Transfer of omega‐3 fatty acids across the blood–brain barrier after dietary supplementation with a docosahexaenoic acid‐rich omega‐3 fatty acid preparation in patients with Alzheimer's disease: the OmegAD study

Abstract Objective Little is known about the transfer of essential fatty acids ( FA s) across the human blood–brain barrier ( BBB ) in adulthood. In this study, we investigated whether oral supplementation with omega‐3 ( n ‐3) FA s would change the FA profile of the cerebrospinal fluid ( CSF ). Methods A total of 33 patients (18 receiving the n ‐3 FA supplement and 15 receiving placebo) were included in the study. These patients were participants in the double‐blind, placebo‐controlled randomized O meg AD study in which 204 patients with mild A lzheimer's disease ( AD ) received 2.3 g n ‐3 FA [high in docosahexaenoic acid ( DHA )] or placebo daily for 6 months. CSF FA levels were related to changes in plasma FA and to CSF biomarkers of AD and inflammation. Results At 6 months, the n ‐3 FA supplement group displayed significant increases in CSF (and plasma) eicosapentaenoic acid ( EPA ), DHA and total n ‐3 FA levels ( P < 0.01), whereas no changes were observed in the placebo group. Changes in CSF and plasma levels of EPA and n‐3 docosapentaenoic acid were strongly correlated, in contrast to those of DHA . Changes in DHA levels in CSF were inversely correlated with CSF levels of total and phosphorylated tau, and directly correlated with soluble interleukin‐1 receptor type II . Thus, the more DHA increased in CSF , the greater the change in CSF AD /inflammatory biomarkers. Conclusions Oral supplementation with n ‐3 FA s conferred changes in the n ‐3 FA profile in CSF , suggesting transfer of these FA s across the BBB in adults.