Dietary intake of semi-professional soccer players after 8-week vegan intervention – results of the VegInSoc study

Introduction: Despite the growing interest among athletes in embracing plant-based diets, adequate research remains to investigate the impact of a vegan diet in soccer. In this pilot study, we aimed to assess the effects of an 8-week vegan diet (VEG) intervention on the nutritional status of semi-professional soccer players compared to an omnivorous control group (CON).

Methods: A total of 18 subjects participated in this controlled, non-randomized pilot study. To determine the dietary intake, the subjects fulfilled a 3-day dietary weighed record at three time points: before the intervention (t0), at the beginning of the intervention (t1), and at the end of the intervention (t2). 

Results: The vegan intervention led to increased consumption of legumes, plant-based spreads, meat and dairy alternatives, along with a higher intake of vegetables, fruits, and nuts compared to the CON group. This led to an overall higher carbohydrate (e.g. t2: 46.2 ± 7.75 vs. 37.6 ± 2.80 En%; p = 0.035) and lower protein intake (e.g. t2: 1.13 ± 0.41 vs. 1.68 ± 0.70 g/kg BW; p = 0.084) in the VEG group. However, energy and carbohydrate intakes were below the recommended levels in both groups with only the CON group meeting protein recommendations. Fat intake slightly increased over time in both groups (VEG: +4.36 En%, CON: +4.87 En%). As expected, magnesium (+ 198 mg) and iron (+ 9.07 mg) intake increased in the VEG group during the intervention.

Conclusion: Based on our findings, it can be concluded that a short-term vegan diet can increase the supply of carbohydrates, magnesium, and iron but should be well-planned to ensure the supply of energy and protein. However, further research involving long-term intervention studies is needed to better understand the impact of a vegan diet on soccer players.