MAJORITY OF THE HUMAN BRAIN CONSISTS OF FAT
The cell membrane is a thin, layered
sheet that separates the cell from the world outside. Cell membranes
are a two-molecule layer (bilayer) of phospholipid.
Almost 60% of the brain’s solid mass
is constituted of phospholipids, which contain fatty acids and have an
important role in cellular signaling. The other part of the brains
consists of 30% protein. In conclusion, the majority of the human brain
consists of fat.

The problem that arises is about a fifth
of that fat cannot be established by the body. Therefore, people have
to acquire it from their diet.

Can J Psychiatry. 2003
Apr;48(3):195-203.
Essential fatty acids and the
brain.
Haag
M.
Department of Physiology,
University of Pretoria, PO Box 2034, Pretoria 0001, South Africa.
mhaag@medic.up.ac.za
OBJECTIVE: To review the role of
essential fatty acids in brain membrane function and in the genesis
of psychiatric disease. METHOD: Medline databases were searched for
published articles with links among the following key words:
essential fatty acids, omega-3 fatty acids, docosahexanoic acid,
eicosapentanoic acid, arachidonic acid, neurotransmission,
phospholipase A2, depression, schizophrenia, mental performance,
attention-deficit hyperactivity disorder, and Alzheimer's disease.
Biochemistry textbooks were consulted on the role of fatty acids in
membrane function, neurotransmission, and eicosanoid formation. The
3-dimensional structures of fatty acids were obtained from the Web
site of the Biochemistry Department, University of Arizona (2001).
RESULTS: The fatty acid composition of neuronal cell membrane
phospholipids reflects their intake in the diet. The degree of a
fatty acid's desaturation determines its 3-dimensional structure and,
thus, membrane fluidity and function. The ratio between omega-3 and
omega-6 polyunsaturated fatty acids (PUFAs), in particular,
influences various aspects of serotoninergic and catecholaminergic
neurotransmission, as shown by studies in animal models.
Phospholipase A2 (PLA2) hydrolyzes fatty acids from membrane
phospholipids: liberated omega-6 PUFAs are metabolized to
prostaglandins with a higher inflammatory potential, compared with
those generated from the omega-3 family. Thus the activity of PLA2
coupled with membrane fatty acid composition may play a central role
in the development of neuronal dysfunction. Intervention trials in
human subjects show that omega-3 fatty acids have possible positive
effects in the treatment of various psychiatric disorders, but more
data are needed to make conclusive directives in this regard.
CONCLUSION: The ratio of membrane omega-3 to omega-6 PUFAs can be
modulated by dietary intake. This ratio influences neurotransmission
and prostaglandin formation, processes that are vital in the
maintenance of normal brain function.
PMID: 12728744 [PubMed - indexed for
MEDLINE]
FASEB
J. 1992 May;6(8):2530-6.
Biochemistry and physiology of n-3
fatty acids.
Lands
WE.
Department of Biochemistry, University
of Illinois, Chicago 60612.
Considering the n-3 fatty acids to be
partial agonists relative to n-6 fatty acids helps consolidate into a
unified interpretation the many diverse reports and controversies on
the actions of these two types of essential fatty acids. Some
research reports illustrate the similarities between these two types
and some emphasize the differences, leaving readers to evaluate the
status of n-3 fatty acids from a viewpoint that is conceptually
similar to regarding a glass of water as half empty or half full.
Both n-3 and n-6 types of fatty acids must be obtained through the
diet because they are not synthesized de novo by vertebrates. Both
types can support important physiological and developmental
processes, can form eicosanoids (prostaglandins, leukotrienes,
lipoxins, etc.), can be esterified to and hydrolyzed from tissue
glycerolipids, and can be metabolically elongated and desaturated to
a variety of highly unsaturated fatty acids. However, some
nonesterified n-6 acids are vigorously converted to potent n-6
eicosanoids that exert intense agonist actions at eicosanoid
receptors, whereas the n-3 acids less vigorously form n-3 eicosanoids
that often produce less intense (partial) actions. Because both types
owe their presence in vertebrate tissues to dietary intake, important
physiological consequences follow the inadvertent selection of
different average daily dietary supplies of these two types of
polyunsaturated fatty acids.
PMID: 1592205 [PubMed - indexed for
MEDLINE]
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