A Woman Making A Plant Based Smoothie In Her Kitchen

Optimizing Nutrition for Endurance Athletes Who Use a Plant-Based Diet

BY Elizabeth Inpyn

As a coach, it's important to meet athletes where they're at and support their goals by understanding their dietary preferences. Yet it's essential to assess an athlete's fueling needs to ensure maximum performance.

As a coach, one key part of your job is meeting your athletes where they’re at and supporting their goals. This is important in both training and fueling. It’s likely they will be bringing unique dietary preferences, cultural traditions and, unfortunately, many diet and nutrition myths/misinformation with them. The best way you can help is to understand why they eat the way they do, address any nutrition concerns and refer them to a sports dietician or nutritionist when needed.

Defining the Plant-Based Diet

To set the stage for this discussion, it’s important to define a few key concepts: what is plant-based versus vegan versus vegetarian? Plant-Based (PB) refers to a diet that consists largely or solely of vegetables, grains, pulses or other foods derived from plants rather than animals. PB allows room for flexibility as many will have different definitions of what constitutes “largely derived” and if/when animal products are included.

Something common I hear an athlete says is, “my diet is mostly plant-based,” meaning some include fish or eggs but not red meat, while others might do dairy but not meat of any kind. Vegan and vegetarian are a bit more structured. Vegan is defined as someone who won’t eat animal products or byproducts – no meat, dairy, honey or eggs. Vegetarians typically include dairy products and occasionally eggs. Asking your athletes for specificity will help in guiding and planning ways to meet their nutritional requirements.

Media-Amplified Misconceptions

Due to the vast amount of misinformation in typical media, social media and within certain subcommunities, it’s necessary to understand the “why” behind someone’s choice to eat a PB diet. At no point should you, as a coach, judge your athlete’s dietary decisions. However, you can and should step in if you feel like they are malnourished, underfueling or eating a particular way because of (unscientific) cultural ‘fad diet’ trends.

When the documentary Game Changers came out, there was a surge in athletes going to PB. This article is not about arguing the merits/falsehoods of that program or the PB diet in general. However, I will point out that while PB is a very healthy and potentially beneficial diet, it is not the magical, life-extending path the documentary made it out to be. Many of the claims were exaggerated or misrepresented. Another dark side of PB that I’ve seen reflected in athletes is the belief that it will drastically decrease weight and can be used as an excuse to control and underfuel. This is problematic on many levels.

PB can be appropriate and encouraged when an athlete is doing it for ethical, moral and medical reasons. They may also have food allergies or preferences that lean towards PB and should be taken into consideration.

The Science of Plant-Based Diets

So, what does the science tell us about PB? If done correctly and consistently, a plant-based diet, like any diet that is based on whole, minimally processed foods, can have both health and performance benefits. There is research to support that a whole food diet can reduce the risk of heart disease, lowered LDL and blood pressure, lowered incidence of Type II Diabetes and certain cancers, in addition to promoting recovery from training and lowering overall inflammation.

In turn, a poorly constructed PB diet can predispose athletes to macro (protein) and micronutrient (B12, Vitamin D, Calcium, Iron and Omega 3) deficiencies. With the strategic management of food and appropriate supplementation, a nutrient-rich plant-based diet can be designed to achieve the dietary needs and performance goals of most athletes. The most common nutrient deficiencies in plant-based athletes are listed below, as well as suggestions on how to address and supplement their diet.

Specific Factors to Monitor and Manage

The biggest concern when it comes to any diet is if it is providing sufficient energy to achieve energy balance. Data suggests that often, particularly in endurance sports, there is a negative energy balance, and many athletes are not meeting their needs. The consequences of insufficient energy balance are important to note; compromised immunity, low bone density, hormonal irregularities, reduced strength and muscle mass, a lack of training adaptations and lowered work capacity. I mention this because it can become a bigger problem when athletes have dietary restrictions (plant-based) that limit food options and availability.


The consensus amongst sports scientists is that athletes need more protein than is currently being recommended. 1.6-2.0g/kg body weight per day, and up to 2.2g/kg per day for older athletes (to prevent sarcopenia and account for muscle loss as we age). A plant-based diet can present challenges in meeting those requirements while also staying in energy balance. Plant sources of protein are often higher in carbohydrates and fat than animal sources, and this needs to be thoughtfully considered. PB athletes must focus on quantity AND quality due to absorption/digestibility issues and lowered amino acid content. Especially important is the amino acid Leucine, which is the primary trigger for muscle protein synthesis.

How to check the box: PB athletes should include tofu, tempeh, lentils, edamame, legumes, vegan protein powder and grains like kamut/amaranth/teff/quinoa daily.

Omega 3’s

Due to the absence of marine-sourced fats, PB athletes appear to consume significantly less n-3 fatty acids (DHA, EPA) than their animal-eating teammates. N-3 fatty acids play an important role in cardiovascular health, normal growth and development, and inflammatory and chronic disease. In terms of performance implications, n-3 fats might also increase nitric oxide production, assist with MPS, and improve heart rate variability.

How to check the box: If athletes will not eat fish sources of Omega 3’s, they will likely need to supplement or be very mindful to include enough chia seeds, algae oil, hemp seeds, walnuts and flaxseeds.

*Keep in mind that these sources are high in healthy fats, which must be taken into consideration for energy balance.

Vitamin D

Vitamin D, a fat-soluble vitamin produced in the skin, is essential for calcium absorption and bone health and plays an important role in many physiological processes key to endurance sports. While we are able to synthesize it from sunlight, Vitamin D can also be found in animal-based and fortified foods. Getting enough Vitamin D through sun exposure alone is hard, so many athletes, plant-based or otherwise, will look to supplement.

Poor vitamin D status negatively affects muscle strength and oxygen consumption, which confirms that supplementation can protect against overuse injury via its role in calcium metabolism and skeletal muscle function. If you have an athlete that’s chronically injured – assess for low Vitamin D levels.

How to check the box: After blood testing confirms a deficiency, supplement with Lichen-derived D3 1000-5000IU/day until levels stabilize. Incorporate foods like wild mushrooms, fortified nut milks, fortified cereals, tofu and eggs/cheese if your athlete isn’t 100% plant-based.

Vitamin B12

B12 (Cobalamin) is synthesized from anaerobic microorganisms in the rumen of cattle and sheep; therefore, PB athletes won’t be ingesting B12 unless it’s through supplementation. B12 is important for cell metabolism, brain and nerve function and the formation of blood. For women specifically, higher B12 levels are associated with enhanced athletic performance. Adequate levels of B12 also provide the body with an increased ability to deliver oxygen, thus possibly enhancing endurance capacity.

How to check the box: Luckily, many products now are fortified with B12, and supplementing is inexpensive and efficient. Cereals, some packaged oats, nut milks and plant-based meats are the most consistently fortified products, but nutritional yeast, tempeh and nori seaweed also naturally contain small amounts of B12 that can add up when consumed regularly.


The main source of iron in the plant-based diet is found in the non-heme form, which is less bioavailable than the heme iron found in animal products. PB diets also commonly contain dietary inhibitors such as the polyphenols tannin (found in coffee, tea, and cocoa) and phytates (found in whole grains and legumes), which can reduce the amount of iron absorbed from the diet. Research into the iron status of plant-based athletes has found that female PB appear to have lower iron stores than female omnivores and are more prone to iron-deficiency anemia.

How to check the box: Choose whole food iron sources (legumes, nuts, seeds, green vegetables), reduce consumption of inhibitor-containing foods like coffee/tea when eating iron-rich meals, consume foods rich in Vitamin C to enhance absorption and incorporate soaked/sprouted or fermented foods regularly. Monitor iron status through blood testing and consider supplementation.


Necessary for blood clotting, nerve and muscle stimulation, and skeletal health; calcium is found in a variety of foods, but mostly dairy products. Calcium loss has been found to be worse during phases of caloric restriction or underfueling, which, as discussed earlier, can happen more frequently in plant-based athletes.

How to check the box: Aim for 1000mg/day via tofu (calcium set), fortified plant milks and juice, kale, broccoli, sprouts, cauliflower and bok choi.

Product Recommendations

There are many NSF/Informed Sport certified products on the market today, giving PB athletes a variety of options. Companies like Momentous, Vega, Garden of Life, Hammer Nutrition, Gnarly, Spring Energy and Skratch Labs all have excellent options.

Encourage athletes to read labels and try different products for taste, efficacy and minimal GI discomfort. Don’t let “plant-based” be used as an excuse to skip or neglect proper in-session fueling.

Coach Checklist for PB Athletes:

Keep in mind this list works with all athletes and should be implemented when onboarding and throughout the season.

  • Is this athlete fueling for the work required? Are they meeting their daily caloric needs?
  • Does this athlete have a healthy relationship with food — are they choosing a particular diet for the “right” reasons or using it for disordered eating and food control?
  • Is this athlete fueling correctly before, during, and after training sessions?
  • Is this athlete meeting their daily protein needs on a consistent basis?
  • Is this athlete deficient in any nutrients (as confirmed by blood testing) and what are they doing to remedy it?


Tuso, P.J. et al. (2013). Nutritional Update for Physicians: Plant-Based Diets. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3662288/

Image Of Screenshots Displaying How The Trainingpeaks And Fuelin Apps Sync Together

Plan Your Nutrition With Fuelin

Compatible Apps

Fuelin offers users a custom daily nutrition plan with macro targets based on your fitness goals, training plan, and individual biology. It syncs directly with TrainingPeaks to provide simple, personalized, and results-driven daily nutrition guidance based on your TrainingPeaks workouts.

Elizabeth Inpyn Photo Of Her On A Bike Drinking Out Of A Water Bottle
About Elizabeth Inpyn

Elizabeth is a former NCAA Division 1 swimmer and water polo player, multiple podium triathlete (Olympic and 70.3 distance) and a USAT National Qualifier. She’s a certified sports nutritionist, holds an ISSN and Plant-based nutrition certification, a Masters of Science in Applied Exercise Science: Sports Nutrition and a Bachelor of Science in Biochemistry from the University of California Santa Barbara. As a performance nutrition coach at Fuelin, Elizabeth helps professional and elite competitors and teams, recreational athletes and coaches achieve their health, performance and wellness goals.

Related Articles