioavailability of (specific) amino acids, and the metabolic fate of those amino acids” (West et al., 2023). Animal proteins contain a complete amino acid profile [meaning, all 9 essential amino acids or EAA are present] and specifically, dairy, egg, and meat-derived products have a very high EAA content which has been shown to correlate to the magnitude of post-exercise muscle protein synthesis or MPS response. MPS is what helps an athlete recover and build muscle after exercise. Soy protein and most legumes are a rich source of leucine for plant-based athletes. However, there is still debate on whether or not these athletes should consume somewhere around 10% more protein than omnivores to account for lower digestibility (Rosenbloom, 2017).
In the past, protein complementing has been suggested to optimize the efficiency of potential suboptimal protein sources. Protein complementing includes strategically combining plant proteins in the same meal to improve EAA content (Rosenbloom, 2017). For instance, grains are typically low in lysine but high in methionine, whereas beans, lentils, and peas are low in methionine and high in lysine. Although, if an athlete is consuming a variety of plant proteins, especially beans and soy products, they may not need to be too concerned about protein complementing each and every meal (Rosenbloom, 2017).
Don’t forget the little guys…
Lastly, plant-based athletes are also at risk of micronutrient deficiencies, as certain nutrients that are abundant in animal products may be lacking in plant-based diets. Some common micronutrients at risk of deficiencies if ab libitum include:
Vitamin D: Plant-based sources of vitamin D are limited, and athletes who do not get enough sunlight exposure may be at risk of deficiency. Supplementation or consuming vitamin D fortified foods may be necessary to meet vitamin D requirements.
Creatine: Creatine is naturally found in animal products and plays a crucial role in energy metabolism during high-intensity exercise. Plant-based, female, and older athletes may benefit from creatine supplementation to enhance performance.
Iron: Iron depletion is the most prevalent nutrient deficiency, especially in female athletes (Rosenbloom, 2017). Plant-based sources of iron (non-heme) are less bioavailable compared to heme iron found in animal products. Plant-based athletes should consume iron-rich plant foods such as legumes, leafy greens, and fortified cereals to prevent iron deficiency. Additionally, to enhance iron absorption athletes can pair iron-rich foods with vitamin C or any other organic acids (citric, malic, lactic, and tartaric acids) containing foods.
Vitamin B12: Vitamin B12 is primarily found in animal products and plays a crucial role in red blood cell formation and nerve function. Plant-based athletes are advised to take B12 supplements or consume fortified foods to avoid deficiency.
Other nutrients to monitor: Zinc, iodine, magnesium, carnosine, and carnitine.
In conclusion, while plant-based diets may offer numerous health benefits, athletes need to be mindful of the unique nutritional challenges they may face. By paying attention to energy intake, macronutrient quality and quantity, and micronutrient deficiencies, plant-based athletes can optimize their diets to support their athletic performance and overall health. Consulting with a healthcare provider or registered dietitian can help athletes develop a nutrition plan tailored to their individual needs and goals.
References
Rosenbloom, C. (2017). Sports Nutrition: A Handbook for Professionals (C. Karpinski, Ed.; 6th ed.). American Dietetic Association.
West, S., Monteyne, A. J., van der Heijden, I., Stephens, F. B., & Wall, B. T. (2023). Nutritional considerations for the vegan athlete. Advances in Nutrition (Bethesda, Md.), 14(4), 774–795. https://doi.org/10.1016/j.advnut.2023.04.012
Wilson, P. (2020). The athlete’s gut: The inside science of digestion, nutrition, and stomach distress. VeloPress.
About the Author
Jourdan Delacruz is a 2X Olympian and represented Team USA in the sport of Weightlifting for both the 2020 and 2024 Olympic Games. Jourdan holds a bachelor's in nutrition and dietetics from the University of Northern Colorado. She is pursuing her master's degree in sports nutrition with hopes of becoming a sport-registered dietitian. Jourdan is the founder of Herathlete, a brand committed to supporting female athletes through education and community.
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