**6. Effects on brain functions**

The importance of fatty acids of vegetable origin in neural development, aging, and neurodegeneration has been addressed in several studies. The brain is an organ rich in phospholipids, which make up about 25% of its dry weight [93]. Some of these fatty acids participate in the structure, biochemistry, physiology, and consequently of the cerebral function, being necessary to maintain, under normal conditions, the cellular membranes, increasing their fluidity and functionality. They also aid in the nerve impulses transmission, reinforcing the importance of the adequate consumption of these lipids to benefit patients with neurological diseases [94, 95].

The consumption of PFAs is related to the reduction, prevention, and nonpharmacological treatment of some neurological diseases [96, 97]. Some studies show how eating habits can affect the brain development by making a comparison between the "Mediterranean diet" and the "western diet," for example. Whereas the Mediterranean diet is rich in long-chain PFAs derived from the combination of fruits, vegetables, cereals, olive oil, and other foods, the western diet is characterized by an increase in the consumption of SFAs and transfats due to the introduction of highly processed foods [98, 99]. Experimental data relate these dietary components

to neurological, neurodegenerative, and psychiatric disorders, since diets with high cholesterol rates increase the risk of developing such diseases, whereas diets with low saturated-fat intake reduce the risk of dementia [100–102], confirming the important role of diet in pathological mechanisms related to the brain.

The hypothesis that diet-induced changes affect brain circulation may be linked to changes in brain structure [103, 104]. The fatty acid content may affect the production and function of dopamine and serotonin [105], since omega-series fatty acids are fundamental for the maintenance of dopaminergic function in the brain, whereas irregularities of these fatty acids can interfere in the function of the dopaminergic receptors [104]. Healthy aging of humans on a regular diet was associated with neuroprotective properties, such as increased volume of the cortex's gray matter, higher total brain volume, and less white matter hyperintensities (lesions) [106], whereas high-energy transfat diets are associated with increased brain atrophy, and reduced total brain volume and numbers of neurons [107].

Adequate dietary intake of fatty acids or their precursors is also important during the perinatal period (before and after the baby's birth), since to ensure the normal development of the brain, newborns need more lipids than adults do. They are essential for fetal growth and development, and for neurological, behavioral, and learning functions [108–110]. Therefore, insufficient supplementation during early life may also aid in the development of diseases related to poor brain development, such as coordination disorder, dyspraxia (neurological motor dysfunction), and attention-deficit/hyperactivity disorder [109]. And the ingestion of fatty acids, mainly of the ω-3 type, positively affects the functioning and development throughout life, increasing cognitive functionality, such as learning, memory, and attention [110, 111].
