This week I’d like to change up my normal article style by delving into one of the major nutritional dilemmas facing the athletic community today: the vegan diet. With a sharp rise in animal rights groups and interest in the morality of consuming meat, more and more people are turning to meatless vegetarian and even vegan diets. For the majority of the population, there is no reason for worry over the content of such a diet; many of us could stand to eat more fruits and vegetables anyway. But as an athlete myself, I’ve always remained skeptical as to whether or not a vegan diet could provide the same nutritional value to power the body through the rigors of high level athletics to as a more traditional diet without the same restrictions. So I did some research, and here is what I found.
DISCLAIMER: This article is in no way commenting on the motivations behind consuming or not consuming meat in one’s diet. It is simply meant to provide an overview of scientific research as to whether or not athletes ought to be concerned about the nutritional content of either a meatless or meat-included diet versus the other.
Of the utmost importance to any athlete are their energy levels for performing their sport. A lack of macronutrients that results in fatigue and lethargy will negatively impact performance, which is why any athlete that takes their diet seriously will be able to tell you what they eat, how much, and in what proximity to a training session in order to maximize energy levels during performance. Insufficient energy levels typically connote a hypocaloric diet as well, leading to unwanted loss of body mass, be it body fat or muscle content. According to a 2017 study by David Rogerson, herbivorous diets are at a higher risk than omnivorous diets for failing to provide the energy necessary to maintain body mass and perform athletic activities to a high level. Rogerson affirms that the issue of maintaining sufficient energy levels “is likely to be compounded further when a habitual diet promotes early satiation and reduced appetite, such as a vegan diet.” He also comments on how large data sets show that less “energy,” presumably carbohydrates and fats, are consumed by vegans on average as compared to those who consume omnivorous diets. This does not mean it is impossible for herbivorous diets to provide sufficient energy to perform athletic activities to high levels; Rogerson does also admit that adding higher quantities of foods like nuts, oils, and seeds may help raise dietary energy and caloric intake levels. Perhaps this disconnect is a lack of nutritional education, socioeconomic factors like access to such foods (in my experience they tend to at least be associated more heavily with suburban, upper middle class grocery stores), or some other factor; I am not qualified to say. This is simply a risk to be mitigated.
Stereotypically, it is bounded around that herbivorous diets struggle to include protein as a result of the absence of meat. This is a question it is very important to solve, as protein is the building block of the body. Without protein, there is no muscle mass. Further, according to Rogerson athletes need even more protein than the average human as well. It turns out that vegans do in fact consume less protein on average than omnivores, according to a 2021 study by Sliz et. al.
However this is not the major concern, for as has correctly been pointed out for years, there are plenty of sources of protein within the vegan diet. The issue remains the type of proteins the vegan diet prohibits. A 2007 article by Campbell et. al. confirms that herbivorous proteins sources are lacking. They contain less branch-chain amino acids (BCAAs), which are crucial to building muscle, as well as a lower leucine content. Leucine in particular is vital to muscle protein synthesis (MPS), as well as playing a large role in muscle recovery from athletically-induced stress. In addition, milk-based protein sources tend to be best for triggering MPS due to their high BCAA content (Hartman et. al., 2007), which does not bode well for vegan diets specifically. Again, this does not mean herbivorous diets cannot compensate. There are plenty of supplements for BCAAs and other protein sources. It simply means that herbivores must remain cautious of their protein intake or risk muscular damage or atrophy.
Vitamin B12 and Iron Deficiency
Pawlak et. al. 2016 discuss the risk of vitamin B12 deficiency as a result of a lack of dairy products in the vegan diet. Colabamin is the main source of vitamin B12, and is found in high proportions in dairy milk, whereas it is highly rare in plant-based foods. Vitamin B12 is especially important for athletes, as it is crucial for energy metabolism–the processing of carbohydrates and fats into useable energy. Additionally, a general lack of the vitamin will result in a weakened nervous system and poor blood cell health. The nervous system is especially important for athletic performance, as in sports like powerlifting, bodily performance is dependent upon nervous system coordination with muscle tissue to allow for optimal firing of muscle fibers.
Similarly, Iron consumption may be an issue for herbivores. Given their whole grain-rich diets, vegans and vegetarians do in fact consume enough–however, much of plant-based sources of Iron are biounavailable. This is because much of plant-based Iron is of the non-haem variety, which is far less bioavailable than the haem variety, which is richly present in meat. Further, many herbivorous diets are rich in Iron absorption inhibitors like polyphenols and phytates, which limit Iron absorption from the blood stream (Hunt, 2002). Iron is incredibly vital for athletes, as it plays major roles in energy metabolism and Oxygen transfer in the blood. Thus low Oxygen levels are especially hard on endurance athletes.
Again, substitutes exist in the form of supplements, but this does not change the general struggles of herbivorous diets to provide proper nutritional value for athletes.
This article is by no means all inclusive; I am limited by my word count, even if I have more than exceeded it at this point. From what I have gathered together here, it seems to me that a vegan diet can indeed support a top level athlete, but there are many risks associated and caloric as well as macro and micronutrient intake must be monitored closely to avoid adverse effects on bodily health and performance. For more information, I recommend the Rogerson article I reference above. He does a great job covering all angles of the debate, providing a wide range of information, and linking further academic sources of multiple eras. Whatever your activity level, dietary intake, and level of dietary care, be safe everyone.