The paper suggests going meat-free as advantageous in seeing improvements in heart health as endurance athletes have a higher-than-average risk for atherosclerosis and heart damage.
Writing in the journal Nutrients, the team from George Washington University School of Medicine and Health Sciences also believe the diet aids in sporting performance and recovery.
“It's no wonder that more and more athletes are racing to a vegan diet," says review co-author Dr James Loomis, medical director for the Barnard Medical Center.
"Whether you're training for a couch-to-5K or an Ironman Triathlon, a plant-based diet is a powerful tool for improving athletic performance and recovery."
The number of professional athletes adopting a vegan-diet appears to be on the rise with tennis star Serena Williams, Formula one world champion Lewis Hamilton and boxer David Haye crediting a plant-based diet for boosting sporting performance.
A plant-based diet is typically high in carbohydrates and as such may offer these performance advantages. In addition, the higher intakes of vitamin C, vitamin E, beta-carotene, and other antioxidants, as well as a higher antioxidant enzyme production may help explain the diet’s advantages.
Researchers have also found potentially beneficial effects of specific antioxidant-rich foods on exercise outcomes, notably beets, allium vegetables (e.g., garlic, onions, and leeks) and cherry juice.
Antioxidant supplements, such as vitamin E, vitamin C, beta-carotene, and glutathione, have been shown to reduce oxidative stress.
However, some researchers have suggested that they may delay muscle recovery, prevent some of the positive health effects of exercise, and block the improvement of insulin sensitivity associated with exercise.
As well as reducing oxidative stress, the review looks at seventy-seven studies from the past thirty or so years specifically a plant-based diet’s role in reducing inflammation.
Here, the review highlights a 2017 meta-analysis of 18 prior studies, in which vegetarian diets consumed over a two-year period were shown to reduce serum concentrations of inflammation markers suggesting an anti-inflammatory effect.
“The anti-inflammatory benefits of plant-based diets may stem from their antioxidant content, the absence of products that may be inflammatory or sensitizing, or the absence of pro-inflammatory fats,” the review suggested.
“A few studies have examined the possibility that specific foods with antioxidant activity (e.g., tart cherries, pomegranates, blueberries, blackcurrants, and watermelon) may decrease post-exercise inflammation and facilitate recovery.”
The diet’s role in promoting a leaner body mass was also discussed in comparison to a high-fat diet, which the researchers thought might act on cellular metabolism indirectly through their effects on the gut microbiome.
“Gut bacteria produce endotoxins that can enter the bloodstream and, in turn, influence cellular metabolism. High-fat diets appear to disrupt the intestinal barrier to the passage of endotoxins,” the review said.
Improved glycogen storage
The team also pointed towards the plant-based diet’s effectiveness in improving glycogen storage referencing a 2016 study of athletes participating in full and half Ironman triathlons, winter triathlons, and winter pentathlons.
Here, the study showed that fewer than half (46%) reported meeting the recommended carbohydrate intake for athletes training 1–3 hours per day (less than 6 grams per kilogram (g/kg) body weight per day).
The study thought because grains, legumes, and root vegetables are rich in complex carbohydrate, individuals who begin plant-based diets typically increase their intake of healthful carbohydrate.
“Like any endurance athlete, plant-based athletes just need more calories than less active people," says review co-author Dr Susan Levin, a board certified specialist in sports dietetics and director of nutrition education for the Physicians Committee for Responsible Medicine.
"And if they are eating a wide variety of nutrient-dense fruits, vegetables, grains, and beans, they will easily meet all of their nutritional needs."
Despite the benefits of a plant-based diet, the team recommended supplementing with a vitamin B12 supplement, essential for nerve function and blood cell formation, owing to the diet’s deficiency in that nutrient.
Published online: doi.org/10.3390/nu11010
“Plant-Based Diets for Cardiovascular Safety and Performance in Endurance Sports.”
Authors: Neal Barnard, David Goldman, James Loomis, Hana Kahleova, Susan Levin, Stephen Neabore and Travis Batts