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Against survival of the fittest / The role of fish intake and lacustrine food in brain evolution
Insufficiency and dangers of high linoleic acid (from plants) vs DHA, EPA, ARA (from fish)
Linoleic acid is associated with lower long-chain n–6 and n–3 fatty acids in red blood cell lipids of Canadian pregnant women
Am J Clin Nutr 91: 23-31, 2010. First published November 18, 2009; doi:10.3945/ajcn.2009.28206 American Journal of Clinical Nutrition, doi:10.3945/ajcn.2009.28206 Linoleic acid is associated with lower long-chain n–6 and n–3 fatty acids in red blood cell lipids of Canadian pregnant women1,2,3
Russell W Friesen and Sheila M Innis
Background: Arachidonic (ARA), eicosapentaenoic (EPA), and docosahexaenoic (DHA) acids are important in membrane glycerophospholipids. Higher maternal blood ARA, EPA, and DHA concentrations in gestation are associated with higher maternal-to-fetal transfer of ARA, EPA, and DHA, respectively, which emphasizes the importance of maternal fatty acid status in gestation. As in the brain, red blood cell (RBC) ethanolamine phosphoglycerides (EPGs) are high in plasmalogen, ARA, and DHA.
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Conclusions: Membrane fatty acids are influenced by the amount and balance of fatty acid substrates. Our results suggest the competitive interaction of LA with ARA, EPA, and DHA, with no evidence that higher LA increases ARA. Biochemical indicators to suggest that DHA is limiting are present in our population.
Evidence for the Unique Function of Docosahexaenoic Acid (DHA) During the Evolution of the Modern Hominid Brain
Crawford MA1, Bloom M2, Leigh Broadhurst C3, Schmidt WF3, Cunnane
SC4, Galli C5, Ghebremeskel K1, Linseisen F2., Lloyd-Smith J2 and
Parkington J6
Lipids 2000, 34: S39-S47
The African savanna ecosystem of the large mammals and primates was associated with a
dramatic decline in relative brain capacity. This reduction happened to be associated with a
decline in docosahexaenoic acid (DHA) from the food chain. DHA is required for brain
structures and growth. The biochemistry implies that the expansion of the human brain
required a plentiful source of preformed DHA. The richest source of DHA is the marine
food chain while the savannah environment offers very little of it. Consequently H.
sapiens could not have evolved on the savannahs. Recent fossil evidence indicates that the
lacustrine and marine food chain was being extensively exploited at the time cerebral
expansion took place and suggests the alternative that the transition from the archaic to
modern humans took place at the land/water interface.
Contemporary data on tropical lake shore dwellers reaffirms the above view.
Lacustrine habitats provide nutritional support for the vascular system, the development of
which would have been a prerequisite for cerebral expansion. Both arachidonic acid (AA)
and DHA would have been freely available from such habitats providing the double
stimulus of preformed acyl components for the developing blood vessels and brain.
The ω3 docosapentaenoic acid precursor (ω3DPA) was the major ω3 metabolite in
the savanna mammals. Despite this abundance, neither it or the corresponding ω6DPA
were used for the photoreceptor nor the synapse. A substantial difference between DHA
and other fatty acids is required to explain this high specificity. Studies on fluidity and
other mechanical features of cell membranes have not revealed a difference of such
magnitude between even α-linolenic acid (LNA) and DHA sufficient to explain the
exclusive use of DHA. We suggest that the evolution of the large human brain depended
on a rich source of DHA from the land/water interface. We review a number of proposals
for the possible influence of DHA on physical properties of the brain that are essential for
its function.
