Effect of n‐3 polyunsaturated fatty acid on bone health: A systematic review and meta‐analysis of randomized controlled trials

Bone metabolism is a complicated process, which involves bone modeling and remodeling. If this process is unbalanced, bone loss and resultant osteoporosis might occur. Recently, nutrition supplementations such as n‐3 polyunsaturated fatty acids (PUFAs) are considered to be used on improving the bone metabolism and reducing the risk of osteoporosis. To more precisely assess the effects of n‐3 PUFA supplementation on bone mass and clarify its potential mechanism, we have conducted a systematic review and meta‐analysis. Based on the strict inclusion and exclusion criteria, 12 articles were included in this meta‐analysis. The results in articles show that n‐3 PUFAs could slightly enhance the level of bone mineral density (BMD) (0.005 g/cm(2); 95% CI, 0.000–0.010) (n = 7), which was the primary outcome for the research in comparison with the control group. In addition, the results also illustrate that the increasing effect on BMD (0.024 g/cm(2); 95% CI, 0.020–0.028) became more significant for postmenopausal women. N‐3 PUFAs had no significance on the level of bone‐specific alkaline phosphatase (BALP) (−0.24 µg/L; 95% CI, −0.86 to 0.39) and osteocalcin (−0.63 μg/L; 95% CI, −1.84 to 0.57) (n = 5), which are the specific markers of bone formation. When compared with the eicosapentaenoic acid + docosahexaenoic acid supplementation, the supplementation form of α‐linolenic acid significantly increased the content of BALP (0.396 µg/L; 95% CI, 0.069–0.724). The effects of n‐3 PUFAs on bone resorption biomarkers containing type I collagen cross‐linked C‐terminal peptide (CTX) and type I collagen cross‐linked N‐terminal peptide (NTX) are considered and used in our study. Results indicated that participants who received n‐3 PUFAs significantly decreased the level of CTX in the human body (−0.367 μg/L; 95% CI, −0.726 to −0.007) (n = 4). However, there was no significant difference in NTX levels in humans after supplementation with n‐3 PUFA (−1.744 µg/L; 95% CI, −3.970–0.481) (n = 3). For postmenopausal women, it presented a significant decreasing level of CTX (−0.393 µg/L; 95% CI, −0.651 to −0.135) and NTX (−2.082 µg/L; 95% CI, −2.970 to −1.195) within their bodies. In conclusion, these findings suggested that n‐3 PUFAs might have a beneficial effect on bone health, especially for α‐linolenic acid supplementation form or for postmenopausal women.