Fatty acid profile in patients with phenylketonuria and its relationship with bone mineral density

Background Patients with phenylketonuria (PKU) undergo a restrictive vegan-like diet, with almost total absence of n-3 fatty acids, which have been proposed as potential contributors to bone formation in the healthy population. The PKU diet might lead these patients to bone mass loss and, consequently, to the development of osteopenia/osteoporosis. Therefore, we proposed to analyze their plasma fatty acid profile status and its relationship with bone health. Methods We recruited 47 PKU patients for this cross-sectional study and divided the cohort into three age groups (6-10 years, 11-18 years, 19-42 years). We measured their plasma fatty acid profile and bone mineral density (BMD) (both at the femoral neck and the lumbar spine). Seventy-seven healthy controls also participated as reference values of plasma fatty acids. Results Docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) and total n-3 fatty acids were significantly diminished in PKU patients compared with healthy controls. DHA, EPA, and total n-3 fatty acids were also positively associated with bone mineral density (r=0.83, p=0.010; r=0.57, p=0.006; r=0.73, p=0.040, respectively). There was no association between phenylalanine (Phe), Index of Dietary Control (IDC), calcium, 25-hydroxivitamin D concentrations, daily calcium intake, and BMD. Conclusion Our results suggest a possible influence of essential fatty acids over BMD in PKU patients. The lack of essential n-3 fatty acids intake in the PKU diet might affect bone mineralization. Further clinical trials are needed to confirm the effect of the n-3 essential fatty acids on bone accrual in a cohort of PKU patients.