Updated: Nov 11, 2020
Vegan Diets for Adolescents: A Sports RD’s Perspective Laura Moretti, MS, RD, CSSD, LDN
Vegan diets have been in existence for years; however, it seems that more recently they have made their way into the mainstream through the channels of social media, athletes, and celebrities toting the miraculous benefits of a plant-based lifestyle. Although vegan diets are not new, the prevalence of them in our society appears to be growing by the day. Vegan diets are 100% plant-based and exclude any products containing or derived from animal-based products. A vegetarian diet is also plant-based but may contain products that are derived from animals such as dairy, honey, and eggs. So, how do we know which is the best lifestyle to choose: omnivore, pescatarian, vegetarian, vegan? An omnivore is a person that consumes animal proteins, where a pescatarian consumes mainly a plant-based diet, but also includes seafood, dairy, and eggs. Vegetarians consume plant-based proteins but also include eggs and dairy products.
As a sports dietitian, my focus is on ensuring that adolescent athletes are properly fueled and maintaining energy balance to support optimal growth and performance. A negative energy balance or inadequate energy intake can have a negative impact on many systems in the body including hormonal, bone health, psychological, and hematological (Mountjoy). Aside from the negative health consequences there are also significant performance consequences such as decreased endurance performance, increased recovery time, and decreased training response. Vegan diets, although very high in nutrient density, tend to be low in energy density which can lead to inadequate caloric intake. Athletes have elevated caloric needs which can be hard to meet on a high volume, low density diet.
Often when someone chooses a vegan diet they tend to focus more on the foods that they “cannot” eat, rather than focusing on the foods that they “need” to eat in order to obtain nutrients that are often lacking in plant-based diets (Mangieri). Animal proteins including eggs, fish, beef, and poultry and are excellent sources of B12, iron, zinc, calcium, protein, and vitamin D. Therefore, removing these items from the diet creates a void that must be filled in order to keep a body functioning and performing well. Deficiencies in these nutrients can lead to issues such as decreased bone density, muscle loss, fatigue, and decreased immune functioning. Animal proteins contain all the essential amino acids in one food. Plant-based proteins are incomplete proteins; therefore, different plant-based protein sources must be combined in order to form a complete protein. This can be done, but often requires additional planning and effort. Knowing most of my high school athletes, having enough time in the day is often one of their biggest challenges.
Plant-based diets also tend to be very high in volume as well as fiber. Fiber is beneficial and necessary in the diet and it is recommended that we obtain 25-35 grams per day. Individuals following vegan diets often double or even triple this amount. So can you have too much of a “good” thing? The answer is: absolutely! High-fiber diets lead to early satiety and reduced appetite which can contribute to energy deficiency in growing athletes. High fiber diets are also known to cause gas, bloating, and diarrhea. Greater than 35 grams per day of fiber can interact with protein and fat, and decrease the digestibility of proteins, carbohydrates, and fats. The decreased transit time which occurs as a result of a high fiber diet can cause decreased absorption of calcium and other minerals.
The bottom line is that an individual deciding to choose a vegan diet should be aware of the potential risks of the under consumption of vital nutrients.
In an adolescent population that can be particularly vulnerable to the messages of social media and frequently uninformed about how to execute this properly, the risk outweighs the potential benefit. If an individual still feels strongly about a plant-based lifestyle, I encourage them to adopt a vegetarian diet. Vegetarian diets include eggs and dairy which can support optimal bone growth and development as well as increases the variety of food choices that are available. A multivitamin may also be beneficial with any dietary restriction (including food allergies such as dairy or gluten).
It is our practice to recommend that an athlete thinking of making a change to a vegetarian or vegan diet meet with a registered dietitian to ensure they are covering all of their nutritional bases.
References — Mangieri, H. (2017) Fueling Young Athletes. Champaign, IL: Human Kinetics. — Melin, A et al. Low-energy density and high fiber intake are dietary concerns in female endurance athletes. Scand J Med Sci Sports. 2016 Sep;26(9):1060-71. — Mountjoy M et al. IOC author consensus statement update 2018: Relative Energy Deficiency in Sport (RED-S). BJSM, May 2018.