Erythrocyte Omega‐3 Long Chain Polyunsaturated Fatty Acids Are Associated with Lumbar Spine but Not Whole Body Bone Mineral Density in Healthy Children
Authors: Parks Colleen A , Brett Neil R , Agellon Sherry , Lavery Paula , Vanstone Catherine A , Maguire Jonathon L , Rauch Frank , Weiler Hope A 
Published: November 2023

Since peak bone mass is achieved by the second decade of life, inadequate bone mineral accrual during childhood may greatly increase the risk of developing osteoporosis later in life. Therefore, it is important to investigate factors that influence bone mass during childhood in order to maximize bone mineral accrual. Omega‐3 long chain polyunsaturated fatty acids (n‐3 LCPUFA) have been observed to be beneficial for bone health in older adults by preserving trabecular bone; however, whether n‐3 LCPUFA have similar associations to bone in children remains unclear. The objective of this study was to investigate the relationship between erythrocyte (RBC) n‐3 LCPUFA and bone mineral density (BMD) in healthy children. Participants 2 through 8 y of age were recruited from previous studies conducted at the research unit and by handing out flyers at local daycares in the greater Montreal area. For this cross‐sectional analysis, dietary intake, socio‐demographic information and anthropometry were assessed using standard protocols. BMD was assessed at the lumbar spine (LS) vertebrae 1–4 and the whole body using dual‐energy X‐ray absorptiometry (DXA; Hologic Discovery APEX software version 13.3). RBCs were separated from a fasted blood sample and underwent a direct methylation reaction in order to measure the fatty acid profile via gas chromatography. Participants were classified into tertiles based upon the proportion of each respective fatty acid (ALA, EPA DHA, total n‐3 LCPUFA (sum of all RBC n‐3 LCPUFA), and the ratio of omega‐6 (n‐6) LCPUFA to n‐3 LCPUFA) to total RBC fatty acids. A mixed model ANOVA was performed to test for differences among the tertiles in relation to BMD. If data did not pass the normality test, it was log transformed prior to statistical analysis. The participants (n= 49, 5.64 ± 1.93 y) were 59% male, had a height z‐score of 0.35 ± 0.97 and had a BMI z‐score of 0.65 ± 0.84. Median proportions and interquartile ranges of the RBC LCPUFA are found in Table 1. Participants in the highest tertiles of EPA and total n‐3 LCPUFA had significantly higher BMD z‐scores at the LS compared to participants in the lowest and middle tertiles (p < 0.05) (Figure 1a, b). Similar trends were noted for tertiles of DHA; however they did not reach statistical significance (Figure 1c). In contrast, participants in the highest tertile for the ratio of n‐6 LCPUFA to n‐3 LCPUFA, had significantly lower BMD z‐scores at the LS compared to participants in the lowest tertile (p < 0.05) (Figure 1d). No significant differences among tertiles were observed for any of the n‐3 LCPUFA and BMD z‐scores for the whole body. These results suggest that n‐3 LCPUFA may positively influence bone mass during childhood and furthermore, n‐3 LCPUFA may have a greater impact on the mineralization of trabecular bone compared to cortical bone as the LS has a higher proportion of trabecular bone than the whole body.

Support or Funding Information

This work was supported by funding from Dairy Farmers of Canada, the Canadian Foundation for Innovation and Canada Research Chairs. Dairy Farmers of Canada did not have a role in design, implementation, analysis or interpretation.

Major omega‐3 long‐chain polyunsaturated fatty acids (n‐3 LCPUFA) in erythrocytes (% of total fatty acids) among forty‐nine healthy children 2 to 8 y of age.

Fatty Acid
Median
Interquartile Range

ALA
0.135
0.117 – 0.151

EPA
0.347
0.289 – 0.439

DHA
2.822
2.550 – 3.127

Total n‐3 LCPUFA
4.803
4.484 – 5.338

n‐6 LCPUFA to n‐3 LCPUFA ratio
6.585
5.779 – 6.912

ALA alpha‐linolenic acid, EPA eicosapentaenoic acid, DHA docosahexaenoic acid