Nutrition and rehabilitation after anterior cruciate ligament reconstruction: A systematic review

PURPOSE: As the impact of nutrition on rehabilitation and return to sport (RTS) after ACL reconstruction (ACLR) remains largely unexplored, this review aimed to review the current evidence on the role of nutrition in rehabilitation outcomes for ACLR patients, with as ultimate goal a safer and more successful RTS. METHODS: Systematic review, adhering to PRISMA. Studies were selected from PubMed, EMBASE, and Web of Science with as mean search strings 'ACL*' and 'Nutrition', and/or 'Diet*'. A broad approach was applied considering populations/patients of any age undergoing ACLR, with nutritional focus, including randomised and non-randomised trials, as well as observational studies. Data were extracted and analysed; risk of bias assessments by RoB 2 and ROBINS-I tools RESULTS: Fifteen studies were included. Two observational studies examined the effects of diet exposure, while 13 RCTs considered specific supplements, alongside any form of physical therapy. RTS was only considered in a single trial only. Serious risk of bias and critical issue were identified in the majority of the studies. This risk of bias and the variability across studies meant that there was not enough high-quality data to perform meta-analyses. Protein intake was associated with improved muscle mass retention and functional recovery. Flaxseed oil (omega 3 fatty acids) and leucine showed some promise. For vitamin-D, correcting insufficiency seemed warranted. CONCLUSION: A high protein intake along with physical rehabilitation is related to improved muscle mass and function, however the impact on RTS and other ACLR outcomes needs to be established. Supplements like leucine and flaxseed oil, and correcting vitamin D inadequacy deserve more attention. More high-quality research is needed to formulate specific personalised nutritional guidelines for ACLR rehabilitation. LEVEL OF EVIDENCE: Level NA.