Impact of Whey Protein on Bone Mineral Density: a Systemic Review and Meta-analysis

Previous studies have shown that whey protein and its basic protein fraction, milk basic protein, might have a beneficial effect on bone mass through promoting bone formation and suppressing osteoclast activity. Nonetheless, most studies do not have enough power to examine the potential benefit on bone mass from using whey protein and milk basic protein and the data are contradictory. The aim of our meta-analysis is to reveal the impact of whey protein and milk basic protein on bone mineral density (BMD). We comprehensively searched the databases of MEDLINE, EMBASE, and Cochrane databases. The inclusion criterion was published randomized control trials (RCT) comparing whey protein supplementation or milk basic protein to placebo or controls (non-whey protein). The primary outcome was the differences in the changes in BMD at the level of lumbar spine, hip, or femoral neck, which was primarily measured by dual-energy x-ray absorptiometry. We calculated pooled mean difference (MD) with 95% confidence intervals (CI) using random-effects model. Publication bias was assessed using funnel plot and Egger's regression test Six RCTs were included in the meta-analysis involving 562 subjects. Our collected studies utilized varying dose of whey protein from 25 grams to 75 grams per day and the dose of milk basic protein is 40 grams per day during a time frame ranging from six months to two years. There was a statistically significant improvement of BMD at the lumbar spine (MD= 0.014, 95% CI: 0.011 to 0.017, p-value < 0.05) favoring whey protein and milk basic protein group. There is a symmetrical distribution of studies in funnel plot. The Egger's test result was not statistically significant (P = 0.87). There was no enough studies to compare the difference of BMD at the hip or femoral neck. This is the first meta-analysis investigating the impact of whey protein and milk basic protein on BMD. Our study suggested that whey protein supplementation and milk basic protein, the basic protein fraction of whey protein, might have a positive impact on bone mineral density compared to placebo or controls. Using whey protein and milk basic protein should be considered to be a conjunctive treatment with current therapy to improve bone mineral density.