There has been increasing interest in meat-free diets in recent years, with more and more people interested in switching from animal to plant sources of protein for health, sustainability and ethical reasons.
Yet researchers at the Arizona State University in the US said despite well-documented health benefits of vegetarian diets, little research had been done on the impact on athletic performance.
According to 2015 Mintel research in Germany, while only 7% of adults claim to follow a vegetarian diet, more than a third (33%) say they are actively reducing their red meat consumption and 19% say they are incorporating more vegetarian foods into their diet compared to a year ago.
Less protein, more antioxidants
“In spite of the many health aspects of vegetarian diets some concern has been raised pertaining to the nutrient adequacy of vegetarian diets for
supporting athletic performance,” they wrote in the journal Nutrients.
“Vegetarian diets are typically lower in vitamin B12, protein, creatine, and carnitine, and iron and zinc from plant sources are less bioavailable than from meat sources. However, vegetarian diets are typically higher in carbohydrate and antioxidants, which may be advantageous for athletic performance, particularly for endurance activities.”
Looking at 27 vegetarian and 43 omnivore elite adult endurance athletes, they tracked maximal oxygen uptake (VO2) on a treadmill and strength in leg extensions.
Detailed seven-day food logs showed that although total protein intake was lower among vegetarians in comparison to the meat-eaters, protein intake as a function of body mass did not differ.
Comparing the results of the strength and VO2 tests, they found vegetarian women had better results while for men there was no significant difference between the vegetarians and meat-eaters.
The female vegetarians had a 13% greater VO2 maximum score than their meat-eating competitors.
“This gender difference is intriguing and merits further investigation in future studies,” they wrote.
Peak torque, or force, in the leg extensions were not significantly different between the two diet groups.
Backing for vegetarianism
“This study suggests that following a vegetarian diet may adequately support strength and cardiorespiratory fitness development, and may even be advantageous for supporting cardiorespiratory fitness,” the researchers wrote.
“Certainly many factors affect an athlete’s sports performance, and there is no dietary substitute for quality training. However, our study contributes to the literature about cardiorespiratory and strength comparisons between vegetarian and omnivore endurance athletes, and may provide a rationale about the adequacy of vegetarian diets for sport performance.”
Organisations like the Vegan Society have said high profile cases of vegan and vegetarian sportspeople have helped cast off outdated stereotypes of pasty protein and iron-deprived animal lovers.
“Vegan athletes play an integral part in furthering the [vegan] movement. From Carl Lewis in the early 1980’s to the Williams sisters in tennis today, there have been so many influential vegan athletes. Their success has shown everyone that you simply don’t need animal products to compete at the very top of any sport,” Vegan Society media manager, Jimmy Pierce, told us in the past.
The Arizona researchers called for larger trials to confirm the conclusions.
2016, 8(11), 726, doi:10.3390/nu8110726
“Cardiorespiratory Fitness and Peak Torque Differences between Vegetarian and Omnivore Endurance Athletes: A Cross-Sectional Study”
Authors: H. M. Lynch, C. M. Wharton and C. S. Johnston