Many individuals are opting to reduce their consumption of meat and animal products due to various reasons such as health, personal beliefs, or athletic performance. However, transitioning to a plant-based diet requires an understanding of the nutritional considerations involved. This article delves into the advantages and disadvantages of embracing a vegan or vegetarian diet as an athlete and provides practical guidance on obtaining essential nutrients to enhance performance.

Defining Plant-Based

The term plant-based in dietary contexts generally equates to vegan, representing a diet entirely devoid of animal products.¹ Vegans abstain from consuming meats, eggs, dairy, and other animal-derived products like honey. Vegan diets also shun additives sourced from animals such as gelatin, casein, and lactose.²

Vegetarian or semi-vegetarian diets exclude meat but may include some dairy, fish, eggs, or foods containing animal byproducts.² While not precisely categorized as fully plant-based, these diets still reduce animal protein intake and share similar nutritional implications. Hence, while this post primarily targets vegan athletes, its advice can benefit any athlete aiming to cut down on animal-derived foods.

An Emerging Trend

From casual enthusiasts to top-tier competitors, a small but rising number of cyclists and triathletes are transitioning from omnivorous diets to plant-based diets³. This shift mirrors broader trends beyond sports, with a surge in the popularity of meatless or reduced-meat diets noted in numerous countries. Plant-based meat, milk, and egg substitute sales in the US soared by 43% in the past two years⁴, and the global vegan food market is projected to increase by 9.6% annually until 2025⁵. While survey results differ⁶, around 6% of the US population and 10% of Europeans self-identify as vegetarian or vegan⁷, with data suggesting even higher numbers among endurance athletes⁸.

The Potential Advantages of a Plant-Based Diet

For many vegans and vegetarians, animal welfare and ecological concerns drive the reduction in animal product consumption⁹. However, the focus here is on how a plant-based diet can influence health and athletic performance, with numerous studies indicating significant benefits.

Studies and reviews consistently demonstrate a correlation between reduced meat consumption and lower average body mass indexes (BMIs). Vegetarians generally exhibit lower BMIs than meat-eaters, with vegans displaying the lowest average BMIs¹⁰. While BMI has its limitations, it serves as a useful measure for assessing weight status and related health risks on a population scale¹¹. This suggests that plant-based diets may lessen the likelihood of weight-related conditions, a notion supported by studies showing reduced risk of heart disease-related mortality, decreased hypertension risk, and lower cholesterol and blood sugar levels in individuals adhering to vegan diets compared to omnivorous diets¹².

Furthermore, individuals on vegan diets demonstrate a reduced risk of certain cancers and an overall enhanced life expectancy¹³. Whether attributed to the absence of animal products or the incorporation of beneficial components like whole grains, fruits, and fresh vegetables common in plant-based diets remains unclear. Vegan diets typically provide elevated amounts of fiber, antioxidants, and vitamins compared to standard omnivorous diets¹⁴.

Healthy athletes are more robust athletes. While the direct impact of plant-based diets on athletic performance is uncertain, balanced vegan and vegetarian diets are deemed suitable for fulfilling the nutritional requirements of competitive athletes⁸. The success of elite competitors in various sports validates this assertion.

Potential Challenges of a Plant-Based Diet

While evidence indicates the health benefits of plant-based diets, it is imperative to recognize that not all plant-based diets are equally nutritious. Transitioning from an omnivorous to a plant-based diet does not automatically equate to enhanced nutrition. While plant-based diets generally contain lower levels of sugar, salt, and saturated fats than typical Western diets¹⁴, the proliferation of high-calorie processed vegan alternatives poses a risk. It is feasible to consume a diet rich in fat, sugar, and lacking nutritional quality in a plant-based format, potentially negating the health benefits linked to a plant-based lifestyle.

Plant-based diets may lack crucial nutrients commonly found in animal-derived products. Although the risk may not be as severe as commonly perceived⁸, health authorities affirm the capacity of vegan diets to provide balanced and sufficient nutrition¹⁵. Variety is key—a wholesome plant-based diet inclusive of an array of vegetables, fruits, legumes, and grains is likely to offer adequate nutrition. Conversely, a careless and restricted vegan diet might fall short. Let’s explore common nutritional deficiencies associated with plant-based diets for athletes and consider possible solutions.

Calories

The primary objective of any diet is to provide sufficient energy (measured in calories) for bodily functions. Given that plant-based foods are generally less calorie-dense compared to animal-inclusive foods¹⁶, some vegans may struggle to consume adequate calories for endurance sports demands, especially if their diet emphasizes vegetables and whole foods, prevalent in most plant-based diets.

A slight caloric deficit can aid weight loss or body composition improvement. However, most athletes can compensate by increasing overall food intake and incorporating calorie-rich whole foods like nuts. Vegan carbohydrate sources such as grains, bread, potatoes, and energy gels offer comparable calorie content to non-vegan counterparts, serving as effective workout fuel. Tracking calorie consumption via an app for a few days can help ascertain if adjustments are necessary.

Calcium and Vitamin D

Calcium is a vital mineral crucial for heart, muscular and nervous system function, especially bone health. Inadequate calcium intake can lead to osteopenia, a concerning decrease in bone density that could progress to osteoporosis, characterized by brittle bones prone to fractures. Given the low-impact nature of cycling and its minimal weight-bearing aspect, cyclists must ensure sufficient calcium intake. Adults up to 50 years old should aim for daily calcium intake between 1,000mg and 2,500mg, with older adults potentially requiring more¹⁷.

Dairy products are the primary sources of calcium, potentially placing plant-based athletes at risk of inadequate intake. However, calcium can also be obtained from plant sources like green leafy vegetables, seeds, beans, and almonds, with additional calcium found in non-dairy milk alternatives such as oat milk¹⁸. A diverse diet encompassing these foods likely offers sufficient calcium levels. Notably, calcium absorption necessitates Vitamin D¹⁹, another nutrient often deficient in plant-based diets. While the skin can synthesize Vitamin D from sunlight, some athletes might require supplementation, warranting consultation with a healthcare provider.

Vitamin B12

Vitamin B12, also known as cobalamin, is a complex vitamin molecule essential in minute quantities—a recommended daily intake of 2.4 micrograms for adults²¹. Despite the minimal requirement, B12 plays a pivotal role in red blood cell formation, nerve function, and DNA structure. Inadequate B12 intake can lead to various health issues, starting with numbness and fatigue, progressing to anemia, cognitive decline, and severe neurological complications if left unaddressed²².

Plant-based athletes face particular B12 challenges as only animal products reliably provide B12 unless supplemented. Fortunately, B12 can be derived from non-animal microbial sources and utilized to fortify foods. Common non-animal B12-fortified foods include plant-based milk, breakfast cereals, nutritional yeast, and certain veggie burgers. Regular consumption may suffice, but vigilance in checking labels and considering supplementation is advisable.

Ironically, adherence to a well-planned plant-based diet significantly reduces B12 deficiency risk compared to meat eaters. Consistent consumption of B12-fortified foods or supplements can mitigate B12 inadequacy risks associated with a plant-based diet.

Protein

Protein serves as the foundation of life, essential for tissue building, repair, hormone production, enzyme synthesis, and to a lesser extent, energy supply. While dubbed a singular entity, protein comprises an extensive range of intricate molecules (potentially over 80,000 in the human body²³). Each protein consists of various amino acids, with nine being essential, necessitating external acquisition through dietary protein²⁴. Plant-based athletes encounter challenges in two protein aspects: quantity and quality.

Protein Quantity

The primary concern for plant-based athletes regarding protein pertains to meeting daily requirements. Omnivorous diets derive a substantial portion of protein from animal sources like meats and dairy products¹⁴, and eliminating these necessitates adequate plant-based substitutes to avoid protein insufficiency.

Fortunately, plant-based protein sources abound, with many offering higher protein content per calorie than animal-derived foods. However, plant proteins are typically less digestible, biologically available, and efficiently utilized than animal proteins. Hence, plant-based diets typically necessitate higher overall protein intake than omnivorous diets²⁵. Given that endurance athletes often require additional protein, most experts recommend plant-based athletes consume substantial protein—ideally 1.3–1.8 g/kg body weight daily, with some suggesting higher amounts. For instance, a 150 lb cyclist may need to consume protein equivalent to that found in about four cans of beans or six veggie burgers daily.

To fulfill protein requirements, divide protein intake across meals as the body can only process limited amounts at once. Moreover, vary protein sources to enhance diet diversity, addressing the primary protein challenges faced by plant-based athletes.

Protein Quality

Not all proteins offer the same biological utility to the body. While the term “protein” denotes a spectrum of amino acid complexes, certain protein sources provide all essential amino acids (termed complete proteinsincomplete proteins). Plant proteins often lack essential amino acids compared to animal proteins, with leucine commonly deficient in vegan diets.

The solution for incomplete proteins is diversity. By consuming a broad array of protein sources daily, athletes can complement amino acid deficits in one food with another. Some plant proteins such as soy, buckwheat, and quinoa are nearly complete or complete²⁷. Despite this, plant proteins are typically less readily absorbed by the body than animal proteins, necessitating higher overall protein consumption on plant-based diets^{25, 28}.

Other Essential Nutrients

Plant-based diets sometimes pose challenges in meeting requirements for certain essential