**5.2 DHA and neurovascular unit**

The concept of neurovascular unit emphasizes the intimate relationship between the brain and its vessels, particularly the coupling between neural activity and cerebral blood flow [43]. Although the role of DHA neurolipidomics in neurovascular coupling appears to be underestimated, substantial experimental evidence suggests that the morphologic and functional integrity of the neurovascular unit largely depends on high DHA enrichment [37, 40, 43]. Moreover, the potential role of EPA in microvascular function further supports the evolutionary importance of these essential nutrients to maintain efficient functional couplings between neural and vascular networks [28, 29]. A functional neurovascular unit may be crucial not only for neurovascular coupling but also for BBB integrity and neurogenesis.

A regular dietary supply of DHA is required to preserve normal brain and retinal function. Under physiologic conditions, the net DHA incorporation rate for the entire human brain is very low and equivalent to the net rate of DHA consumption by the brain (3.8 ± 1.7 mg/day) [44]. However, loss of DHA in pathological states or due to nutritional deficiency of omega-3 FAs may severely impair neurovascular integrity and have far-reaching implications on normal brain function [36].
