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DHA Supports Brain Development and Protects Neurological Function
By Russell L. Blaylock, MD
One of the major building blocks of the brain, the omega-3 fatty acid docosahexaenoic acid
(DHA) is critical for optimal brain health and function at all ages of life. Researchers are now
finding that DHA provides brain-boosting benefits in infants and aging adults.
Recognizing DHA’s crucial role in neurological and visual development in infants,
manufacturers are rushing to incorporate DHA into infant formulas and baby foods. Similarly,
adults seeking to stave off psychiatric and neurological ailments such as depression, posttraumatic
stress disorder, and Alzheimer’s disease are now paying careful attention to their
DHA intake.Here, we’ll discuss DHA’s integral role in ensuring optimal cognitive and neurological health.
MULTIPLE BENEFITS OF OMEGA-3 OILS
Most scientists and medical authorities agree that a higher intake of omega-3 oils is important for good health. This is based on
a large number of well-conducted studies in humans and animals, which have shown that omega-3 oils improve brain function,
decrease inflammation, reduce the incidence of fatal heart attacks and ischemic strokes, improve the outcome of autoimmune
diseases, and improve vision.
Of particular interest are the beneficial effects of omega-3 oils on neurological function and brain protection. For instance, a
number of studies have shown that higher intakes of omega-3 oils significantly reduce the incidence of Alzheimer’s disease as
well as vascular dementia, and improve quality of life and memory in those affected by dementia.
Although there is general agreement about the health benefits of omega-3 oils, few appreciate the differences in their various
components called eico-sapentaenoic acid (EPA) and docosahexaeonic acid (DHA). These two components make up the bulk of
the omega-3 oils. The ratio of EPA and DHA can vary considerably in commercial products, however, most of which have much
higher concentrations of EPA, mainly because it is less expensive to manufacture and has a less fishy odor than DHA. Yet,
studies have shown that most of the neurological benefits of omega-3 oils are derived from the DHA component rather than the
EPA component.
In both the Chicago and Rotterdam studies, researchers found a 60% reduction in the incidence of
Alzheimer’s disease in those eating at least one fish-containing meal a week. In the Chicago study,
DHA exerted a strong protective effect, which was not seen with EPA. Furthermore, this study
found that intake of the plant-derived omega-3 fatty acid, alpha-linolenic acid, was associated with a
reduction in the risk of Alzheimer’s disease in subjects carrying the APOE4 gene, which is a
powerful indicator of the disease.
People with Alzheimer’s disease have dramatically lower levels of DHA in the neurons of their hippocampus,
an area of the brain severely affected in the disease. This area is vital to creating recent
memories (so-called working memory or declarative memory). Prasad and co-workers from the
University of Kentucky found that phospholipids such as phosphatidyl-ethanolamine (PE), which
normally contain the highest levels of DHA, are severely depleted in those regions of the brain most
affected by Alzheimer’s disease.
DHA supplementation not only improves memory in cases of Alzheimer’s disease but has also been
shown to improve age-related memory loss as well. Animal studies have shown that DHAsupplemented
diets can counteract learning difficulties when soluble amyloid-beta (the most injurious
form of Alzheimer’s-associated amyloid) is infused into the animals’ brains.
Animal studies, both in mice and non-human primates, also show that DHA-depleted diets impair
learning and memory, and that re-feeding DHA-containing diets reverses these impairments.
Feeding rats diets high in DHA improves both working memory (very short-term memory) and reference
memory (longer-term) in both old and young animals.
Reisbick and co-workers at the Oregon Health Sciences University found that rhesus monkeys fed a
long-term omega-3-deficient diet began to show stereotyped behaviors during early life. These are the
type of repetitive behaviors seen with social deprivation and autism.
Clearly, omega-3 oils such as DHA play essential roles in learning, memory, and behavior. Next, we’ll look at their role in
supporting nervous system development.
DHA AND BRAIN DEVELOPMENT
A growing number of studies in both human infants and animals are showing a strong correlation between the intake of omega-3
oils, especially DHA, and cognitive function, visual acuity, and overall brain development. In the human infant, brain
development undergoes its most rapid and complex growth during the last trimester of pregnancy and the first two years after
birth. This means that during this period the child’s eventual neurological development is highly dependent on its dietary intake of essential
nutrients, especially omega-3 oils.
Because the fetal and infant brain is unable to convert enough alpha-linolenic oil (an omega-3 oil found in some plant oils) into
DHA, the baby almost totally depends on its mother for its supply. There is good
evidence that the placenta selectively takes up DHA so as to ensure an adequate supply for the growing baby.17,18 Some 70% of
energy supply during fetal development is devoted to brain development, and lipids make up 50 to 60% of the structure of the
brain, with DHA making up 30% of the brain and 50% of the retina’s structure. However, since the baby depends on the mother
for its supply of DHA, omega-3 deficiencies in the mother can lead to increases in DHA deficiency in the infant brain with each
successive birth. Studies have shown that brain DHA deficiency is limited to about 30% with the first generation, but by the third
generation, brain DHA levels can fall by as much as 85%.
The average DHA and EPA intake combined in the USA is about 100-200 mg/day, far below the 650 mg of DHA plus EPA that
experts recommend for healthy individuals.20 Furthermore, it has been shown that after birth, DHA levels fall between the ages of
6 and 12 months mostly due to low DHA content in most baby foods and formulas, which can have a profound effect on
postnatal brain development. A study that measured the impact of DHA on visual development in 6-month-old infants found that
retinal and visual cortex maturation was greatly improved in infants receiving DHA-enriched egg yolk versus control infants who
were deficient in DHA. In fact, the researchers found that even in breast-fed infants, DHA levels fell, whereas levels rose by 34%
in the supplemented infants.
In developing babies, higher levels of DHA levels are needed for the growth of neuronal cells than other brain structures.22 The
composition of the membranes of neural cells is under constant reconstruction, and can change drastically with changes in diet.
It has been shown that while other fatty acids plateau at birth, DHA levels actually double, mainly during periods of intense nerve
cell development, that is, during intense brain growth.
Overwhelming evidence for the benefits of DHA comes from a recent review of some 50 studies, which concluded that higher DHA in babies’
diets translates into better brain function, especially for cognitive and visual function. Further evidence that DHA may promote healthy nervous
system development comes from a recent study in which researchers divided 53 normal, healthy infants into those exclusively breast-fed and
those exclusively bottle-fed with a formula containing no DHA. Using assessments of visual, auditory, and sensory perception, they found
definite abnormalities in all three tests in the bottle-fed babies at one year of age.
A devastating consequence of low DHA status is its impact on the development of neurological abnormalities. In another study,
researchers measured DHA, essential fatty acids, trans fatty acids, and arachidonic acid levels in the umbilical artery and vein of
infants. They found that infants with neurological abnormalities at birth had significantly lower levels of arachidonic acid and DHA and higher
trans fatty acid levels.25 In contrast, infants with higher arachidonic acid, DHA, and essential fatty acid levels had
more normal neurological function. Editor’s note: While excess levels of arachidonic acid contribute to chronic inflammation in
aging humans, arachidonic acid is a critical building block to developing brains.
In a further test of cognitive development in infancy, researchers found that maternal and fetal DHA levels measured at birth
correlated with attention and distractibility at 12 and 18 months, with those having higher DHA levels fairing better than those with low levels. It
is also interesting to note that DHA plays a major role in muscle function and coordination in developing infants. A recent study using newborn
baboons revealed that the highest levels of DHA are found in the motor control areas of the brain,
which also play a major role in memory, social development, and behavior.
So we see that adequate DHA in the mother’s diet is critical for normal brain development in her babies, and that with the first
baby, her DHA level will fall even more because the placenta will preferentially extract the mother’s DHA for the baby. This means
that subsequent babies will have even lower DHA levels as the mother’s DHA is further depleted.
The big question is, can developmental problems triggered by low DHA levels be reversed? The evidence seems to indicate, yes.
For example, in one study, rats fed low-DHA diets for three generations from birth (producing severe deficiencies in brain DHA
levels) and then fed a DHA-enhanced diet for six weeks achieved the same level on testing of spatial learning as animals
maintained on an omega-3-adequate diet for three generations. A DHA-enriched diet for less than six weeks had no effect.
However, the rate of recovery of brain DHA varies among studies, depending on the experimental animal model and other
variables. In another study, rat pups that were fed DHA-depleted diets for two generations followed by an omega-3-containing diet beginning at
15 days after birth began to regain DHA in essential brain structures within one day, but full recovery took one
month. This slow recovery in rats was confirmed by other scientists. In the rhesus monkey, recovery of brain DHA can take
as long as 12 weeks.
In addition, the brain recovers its lost DHA slower than peripheral tissues. In one study, the rate of recovery of brain DHA went
from 19% at one week, to 35% at two weeks, and to 80% at eight weeks in rats. In the retina, which has an even higher DHA
content than the brain, recovery was faster than the brain, reaching 72% at four weeks, and was fully recovered at eight weeks.32
Recovery of DHA by the adult brain, however, is slower and less complete than the infant brain.
DHA AND THE ADULT BRAIN
While DHA is essential for the proper development of the infant brain, it also plays a vital role in the ongoing structure and
function of the adult brain. It is a component of several important phospholipids in the brain, with the highest levels of DHA being
found in phosphatidylethanolamine (PE) and phosphatidyl-serine Lower levels exist in phosphatidyl-cholines (PC).
Structurally, DHA comprises 22 carbons and six double bonds, making it the most unsaturated fatty acid in cell membranes and
an important ingredient in increasing the fluidity of cell membranes.
Changing the fluidity of cell membranes alters their physical properties, such as permeability and protein activity. This change
can drastically alter cell signaling and plays a major role in increasing membrane permeability of cancer cells, making them more
susceptible to immunologic and chemothera-peutic killing EPA, however, has much less effect on membrane fluidity than
DHA It has also been shown that a greater incorporation of DHA into cell membranes results in dramatically less susceptibility to lipid
peroxidation and oxidative stress in cells, especially neurons.
Although many view the brain as a stable structure that changes little after adolescence, it is in fact always in a state of flux, not
only by forming millions of new nerve connections, but also by replacing and altering its biochemical makeup, especially
membrane lipids. Connected with this constant turnover of brain lipids are the phospholipase enzymes, which can release
arachidonic acid and DHA from the cell membrane. Dietary changes can therefore drastically alter brain lipids, which can
significantly alter brain function, even worsening neuropsychiatric disorders.
Furthermore, there is evidence that as we age, the distribution of DHA in the brain changes. For example, during infancy the
highest levels are found in the striatum (associated with motor control) and are lower in the hypothalamus (linking the nervous
and endocrine systems) and hippocampus (associated with memory). In adults, the highest levels are in the cortex (essential to
cognition) and lowest in the medulla (crucial for autonomic function). With aging, the highest levels are in the cortex and
cerebellum (involved in motor control). An example of this regional specificity was seen in a recent study when scientists
restored dietary DHA to rats that had been deprived of the nutrient. They found that all areas of brain DHA were restored after 12
weeks, except for the medulla, which recovered only 62% of its DHA. These findings therefore provide plentiful evidence that
consuming enough DHA may be essential for upkeep of the adult brain.
DHA AND CELL SIGNALING
In the past, a lot of attention has been paid to the effects of omega-3 oils on membrane properties, which are very important to
the brain’s healthy functioning. After all, membranes regulate entry into the cell as well as control receptor function, which
facilitates cellular communication. More recently, however, researchers have discovered that omega-3 oils, especially the DHA
component, also affect cell signaling.

Quality Nutritional Supplements
Forestnaturals recommend NeuroKrill, the
most advanced formula that contains DHA
and EPA.
A scientific formula that provides original
and quality ingredients.
NeuroKrill
Krill Oil Plus DHA-conjugated Phosphatidylserine to support
Neurological Function†
DESCRIPTION
NeuroKrill, provided by Douglas Laboratories, is a novel formula designed to provide essential nutrients for neurological health and mental
functioning, including those processes involved in normal memory retention, mental focus and clarity†. The liquid filled two piece capsules
are made from fish based gelatin, making this product suitable for those
wishing to avoid bovine products.
FUNCTIONS
The maintenance of optimal neurological health and mental functioning requires a regular intake of essential nutrients including omega-3 fatty
acids, phospholipids and antioxidants. NeuroKrill has been specially formulated to supply these crucial nutrients from unique sources
including krill oil. Krill oil, derived from tiny crustaceans found in the
world’s oceans, is a source of essential omega-3 fatty acids, EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). EPA is the
direct precursor for the prostaglandins E1 and E3, which play important roles in supporting the body’s normal processes. DHA is important
for the structural integrity of neuronal membranes, essential for brain
and visual development and is vital throughout fetal brain growth to support the formation of the retina and visual cortex. Studies have shown
that DHA, along with EPA may play an important role in neurological health. When present in the brain, DHA is found mostly attached
(conjugated) to phospholipids including phosphatidylserine. and is the major acidic phospholipid component in the membranes of the brain.
Membranes are the essential functions of cellular communication and hormonal signal transduction. Nerve cells, in
particular, depend on healthy membrane function for normal neurotransmitter metabolism and nerve signal transmission. The fundamental
function of PS is to help maintain proper membrane fluidity, which has major implications on most membrane functions. NeuroKrill is unique
among other neurological supplements as it provides DHA-conjugated
phosphatidylserine, which mimics the natural chemical structure of PS found in the brain. Supplementation with this natural structure may
help increase the availability of DHA to the brain and thus provide greater neurological support. DHAconjugated phosphatidylserine is
clinically validated, as both animal and human studies indicate its
valuable roles in supporting optimum cognitive function and normal memory retention. NeuroKrill also supplies astaxanthin, a natural
carotenoid and powerful antioxidant, that can help protect cells from oxidative and free radical damage.
INDICATIONS
NeuroKrill may be a useful dietary supplement for
individuals wishing to support normal neurological
structure and function.
FORMULA(#200241)
1 Caplique™ Contains:
Ultra Pure Krill Oil(shellfish) ......................500 mg
Providing:
Phospholipids 195 mg
EPA [eicosapentaenoic acid] ...................75 mg
DHA [docosahexaenoic acid] ..................40 mg
Phosphatidylserine .......................................100 mg
(including DHA-conjugated phosphatidylserine)
Astaxanthin esters ........................................750 mcg
(as astaxanthin)
Other ingredients: Capsule (gelatin, from fish) and
olive oil
Contains: Soy