Dietary intake of fish, n-3 polyunsaturated fatty acids and risk of hip fracture: A systematic review and meta-analysis on observational studies

Previous studies have shown that fish consumption and dietary intake of n-3 polyunsaturated fatty acids (n-3 PUFAs) are associated with hip fracture; however, findings were conflicting. The present review aimed to summarize the current evidence on the association of fish consumption and dietary intake of n-3 PUFAs with hip fracture. The online databases of PubMed, ISI Web of Science, Scopus, ProQuest, Science Direct and Embase were searched until August 2017 for related publications using relevant keywords. To pool data, either a fixed-effects model or random-effects models were used. Cochran's Q tests were used to assess heterogeneity between studies. In total, 10 studies (7 prospective and 3 case-control studies) were included in this systematic review, and 9 studies with total sample size of 292657 participants were included in the meta-analysis. The age of participants was 20 years or older. Combining 8 effect sizes from 4 prospective studies and 2 case-control studies revealed a significant inverse association between fish consumption and risk of hip fracture (pooled effect size: 0.88, 95% CI: 0.79-0.98, P = 0.02). Although this relationship became non-significant in prospective studies, a significant inverse association was found in prospective studies with sample size of 10000 individuals or more, and studies that considered body mass index as a covariate. Furthermore, dietary intake of n-3 PUFAs was inversely associated with risk of hip fracture (pooled effect size: 0.89, 95% CI: 0.80-0.99, P = 0.02). Also, such relationship was seen after excluding one case-control study and combining effect sizes only from prospective studies (pooled effect size: 0.88, 95% CI: 0.80-0.98, P = 0.02). In conclusion, we found that fish consumption and dietary intake of n-3 PUFAs might have protective effects on bone health and decline the risk of hip fracture.