Vegetable but not animal protein intake is associated to a better physical performance: a study on a general population sample of adults

Background: The research was conducted in the frame of a population-based, case control study, called Genes Environment Interaction in Respiratory Disease. Objective: To assess the association between protein intake and physical performance in a general population sample. Design: Researchers investigated the association between the participants' dietary information and their physical performance using the 6-min walking test and the distance walked in metres (6MWD) as main outcome measure. Information on dietary intake was collected using the validated European Investigation into Cancer and Nutrition food frequency questionnaires (FFQs). Then, daily intake of energy and macronutrients was estimated by means of the NAF software (nutritional analysis of FFQ). Linear regression models were used to evaluate the associations between vegetable, animal and total protein intakes and the 6MWD. The models were adjusted for socio-demographic features, total fats and available carbohydrate intakes. Results: The participants were 223 subjects (57% females) aged between 23 and 68 years. Their mean vegetable and animal proteins intake for gram/kg of body weight/day were, respectively, 0.4 and 0.7. After adjusting for all the potential confounders, there was a significant increase of 20.0 (95% CI 0.8; 39.2) m in the distance walked for an increase in 10 g/day of vegetable proteins and non-significant variations of -1.8 (95% CI -9.3; 5.7) m for an increase in 10 g/day of animal proteins and of 0.5 (95% CI -6.8; 7.7) for an increase in 10 g/day of total proteins. Discussion and conclusions: Our result suggests a positive role of vegetable proteins on physical performance. Whether this result is related to the high protein intake itself or may be a consequence of the other properties of plant-based foods deserves further investigation.