by Jack Norris, RD, LD
In February of 2021, I published an extensive article on vegan bone health, Bone Fractures among U.K. Vegans: Implications and Recommendations. In that article, I recommend resistance training for optimal bone health in vegans. We now have evidence for that recommendation.
Wakolbinger-Habel et al. (Austria, 2022) performed a cross-sectional study on the bone health of four groups of people aged 30 to 50: 20 vegans (9 F, 11 M) and 25 omnivores (8 F, 17 M) who performed resistance training at least once a week and 23 vegans (13 F, 10 M) and 20 omnivores (15 F, 5 M) who did no resistance training. There was little difference in bone health between vegans who performed resistance training and omnivores. Vegans who didn’t perform resistance training had poorer bone health. The duration of the vegan diet had no influence on bone microarchitecture. Vegans performing exclusively aerobic activities (n = 16) and vegans performing no sports activities at all (n = 6) had similar bone microarchitecture. The differences in bone couldn’t be explained by any obvious differences in nutrition. The researchers concluded that resistance training seems to be particularly important to preserve bone health when adhering to a plant-based diet.
I’ve added two recent studies to our article, Weightlifting for Vegans, that shed light on the protein needs of vegan athletes.
Hevia-Larraín et al. (Brazil, 2021) studied changes in leg muscle strength and size among 19 male vegans and 19 male omnivores. The participants had to have followed their diet for at least one year. Participants’ protein intakes were increased to 1.6 g/kg of body weight per day, through supplemental soy protein for vegans or whey protein for omnivores, and they followed a lower-body resistance training program for 12 weeks. Muscle mass and size increased among both groups with no statistically significant differences. The authors cautioned that meeting 1.6 g/kg of protein per day would be difficult on a whole foods, plant-based diet and noted that the soy protein isolates the study participants were consuming had been stripped of any factors that might block protein absorption from whole plant foods. At the time this study was conducted, no other study had compared the effects of protein source between vegans and omnivores in response to exercise; therefore, this study suggests that 1.6 g/kg of protein is enough for vegans to match omnivores in gains of muscle strength and size but that much protein might not be required. The study by Conrado de Souza et al., described below, suggests that closer to 1.0 g/kg of protein might be enough.
Conrado de Souza et al. (2022, Brazil) compared the squat, handgrip strength, isometric deadlift strength, jumping, and maximum aerobic speed between a group of physically active, 18 to 40 year-old, male and female vegetarians (9 vegans, 23 lacto-ovo-vegetarians) and 26 omnivores. The only differences between the groups were that the vegetarians had higher “relative strength” and jumping scores, possibly as a function of weighing slightly less. This was apparently the first strength study that compared already-physically active vegetarians and omnivores. The vegetarians had a protein intake of 1.0 g/kg of body weight compared to 1.6 g/kg for the omnivores.
The ideal amount of protein for vegan athletes appears to be between 1.0 and 1.6 g/kg of body weight. My general recommendation is for serious strength athletes to err on the side of closer to 1.6 g/kg but monitor gains in relation to protein intake; it could be that 1.6 g/kg isn’t necessary for optimal strength for most vegan athletes.
