Effects of partial replacement of red and processed meat with non-soy legumes on bone and mineral metabolism and amino acid intakes in BeanMan randomized clinical trial.

The transition towards more plant-based diets may pose risks for bone health such as low vitamin D and calcium intakes. Findings for the contribution of animal and plant proteins and their amino acids (AAs) to bone health are contradictory. This six-week clinical trial aimed to investigate whether partial replacement of red and processed meat (RPM) with non-soy legumes affects AA intakes and bone turnover and mineral metabolism in 102 healthy 20-65-year old men. Participants were randomly assigned to diet groups controlled for RPM and legume intake (designed total protein intake [TPI] 18 E%): the meat group consumed 760 g RPM per week (25% TPI) and the legume group consumed non-soy legume-based products (20% TPI) and 200 g RPM per week, the upper limit of the Planetary Health Diet (5% TPI). No differences in bone (bone-specific alkaline phosphatase; tartrate-resistant acid phosphatase 5b) or mineral metabolism (25-hydroxyvitamin D; parathyroid hormone; fibroblast growth factor 23; phosphate; calcium) markers or calcium and vitamin D intakes were observed between the groups (P>0.05). Methionine and histidine intakes were higher in the meat group (P≤0.042), whereas the legume group had higher intakes of arginine, asparagine, and phenylalanine (P≤0.013). Mean essential AA intakes in both groups met the requirements. Increasing the proportion of non-soy legumes by reducing the amount of RPM in the diet for six weeks did not compromise bone turnover and provided on average adequate amounts of AAs in healthy men, indicating that this ecologically sustainable dietary change is safe and relatively easy to implement.