DHA is a Building Block for the Brain
prepared for Nu-Mega Ingredients
by
Dr Nadia Attar-Bashi and
Prof Andrew Sinclair
February 2004
Dr Nadia Attar-Bashi has a PhD in Food Science from RMIT University. Her research interests
during the PhD program included the role of alpha-linolenic acid in humans and animals and
studies on omega-3 fatty acids and prostate cancer.
Dr Andrew Sinclair is a Professor of Food Science at RMIT University. His research interests
include functional food ingredients including fats/oils, polyphenols, anti-oxidants, basic research
on the role of omega-3 fatty acids brain function in animals, food composition and dietary studies
on a range of fat soluble compounds.
DHA and brain
Abstract
Docosahexaenoic acid (DHA) is a long chain omega-3 fatty acid derived from an essential
nutrient (alpha-linolenic acid) and is found especially in high concentrations in brain grey matter
(neuronal and synaptosomal membranes) where it is the building block of the membrane
glycerophospholipids. All mammals have a high proportion of DHA in the brain grey matter
glycerophospholipids which suggests that DHA is essential for normal brain development and
function. Reductions of brain DHA levels by diet manipulation have been shown to affect many
processes in the brain (olfaction, audition, visual function, memory, learning and gene
expression). Reductions of brain DHA levels as a result of a peroxisomal deficiency disorder of
infants leads to severe neurological effects which are partially restored by provision of DHA.
Provision of DHA to the diet of premature infants restores visual and cognitive development to
that of premature infants fed exclusively on breast milk. Preliminary data suggests a similar need
for DHA in term infants. We conclude that DHA is essential for the normal function of the
mammalian brain and could be regarded as a building block for the brain, in much the same way
that calcium is a building block for bones.
1.2 What is DHA?
DHA is a fatty acid with 22 carbon atoms and 6 cis double bonds (all-cis-4, 7, 10, 13, 16, 19docosahexaenoic acid) whose structure is shown in Figure 1. DHA is found in high proportions in
membrane glycerophospholipids in the brain, retina and sperm of humans and animals (Figure 2
shows a diagrammatic representation of the location of glycerophospholipids (GPL) and their
fatty acids in membranes). DHA is also found in high concentrations in many species of marine
algae.
DHA can be made in mammals from alpha-linolenic acid (ALA), which is an essential fatty acid,
however there is some dispute about how effective this process is in humans (Sinclair et al 2002).
The other essential fatty acid is linoleic acid (LA) and both ALA and LA were discovered in the
1930s (Burr and Burr 1930). LA is the parent or precursor for the omega-6 series of PUFA, with
Page 2
DHA and brain
arachidonic acid (AA) being the other main omega-6 PUFA. ALA is the parent fatty acid for the
omega-3 series of PUFA, with eicosapentaenoic acid (EPA) and DHA being the other two main
members. All fatty acids in the LA (omega-6 or n-6) PUFA family have their first double bond 6
carbons from the terminal methyl end of the molecule. All fatty acids in the ALA (omega-3 or n3) PUFA family have their first double bond 3 carbons from the methyl end. The essential fatty
acids are like vitamins, in that they must be obtained from the diet. The reason for their
essentiality is that mammals, unlike plants, lack the enzymes to insert double bonds in 18-carbon
PUFA between the methyl end and the middle of the molecule.
1.3 Metabolism of ALA to DHA in mammals
The pathway of conversion of ALA to EPA (20:5n-3), 22:5n-3 (docosapentaenoic acid) and
DHA involves seven different steps of which three are desaturases, three are chain elongations
and one is a chain shortening reaction (Figure 3) (Brenna 2002, Voss et al 1991). This pathway
takes place mainly in the endoplasmic reticulum but the final chain shortening step involves
peroxisomal oxidation of 24:6n-3 (tetracosahexaenoic acid) to DHA (Moore et al 1995, Voss et
al 1991). An important issue is whether dietary ALA can supply tissues with all the EPA, 22:5n3 and DHA needed for optimal function or whether there are some tissues that might require a
dietary supply of EPA, 22:5n-3 and DHA. Studies in guinea pigs and primates have shown that
while dietary ALA can lead to high levels of DHA in neural tissue, it takes approx. ten times as
much ALA, on a gram for gram basis, compared with DHA to achieve the same level of neural
DHA (Abedin et al 1999, Sinclair et al 2002). One reason for this apparent inefficiency is that
ALA is extensively diverted to other pathways including beta-oxidation for energy production.
1.4 Factors which inhibit DHA synthesis
[a] The amount of LA in the diet influences DHA levels
LA and ALA compete for the same enzyme (delta-6 desaturase) to be metabolised to longer
chain PUFA such as AA (in the case of LA as substrate) and EPA and DHA (in the case of ALA
as substrate) (Figure 3). Typically, diets with a high level of LA relative to ALA lead to minimal
production of metabolites from ALA (Li et al 1999). Diets rich in LA decrease the expression of
Page 3
DHA and brain
the hepatic delta-6 desaturase compared with a diet rich in oleic acid, which also presumably
reduces the possibility of conversion of ALA to 18:4n-3 and 24:5n-3 to 24:6n-3 (Cho et al 1999).
The optimal ratio of LA to ALA is subject to considerable discussion and it may be as low as 1:1.
Based on the data that LA reduces the delta-6 desaturase levels (Cho et al 1999), an obvious
mechanism to promote EPA and DHA synthesis from ALA would be to reduce the dietary LA
level at the same time as increasing the ALA level. This strategy has been used successfully to
promote synthesis of EPA and DHA from ALA in human dietary studies (Mantzioris et al 1994)
and rat studies (O’Dea et al 1988).
[b] The importance of peroxisomes to DHA synthesis
The inherited disorder known as Zellwegger’s syndrome is one where patients lack peroxisomes
and therefore they cannot synthesise DHA since the final step in the synthesis of DHA involves
the peroxisomes (Martinez et al 2000). In children with this disease the levels of DHA in the
nervous system are extremely low and the disease results in early death (Martinez et al 2000).
Feeding these patients with a source of DHA increases tissue DHA levels and increases the life
span of the individuals (Martinez 2001).
[c] Effect of alcohol on DHA levels
It has been reported that primates and cats fed diets containing alcohol have reduced levels of
DHA in neural tissue (Pawlosky and Salem 1995, Pawlosky et al 2001). The mechanism is
thought to be due to accelerated breakdown of DHA.
2. Where is DHA distributed in the body?
2.1 DHA is present in the brain and retina
The brain contains the second highest concentration of lipids in the body, after adipose tissue,
with 36-60% of the nervous tissue being lipids (Documenta Geigy 1970). The lipids in brain are
complex lipids and include GPL, sphingolipids (sphingomyelin and cerebrosides), gangliosides,
and cholesterol with little or no triglycerides and cholesterol esters (Sastry 1985). Brain GPL
contains a high proportion of polyunsaturated fatty acids (PUFA), mainly DHA, AA and 22:4n-6,
Page 4
DHA and brain
with very small amounts of ALA and LA (Table 1). The proportion of DHA in the GPL of brain
grey matter is higher than the white matter (Svennerholm 1968, Pullarkat and Reha 1978), with
phosphatidylethanolamine (PE) and phosphatidylserine (PS) containing the most DHA amongst
all the GPL. The DHA content of the adult cerebral cortex is approximately 3% of the dry weight
and 0.4% of the white matter (Svennerholm 1968). The omega-6 content (20:4n-6 plus 22:4n-6)
of the cerebral cortex is similar to that of the DHA level and in white matter there is a higher
proportion of omega-6 than omega-3 PUFA (Svennerholm 1968). The highest proportion of
DHA in membrane lipids is found in the disk membranes of the rod outer segments of
photoreceptor cells in the retina (Fliesler and Anderson 1983, Boesze-Battaglia and Albert 1989).
The structural lipids of the photoreceptor outer segment membranes are 80-90% GPL and 8-10%
cholesterol (Daemen 1973) and in the PE and PS fractions the proportion of DHA is up to 50 mol
% (Neuringer 1993). In the retina, some GPL contain two DHA molecules per mol of GPL (Lin
et al 1990). The outer segments of photoreceptor cells are highly specialized membranes and are
the site of the initiation of the process of vision (Neuringer 1993). It is believed that rhodopsin
molecules which are transmembrane receptors are surrounded by a ring of PS (rich in DHA) and
that the DHA plays a role as a molecular spring when light activates rhodopsin (Dratz & Holte
1993). Sperm flagella also contain a very high proportion of DHA in the GPL (Connor et al
1997).
2.2 DHA is present in other tissues in the body
DHA is also present in other tissue in the body but in lower proportions. For example, in the
guinea pig the proportion of DHA of all tissues except neural tissue was <0.5% of total tissue
fatty acids while in whole brain it was 6-7% of total fatty acids (Fu et al 2001). On a whole body
basis, the brain contained approximately 22-25% of the total DHA in the body, with
approximately 50% of the DHA being in the carcass (muscle and adipose tissue) (Figure 4).
2.3 Fatty acid composition of brain is constant across species
The fatty acid profile of brain grey matter PE from 30 different mammalian species (from the
mouse to the elephant and including humans) has a remarkably constant fatty acid composition
Page 5
DHA and brain
across species (Sinclair 1975a, Crawford et al 1976) (Table 1). In contrast, the fatty acid
composition of the muscle and liver PE fatty acids showed substantial variability between the
same 30 species. DHA was present in the brain lipids at the highest concentration compared with
other fatty acids (Sinclair 1975a, Crawford et al 1976).
The high levels of brain DHA in different mammalian species, led to early speculations that this
molecule was playing a crucial role in the nervous system. In the 1970’s, the omega-6 PUFA
were regarded as essential for humans and the omega-3 PUFA were only thought to be essential
for fish and other marine species. The first clue for a physiological role for omega-3 fatty acids in
mammals came when it was reported that dietary omega-3 PUFA fed to rats led to nearly double
the response of the retina to visual stimulation of rats compared with when omega-6 PUFA were
fed (Wheeler et al 1975).
3. DHA accretion in the brain
When rats are given an oral dose of radio-labelled DHA, 1.8% of the dose given can be found in
DHA in the brain. In contrast, when ALA is given, only approx. 0.03 % of the dose is found in
brain DHA (Sinclair 1975b). Figure 5 outlines the way in which DHA gets to the brain from the
diet.
3.1 Entry of fatty acids into the blood stream
The two main points where fatty acids enter the blood stream are the liver and the gastrointestinal
tract. DHA and AA are mostly made in the liver from their dietary precursors ALA and LA,
respectively. The conversion of ALA to DHA is believed to be limited in young healthy male
adults, compared with young women who are capable of some DHA synthesis (Burdge et al
2002, Burdge and Wooton 2002, Pawlosky et al 2003). DHA can also enter the blood by
consuming food naturally containing DHA (eg: fish, fish oils, eggs, liver) or foods fortified with
DHA-rich fish oils
3.2 Release of DHA from blood transport mechanisms
Page 6
DHA and brain
DHA is transported in the blood either in the form of triglycerides and GPL associated with
lipoproteins or as free fatty acids or lyso-phosphatidylcholine bound to albumin (Horrobin 1999;
Lagarde et al 2001). DHA can be released from the lipoprotein triglyceride by the action of
lipoprotein lipase in the endothelial cells of the capillaries of the brain and other tissues (Ben
Zeev et al 1990, Vilaro et al 1990, Nunez et al 1995). DHA can also be released from albumin by
diffusion, which depends on the concentration gradient created by fatty acid binding proteins in
the brain and other tissues (Horrobin 1999). Recent data suggest that approx. 55% of DHA in
human plasma is in the form of 2-lysophosphatidylcholine, mostly bound to albumin (Croset
2000) which together with free DHA bound to albumin can be a carrier of DHA to the brain
(Lagarde et al 2001).
The DHA bound to circulating plasma albumin can rapidly dissociate from the albumin as the
blood passes through the brain and approximately 5% is extracted by the brain.
The
incorporation of fatty acids into the brain is determined by the rate of esterification via acyl CoA
transferase (Rapoport 2003) (Figure 6). Once the CoA derivative is formed, it is used to acylate
1-lysophospholipids with a smaller proportion being lost through β-oxidation. The DHA is
released from the GPL by the action of various phospholipase A2 which exist in the brain, and
then it enters the unesterified brain DHA pool. This is thought to be largely located at the
synapse and is a pool which does not directly exchange with the DHA in plasma (Rapoport
2003). This pool is a precursor pool for conversion to eicosanoids.
3.3 Cellular uptake of DHA
DHA in the extracellular fluid is rapidly taken up into neural cells by transport mechanisms
involving fatty acid transporter proteins and by simple diffusion through the membranes (Robert
et al 1983, Spector and Yorek 1985, Thompson 1992). They are then available to be incorporated
into GPL. Some cells are neural cells capable of making DHA and AA in the brain from their
precursors ALA and LA, respectively. Within the brain cells, fatty acid trafficking is regulated
via at least three fatty acid binding proteins (FABP) and these play an important role in neuronal
development since some or all of them are strongly expressed when neuronal growth and
Page 7
DHA and brain
development are taking place in the brain (Owada et al 1996, Rousselot et al 1997, Utsunomiya et
al 1997, Balendiran et al 2000).
4. Where is DHA located in the brain?
There have been few systematic studies on the DHA content in different regions or cell types in
the brain. Early studies in rats showed that astrocytes and synaptosomes contain the highest
proportion of DHA, compared with neuronal cells (intermediate levels) and myelin (lowest
levels) (Bourre et al 1984). More recently, Carrie et al (2000) showed that the proportion of
DHA in eleven different regions of the rat brain varied from 7% of GPL fatty acids in the
pituitary gland to 22% in the frontal cortex.
5. What is the role of DHA in the brain and retina?
5.1 Evidence from animal studies
The classical way of studying the role of DHA in the brain has been to examine what happens in
animals fed diets lacking omega-3 PUFA. These studies have shown reductions in the level of
DHA in brain lipids on such diets. When there is a reduced level of DHA in the brain GPL,
many dramatic changes in brain function have been reported including changes in size of
neurons, changes in learning and memory, changes in the auditory and olfactory responses to
stimuli, changes in nerve growth factor levels and alterations in the level of 2arachidonylglycerol (a putative endogenous ligand for cannabinoid receptors) (Salem and Ward
1993, Greiner et al 1999, Bourre et al 1999, Umezawa et al 1999, Ahmad et al 2002a, Ahmad et
al 2002b, Ikemoto et al 2000, Moriguchi & Salem 2003, Watanabe et al 2003).
Various mechanisms have been suggested to account for these physiological changes in the brain
and retina, as reviewed recently by Kurlack and Stephenson (1999), Lauritzen et al (2001) and
Salem et al (2001). Mostly, the changes appear to be related to changes in membrane function,
Page 8
DHA and brain
however recent studies have shown that DHA can also influence gene expression in the brain. In
summary, DHA plays a crucial role in:
Membrane related events
•
membrane order (membrane fluidity) which can influence the function of membrane
receptors such as rhodopsin (Litman et al 2001, Feller et al 2002)
•
regulation of dopaminergic and serotoninergic neurotransmission (Zimmer et al 2000)
•
regulation of membrane-bound enzymes (Na/K-dependent ATP’ase) (Bowen and
Clandinin 2002)
•
signal transduction via effects on inositol phosphates, DAG and protein kinase C
(Vaidyanathan et al 1994)
•
Alteration of ion flux through voltage-gated K+ and Na+ channels (Seebungkert &
Lynch 2002, Leaf et al 2002).
Metabolic events
•
regulation of the synthesis of eicosanoids derived from arachidonic acid (Kurlack and
Stephenson 1999)
•
as a precursor of docosatrienes and 17S resolvins (novel anti-inflammatory mediators)
(Hong et al 2003)
Gene expression
•
regulation of gene expression of many different genes in rat brain in short and long-term
studies (De Urquiza et al 2000, Rojas et al 2002, Kitajka et al 2002, Barcelo-Coblijn et al
2003a&b, Puskas et al 2003 ). In the study by Kitajka et al (2002), the rats were fed
throughout life with either a vegetable oil (rich in ALA) or a fish oil (rich in EPA +
DHA). The control rats were fed a diet rich in linoleic acid (omega-6). There was an
increase in the brain DHA level in both test groups. cDNA microarray analysis showed
highly significant alterations in the expression of more than 100 genes in the brain
(approx equal number over- and under-expressed). Of interest was the fact that the ATPgenerating machinery of the brain responded to the dietary omega-3 PUFA most
Page 9
DHA and brain
intensively. The brain is known to exhibit a high metabolic rate and a high proportion of
this is used to maintain Na/K ATPase activity, which regulates ion flow resulting from
nerve transmission. Genes participating in signal transduction were also overexpressed,
almost to same extent, by both the ALA-rich and EPA+DHA-rich diet. Also of interest
is that genes encoding for synuclein alpha and gamma were overexpressed. Synucleins
plays a role in neural plasticity, are associated with synaptosomes and are related to
learning in the brains of songbirds (George et al 1995).
Cellular events
•
regulation of phosphatidyl serine levels (Garcia et al 1998) which appears to be involved
in the protection of neural cells from apoptotic death (Akbar and Kim 2002)
•
stimulation of neurite outgrowth in PC-12 brain or neuron cells (Ikemoto et al 1997,
Martin 1998)
•
selective accumulation of DHA by synaptic growth cones during neuronal development
(Ikemoto et al 1997, Martin 1998)
•
regulation of neuron size (Ahmad et al 2002a, Ahmad et al 2002b)
•
regulation of nerve growth factor (Ikemoto et al 2000),
•
as a precursor of neuroprostanes (DHA oxidation products) (Roberts et al 1998, Fam et
al 2002).
Recently, DHA has been established as the precursor of a novel series of endogenous mediators
present in human blood, leukocytes, murine brain and human glial cells (Hong et al 2003). The
novel mediators are called docosatrienes (17S-hydroxy-containing docosanoids) and 17S series
resolvins, they are biosynthesised via enzymatic oxygenation and are potent regulators of both
leukocytes (reducing infiltration in vivo) and glial cells (blocking their cytokine production)
(Hong et al 2003). It is not known whether these bioactive mediators derived from DHA are
responsible for some of the beneficial actions reported following dietary supplementation with
DHA (Hong et al 2003).
DHA can also undergo non-enzymatic free-radical catalysed oxidation in the brain to form F 2 isoprostane-like compounds that are known as F 4 -neuroprostanes and highly reactive A/J-ring
Page 10
DHA and brain
neuroprostanes which may provide a marker of oxidative injury in the brain (Roberts et al 1998,
Fam et al 2002). These results suggest that oxidative stress is ongoing in the central nervous
system (Reich et al 2000, Fam et al 2002). Preliminary studies show significantly increased
levels of neuroprostanes in brain regions in Alzheimer’s patients (Reich et al 2001).
5.2 Nervous system in infants
There is a rapid increase in the weight of the human brain post-natally until the infant is about
two years old. Associated with this, there is a rapid accretion of DHA in the infant brain during
the first postnatal year (Martinez et al 1992) and it is thought that this DHA for brain growth is
largely derived from mothers’ milk. Breast milk contains DHA, and breast feeding provides at
least 49 mg of DHA to the infant each day depending on the DHA level in the mother’s milk
(Mitoulas et al 2003). It is known that this is influenced by diet but is usually in the range from
0.2 to 1.0 % of total milk fatty acids. DHA levels in human milk can increase rapidly (within 6
hours with a maximum at 24 hours) after lactating mothers consume marine oils rich in DHA
(Francois et al 1998).
Part of the unique function of DHA in the nervous system seems to be related to the synthesis of
GPL for the membranes needed for neurite elongation (Ikemoto et al 1997). During fetal
development, DHA is preferentially transported across the placenta into the fetal circulation
(Green et al 1998). The fetal brain is believed to be able to produce limited amount of DHA from
ALA and the liver may also be able to produce some DHA (Salem et al 1996), however it is
believed that this is not enough for optimal development (Horrocks and Yeo 1999). Premature
infants are born with deficits of DHA (Boehm et al 1996). Reduction in the supply of the
precursors for membrane growth may contribute to the fragility of the periventricular vascular
system and may be responsible for haemorrhage which is a risk for premature infants (Horrocks
and Yeo 1999).
Improved visual development has been reported for pre-term infants who were fed formulas
supplemented with DHA compared with no added DHA (Carlson et al 1992, Uauy et al 1994,
Carlson et al 1996). However, some studies found evidence of slower growth (Carlson et al 1992,
Carlson et al 1996, Ryan et al 1999). Subsequent studies with pre-term infants fed DHA and AA
Page 11
DHA and brain
showed there was enhanced visual and cognitive development with no adverse effects on growth
(Vanderhoof et al 1999, Vanderhoof et al 2000, Gibson & Macrides 2001, Innis et al 2002). In a
study of 14 controlled trials in term infants, Uauy et al (2003) concluded that there was a
significant relation between DHA intake and visual acuity measured at 4 months of age. It has
been argued that based on the rate of accretion of DHA into the human brain, there is a need to
supply DHA via breast milk or infant formula for at least the first 6 months of life (Cunnane et al
2000).
6. Do we get enough DHA?
It is generally regarded that many nations do not eat sufficient DHA. This is particularly true for
developed nations with a low reliance on fish consumption, such as Australia, UK, USA and
Canada. Where there have been recommendations for an adequate intake of long chain omega-3
PUFA (EPA plus DHA), the figure is of the order of 200 mg of these PUFA daily (Table 3). In
Australia, according to the 1995 Australian National Nutrition Survey, the average daily intake of
DHA in adults was 0.106g/day with the median intake being considerably lower at 0.015g/day
(Meyer et al 2003). In other words, Australians are not meeting their recommended daily intake
of DHA.
It is often asked whether we can obtain our DHA by synthesis from ALA. This issue has been
addressed earlier in this report. Recently, it has been suggested that with current intakes of ALA,
the likely DHA synthesis is of the order of 27 mg /day, also well below the recommended levels
(Salem et al 2003).
6.1 Recommended intake of DHA for adults and infants
Table 3 shows the international recommendations for DHA intake in adults and infants. It is
recommended that pregnant and nursing mothers increase their DHA intake and also that infants
need DHA either from breast milk or from infant formulas.
6.2 Intake of DHA in infants: breast milk versus infant formulas
Page 12
DHA and brain
Breast milk contains AA and DHA and until recently infant formulas did not. The mean amounts
of PUFA in human milk from Australian mothers across the first year of lactation have recently
been determined (mg/day) as LA (2380), ALA (194), AA (93), and DHA (59) (Mitoulas et al
2003). Recent technological developments, including a ready supply of AA and DHA, and
reliable mechanisms to protect these from oxidation during the manufacture and storage of dry
powder formulas, in a process known as microencapsulation (Yep et al 2002), have enabled
formula companies to add AA and DHA to pre-term and term formulas. In 2001, the U.S. Food
and Drug Administration and Health Canada joined the rest of the world in permitting the
addition of DHA and AA to infant formulas (Food and Drug Administration 2001).
7.0 Conclusions
This review presented evidence that DHA is a major fatty acid found in the brains in humans and
animals, especially in grey matter. In the cerebral cortex of humans, approx 3% of the dry weight
of the tissue is DHA. Evidence was presented that DHA has important structural, biochemical
(metabolic and gene expression) functions in the nervous system. From this review, we suggest
that it would be reasonable to conclude that DHA could be regarded as a building block for the
brain in humans of all ages (infants through to the elderly).
Page 13
DHA and brain
Figure 1: A two dimensional structure of docosahexaenoic acid. The first double bond in
docosahexaenoic acid occurs between carbons 3 and 4 from the methyl end. The position of the
first carbon of the first double bond identifies the omega-type (or n-X type) of the fatty acid.
DHA is an omega-3 (n-3) polyunsaturated fatty acid (PUFA).
Page 14
DHA and brain
Figure 2: Diagram of a membrane (adapted from Natural toxins research centre website,
http://ntri.tamuk.edu)
Page 15
DHA and brain
Linoleic Acid (18:2n-6)
α-Linolenic Acid (18:3n-3)
Δ-6 desaturase
18:3n-6
18:4n-3
Chain elongation
Hydroxy
Fatty Acid
20:3n-6
20:4n-3
Δ-5 desaturase
Eicosanoids
Leukotrienes
Arachidonic Acid (20:4n-6)
Eicosapentaenoic Acid (20:5n-3)
Eicosanoids,
Leukotrienes,
& Hydroxy
Fatty Acids
Chain elongation
22:4n-6
22:5n-3
Chain elongation
24:4n-6
24:5n-3
Δ-6 desaturase
24:5n-6
24:6n-3
Hydroxy Fatty
Acids
Docosahexaenoic Acid (22:6n-3)
A/J-ring
Neuroprostane
Chain shortening
(Peroxisomal oxidation)
22:5n-6
Docosatrienes &
17S-Resolvins
Figure 3: Metabolic steps involved in converting essential fatty acids into their longer chain
metabolites and their products.
Page 16
DHA level (% of whole body fatty acid content)
DHA and brain
70
60
50
40
High ALA diet
Low ALA diet
30
20
10
0
Carcass
(muscle+
bone)
Brain
Adipose
Liver
Skin+ fur
Figure 4: Distribution of DHA in different tissues in guinea pigs after been fed on diets high or
low in alpha-linolenic acid (data adapted from Fu et al, 2001).
Page 17
DHA and brain
Diet
LA and ALA
AA and DHA
Liver
Formation of
AA and DHA
in the liver
AA and DHA
Blood
AA and
DHA bound
albumin
AA and
DHA in
lipoproteins
Diffusion
Lipoprotein
lipase
Fatty acid transport
proteins
Blood-brain
barrier
Brain
Fatty acid binding proteins
Free fatty acid pool
AA and DHA
Acyltransferases
Phospholipase A 2
or
Phospholipase C
AA and DHA
Membrane PL
Figure 5: The routes whereby AA and DHA reach brain PL. Figure adapted from Horrobin 1999.
Page 18
DHA and brain
NPs covalently
binding to
proteins
Alteration of
protein function
GENE
EXPRESSION
Neuroprostanes
Cellular
function
Membrane
PL’s
H 2 C-O-CO-R 1
Non-enzymatic
oxidation
Lipoxygenase
Docosatrienes,
17S Resolvins
HETEs
PLA 2
2 HC-DHA
DHA
(synapse)
FABP
H 2 C-O-P-O-X
Acyl
Transferase
H 2 C-O-CO-R 1
R
DHA
(endoplasmic reticulum)
BBB
PLASMA
DHA-CoA
Acyl-CoA
synthetase
+
2H
C-OH
H 2 C-O-P-O-X
Lyso-PL
FABP
β-Oxidation
DHA
ALBUMIN – DHA
ALBUMIN – LYSOPC-DHA
Figure 6: Uptake and metabolism of DHA in the brain (Figure adapted from Rapoport 2003).
BBB = blood brain barrier, FABP = fatty acid binding protein
Page 19
DHA and brain
Table 1. Polyunsaturated fatty acids in ethanolamine phosphoglycerides of mammalian liver and
brain grey matter (mg/1000mg total fatty acids and aldehydes)
Fatty Acid
Brain
Liver
18:2n-6
Linoleic Acid
12 (3-24)a
120 (31-470)
20:3n-6
Dihomo-gammalinolenic Acid
7 (2-10)
11 (3-45)
20:4n-6
Arachidonic Acid
120 (89-150)
130 (41-210)
22:4n-6
Docosatetraenoic Acid
63 (42-80)
10 (1-56)
22:5n-6
Docosapentaenoic Acid
12 (2-29)
5 (1-14)
18:3n-3
Alpha-linolenic Acid
5 (1-10)
21 (1-54)
20:5n-3
Eicosapentaenoic Acid
6 (1-12)
23 (5-78)
22:5n-3
Docosapentaenoic Acid
7 (3-19)
54 (3-110)
22:6n-3
220 (160-290)
98 (2-220)
Docosahexaenoic Acid
a
Results are shown as the mean value and range for twenty-five species (Sinclair 1975a)
Page 20
DHA and brain
Table 2: DHA in different glycerophospholipid classes of brain grey and white matter
GPL class
PE
PS
PI
PC
Sphingolipids
% DHA in GPL class
Grey matter
29
31
4
2.6
trace
Data from Svennerholm, 1968.
Page 21
White matter
3
1
1.5
0.4
trace
DHA and brain
Table 3: International recommendation for EPA plus DHA intake in adults and infants
Organization
BNF
COMA
Eurodiet
Health Canada
Recommended intake of DHA Recommended intake of DHA
for adults
for infants
0.5% of total energy of 20mg/Kg body weight
EPA+DHA or 1.2g/day
0.2g/day of EPA and DHA
0.2g/day of EPA+DHA
0.05g/day-first trimester
0.16g/day-second trimester
0.25g/day-third trimester and
lactation
WHO
Workshop*
France-AFSSA
Preterm infants- 40mg/Kg body
weight of DHA
Term infants- 20mg/Kg body
weight of DHA
0.22g/day of DHA or 0.1% of
energy
Pregnant women-0.3g/day
Adult man-0.12g/day DHA
Adult woman-0.1g/day DHA
Pregnant and nursing woman0.25g/day DHA
Aged subject-0.1g/day DHA
Infant formula or diet-0.35% of
fatty acids
Nursing term and premature
infants-0.1 to 0.4% of total energy
DHA
HCN
Pregnant woman-0.02g/Kg/day
1-12months age-0.02g/Kg/day
BNF=British Nutrition Foundation
COMA=Committee on Medical aspects of Food Policy
WHO= World Health Organisation
* ISSFAL Workshop on the essentiality of and dietary reference intakes for omega-3 and omega6 fatty acids
HCN=Health Council of the Netherlands
Page 22
DHA and brain
References
Abedin L, Lien EL, Vingrys AJ, Sinclair AJ. (1999) The effects of dietary alpha-linolenic acid
compared with docosahexaenoic acid on brain, retina, liver, and heart in the guinea pig. Lipids.
34, 475-82
Ahmad, A., Moriguchi, T., and Salem Jr., N. (2002a) Decrease in neuron size in docosahexaenoic
acid-deficient brain. Ped. Neurol. 26:210-218.
Ahmad, A., Murthy, M., Greiner, R.S., Moriguchi, T. and Salem Jr., N. (2002b) A decrease in
cell size accompanies a loss of docosahexaenoate in the rat hippocampus. Nutr Neurosci. 5:103113.
Akbar, M. and Kim, H.Y. (2002) Protective effects of docosahexaenoic acid in staurosporineinduced apoptosis: involvement of phosphatidyl-3-kinase pathway. J. Neurochem. 82:655-665.
Balendiran GK, Schnutgen F, Scapin G, Borchers T, Xhong N, Lim K, Godbout R,
Spener F, Sacchettini JC. (2000) Crystal structure and thermodynamic analysis of human brain
fatty acid-binding protein. J Biol Chem. 275, 27045-54
Barcelo-Coblijn G, Kitajka K, Puskas LG et al (2003a) Gene Expression and Molecular
Composition of Phospholipids in Rat Brain in relation to Dietary n-6 to n-3 Fatty Acid Ratio
BBA 1632,72-79.
Barcelo-Coblijn G, Kitajka K, Puskas LG et al (2003b) Modification by DHA of Age-induced
Alterations in Gene Expression and Molecular Composition of Rat Brain Phospholipids PNAS
100, 11321-26
Ben-Zeev, O., Doolittle, M. H., Singh, N., Chang, C.H., Schotz, M.C. (1990) Synthesis and
regulation of lipoprotein lipase in the hippocampus. J. Lipid Res. 31: 1307-13.
Boehm, G., Borte, M., Bohles, H.J., Muller. H., Kohn. G., Moro, G. (1996) Docosahexaenoic and
arachidonic acid content of serum and red blood cell membrane phospholipids of preterm infants
fed breast milk, standard formula or formula supplemented with n-3 and n-6 long-chain
polyunsaturated fatty acids. Eur. J. Pediatr. 155: 410-6.
Boesze-Battaglia, K., Albert, A.D. (1989) Fatty acid composition of bovine rod outer segment
plasma membrane. Exp Eye Res. 49: 699-701.
Bourre JM, Pascal G, Durand G, Masson M, Dumont O, Piciotti M. (1984) Alterations in the
fatty acid composition of rat brain cells (neurons, astrocytes, and oligodendrocytes) and of
subcellular fractions (myelin and synaptosomes) induced by a diet devoid of n-3 fatty acid. J
Neurochem. 43, 342-8.
Bourre, J.M., Durand, G., Erre, J.P, and Aran, J.M. (1999) Changes in auditory brainstem
responses in alpha-linolenic acid deficiency as a function of age in rats. Audiology 38:13-18.
Page 23
DHA and brain
Bowen, R.A., and Clandinin M.T. (2002) Dietary low linolenic acid compared with
docosahexaenoic acid alter synaptic plasma membrane phospholipids fatty acid composition and
sodium-potassium ATPase kinetics in developing rats. J. Neurochem. 83:764-774.
Brenna, J.T. (2002) Efficiency of conversion of alpha-linolenic acid to long chain n-3 fatty acids
in man. Curr. Opin. Clin. Nutr. Metab. Care 5:127-132.
Burdge G.C, and Wooton S.A. (2002) Conversion of α−linolenic Acid to Eicosapentaenoic,
Docosapentaenoic and Docosahexaenoic Acids in Young Woman. Br. J. Nutr. 88:411-420.
Burdge, G.C., Jones, A.E, and Wooton, S.A. (2002) Eicosapentaenoic and Docosapentaenoic
Acids are the Principal Products of α−linolenic Acid Metabolism in Young Men. Br. J. Nutr.
88:355-363.
Burr, G.O., and Burr, M..M. (1930) On the nature and role of fatty acids essential in nutrition. J.
Biol. Chem. 86:587-621.
Carlson SE, Cooke RJ, Werkman SH, Tolley EA. (1992) First year growth of preterm infants fed
standard compared to marine oil n-3 supplemented formula. Lipids. 27, 901-7.
Carlson SE, Werkman SH, Tolley EA. (1996) Effect of long-chain n-3 fatty acid supplementation
on visual acuity and growth of preterm infants with and without bronchopulmonary dysplasia.
Am J Clin Nutr. 63, 687-97.
Carrie I, Clement M, de Javel D, Frances H, Bourre JM (2000) Specific phospholipid fatty acid
composition of brain regions in mice. Effects of n-3 polyunsaturated fatty acid deficiency and
phospholipid supplementation. J Lipid Res. 41, 465-72.
Cho, H.P., Nakamura, M.T., and Clarke, S.D. (1999a) Cloning, expression, and nutritional
regulation of the mammalian delta-6 desaturase. J. Biol. Chem. 274:471-477.
Connor WE, Lin DS, Neuringer M. (1997) Biochemical markers for puberty in the monkey testis:
desmosterol and docosahexaenoic acid. J. Clin. Endocrinol. Metab. 82: 1911-6.
Crawford, M.A, Casperd, N.M, and Sinclair, A.J. (1976) The long chain metabolites of linoleic
and linolenic acids in liver and brain in herbivoures and carnivores. Comp Biochem Physiol
54B:395-401.
Croset, M., Brossard, N., Polette, A., Lagarde, M. (2000) Characterization of plasma unsaturated
lysophosphatidylcholines in human and rat. Biochem J. 345: 61-7.
Cunnane SC, Francescutti V, Brenna JT, Crawford MA. (2000) Breast-fed infants achieve a
higher rate of brain and whole body docosahexaenoate accumulation than formula-fed infants not
consuming dietary docosahexaenoate. Lipids. 35, 105-11.
Daemen FJ. (1973) Vertebrate rod outer segment membranes. Biochim. Biophys. Acta 300: 25588.
Page 24
DHA and brain
De Urquiza, A.M., Liu, S., Sjoberg, M., Zetterstrom, R.H., Griffiths, W., Sjovall, J. and
Perlmann, T. (2000) Docosahexaenoic acid, a ligand for the retinoid X receptor in mouse brain.
Science 290:2140-2144.
Documenta Geigy, Scientific Tables, 7th Edition, Eds K Diem & C Lentner, Geigy
Pharmaceuticals, Maccasfield, UK 1970
Dratz EA and Holte LL (1993) The molecular spring model for the finction of DHA in Biological
Membranes, pp 122-127, EFA and Eicosanoids: Invited papers from the Third International
Conference, AOCS Press, Champaign, IL
Fam, S.S., Murphey, L.J., Terry, E.S., Zackert, W.E., Chen, Y., Gao, L., Pandalai, S., Milne,
G.L., Roberts, L.J., Porter, N.A., Montine, T.J., and Morrow, J.D. (2002) Formation of highly
reactive A-ring and J-ring isoprostane-like compounds (A4/J4-neuroprostanes) in vivo from
docosahexaenoic acid. J. Biol. Chem. 277:36076-84.
Feller, S.E., Gawrisch, K. and MacKerell, A.D. (2002) Polyunsaturated fatty acids in lipid
bilayers: instrinsic and environmental contributions to their unique physical properties. J. Am.
Chem. Soc. 124:318-326.
Fleisler, S.J., and Anderson, R.E. (1983) Chemistry and metabolism of lipids in the vertebrate
retina. Prog. Lipids Res. 22:79.
Food and Drug Administration 2001, www.cfsan.fda.gov/~rdb/opa-g080.html.
Francois, C.A., Connor, S.L., Wander, R.C., Connor, W.E. (1998) Acute effects of dietary fatty
acids on the fatty acids of human milk. Am. J. Clin. Nutr. 67: 301-8.
Fu, Z., Attar-Bashi, N.M., and Sinclair, A.J. (2001) 1-14C-linoleic acid distribution in various
tissue lipids of guinea pigs following an oral dose. Lipids 36:255-60.
Garcia, M.C., Ward, G., Ma, Y-C., Salem Jr., N. and Kim, H-Y. (1998) Effect of
docosahexaenoic acid on the synthesis of phosphatidylserine in rat brain microsomes and C6
glioma cells. J Neurochem 70:24-30.
George JM et al 1995 Characterisation of a novel protein regulated during the critical period for
song learning in the zebra finch Neuron 15,361-72.
Gibson, R.A., Makrides, M. (2001) Long-chain polyunsaturated fatty acids in breast milk: are
they essential? Adv. Exp. Med. Biol. 501: 375-83
Green, J.E., Greenberg, N.M., Ashendel, C.L., Barrett, J.C., Boone, C., Getzenbeerg, R.H.,
Henkin, J., Matusik, R., Janus, T.J., Scher, H.I. (1998) Work-group 3: transgenic and
reconstitution models of prostate cancer. Prostate 36:59-63.
Greiner, R.S, Moriguchi, T., Hutton, A., Slotnick, B.M., and Salem Jr., N. (1999) Rats with low
levels of brain docosahexaenoic acid show impaired performance in olfactory-based and spatial
learning tasks. Lipids 34:S239-S243.
Page 25
DHA and brain
Hong, S., Gronert, K., Devchand, P.R., Moussignac, R.L., and Serhan, C.N. (2003) Novel
Docosatrienes and 17S-Resolvins Generated from Docosahexaenoic Acid in Murine Brain,
Human Blood, and Glial Cells. Autocoids in inflammation. J. Biol. Chem. 278:14677-87.
Horrobin DF. (1999) Lipid metabolism, human evolution and schizophrenia. Prostaglandins
Leukot Essent Fatty Acids. 60, 431-7.
Horrocks, L.A., Yeo, Y.K. (1999) Health benefits of docosahexaenoic acid (DHA). Pharmacol.
Res. 40: 211-25.
Ikemoto, A., Kobayashi, T., Watanabe, S., and Okuyama, H. (1997) Membrane fatty acid
modifications of PC12 cells by arachidonate or docosahexaenoate affect neurite outgrowth but
not norepinephrine release. Neurochem. Res. 22:671-678.
Ikemoto, A., Nitta, A., Furukawa., Ohishi, M., Nakamura, A., Fujii, Y., and Okuyama, H. (2000)
Dietary n-3 fatty acid deficiency decreases nerve growth factor content in rat hippocampus.
Neurosci. Lett. 285:99-102.
Ikemoto, A., Nitta, A., Furukawa., Ohishi, M., Nakamura, A., Fujii, Y., and Okuyama, H. (2000)
Dietary n-3 fatty acid deficiency decreases nerve growth factor content in rat hippocampus.
Neurosci. Lett. 285:99-102.
Innis SM, Adamkin DH, Hall RT, Kalhan SC, Lair C, Lim M, Stevens DC, Twist PF, DiersenSchade DA, Harris CL, Merkel KL, Hansen JW (2002) Docosahexaenoic acid and arachidonic
acid enhance growth with no adverse effects in preterm infants fed formula. J Pediatr. 140, 54754.
Kitajka, K., Puskas, L.G., Zvara, A., Hackler, L., Barcelo-Coblijn, G., Yeo, Y.K. and Farkas, T.
(2002) The role of n-3 polyunsaturated fatty acids in brain: modulation of rat brain gene
expression by dietary n-3 fatty acids. PNAS 99, 2619-2624.
Kurlack, L.O., and Stephenson, T.J. (1999) Plausible explanations for effects of long chain
polyunsaturated fatty acids on neonates. Arch. Dis. Child Fetal Neonatal Ed. 80:148-154.
Lagarde, M., Bernoud. N., Brossard, N., Lemaitre-Delaunay. D., Thies, F., Croset, M., Lecerf, J.
(2001) Lysophosphatidylcholine as a preferred carrier form of docosahexaenoic acid to the brain.
J Mol Neurosci. 16: 201-4; discussion 215-21.
Lauritzen, L., Hansen, H.S., Jorgensen, M.H. and Michaelson, K.F. (2001) The essentiality of
long chain n-3 fatty acids in relation to development and function of the brain and retina. Prog.
Lipid Res. 40:1-94.
Leaf A, Xiao YF, Kang JX (2002) Interactions of n-3 fatty acids with ion channels in excitable
tissues. Prostaglandins Leukot Essent Fatty Acids. 67, 113-20.
Li, D., Sinclair, A. J., Wilson, A., Nakkote, S., Kelly, F., Abedin, L., Mann, N., and Turner, A.
(1999) Effect of dietary alpha-linolenic acid on thrombotic risk factors in vegetarian men. Am. J.
Clin. Nutr. 69:872-882.
Page 26
DHA and brain
Lin DS, Connor WE, Anderson GJ, Neuringer M. (1990) Effects of dietary n-3 fatty acids on the
phospholipid molecular species of monkey brain. J Neurochem. 55. 1200-7.
Litman, B.J., Niu, S.L., Polozova, A., and Mitchell, D.C. (2001) The role of docosahexaenoic
acid containing phospholipids in modulating G protein-coupled signalling pathways: visual
transduction. J. Mol. Neurosci. 16:237-242.
Mantzioris, E., James, M.J., Gibson, R.A., and Cleland, L.G. (1994) Dietary substitution with an
α-linolenic acid-rich vegetable oil increases eicosapentaenoic acid concentrations in tissues. Am.
J. Clin. Nutr. 59:1304-1309.
Martin, R.E. (1998) Docosahexaenoic acid decreases phospholipase A2 activity in the
neurites/nerve growth cones of PC12 cells. J. Neurosci. Res. 54:805-813.
Martinez, M. (1992) Tissue levels of polyunsaturated fatty acids during early human
development. J. Pediatr. 120: S129-38.
Martinez, M., Vazquez, E., Garcia-Silva, M.T., Manzanares, J., Bertran, J.M., Castello., F., and
Mougan, I. (2000) Therapeutic effects of docosahexaenoic acid ethyl ester in patients with
generalised peroxisomal disorders. Am. J. Clin. Nutr. 71:376S-385S.
Martinez, M. (2001) Restoring the DHA levels in the brains of Zellweger patients. J. Mol.
Neurosci. 16:317-21.
Meyer, B.J., Mann, N.J., Lewis, J.L., Milligan, G.C., Sinclair, A.J., Howe, P.R. (2003) Dietary
intakes and food sources of omega-6 and omega-3 polyunsaturated fatty acids. Lipids. 38: 391-8.
Mitoulas, L.R., Gurrin, L.C., Doherty, D.A., Sherriff, J.L., Hartmann, P.E. (2003) Infant intake of
fatty acids from human milk over the first year of lactation. Br. J. Nutr. 90:979-86.
Moore, S.A., Hurt, E., Yoder, E., Sprecher, H., and Spector, A.A.. (1995) Docosahexaenoic acid
synthesis in human skin fibroblasts involves peroxisomal retroconversion of tetracosahexaenoic
acid. J. Lipid Res. 36:2433-244.
Moriguchi, T., Salem, N. Jr. (2003) Recovery of brain docosahexaenoate leads to recovery of
spatial task performance. J. Neurochem. 87: 297-309.
Neuringer, M. (1993) Lipids, learning, and the brain: fats in infant formulas. Chapter 6, pp135.
Ross Laboratories, Columbus, Ohio.
Nunez M, Peinado-Onsurbe J, Vilaro S, Llobera M. (1995) Lipoprotein lipase activity in
developing rat brain areas. Biol Neonate. 68: 119-27.
O'Dea, K., Steel, M., Naughton, J.M., Sinclair, A.J., Hopkins, G., Angus J., He, G-W., Niall, M.,
and Martin, T.J. (1988) Butter-enriched diets reduce arterial prostacyclin-production in rats.
Lipids 23:234-241.
Page 27
DHA and brain
Owada, Y., Yoshimoto, T., Kondo, H. (1996) Spatio-temporally differential expression of genes
for three members of fatty acid binding proteins in developing and mature rat brains. J Chem
Neuroanat. 12: 113-22.
Pawlosky, R., Hibbeln, J., Lin, Y., Salem, N. Jr. (2003) n-3 fatty acid metabolism in women. Br.
J. Nutr. 90: 994-5.
Pawlosky, R.J., Bacher, J., Salem, N. Jr. (2001) Ethanol consumption alters electroretinograms
and depletes neural tissues of docosahexaenoic acid in rhesus monkeys: nutritional consequences
of a low n-3 fatty acid diet. Alcohol Clin. Exp. Res. 25:1758-65.
Pawlosky, R.J., Salem, N. Jr. (1995) Ethanol exposure causes a decrease in docosahexaenoic acid
and an increase in docosapentaenoic acid in feline brains and retinas. Am. J. Clin. Nutr. 61: 12849.
Peet, M., and Horrobin, F. (1999) Phospholipid spectrum disorders in psychiatry. Chapter One,
pp3.
Pullarkat, R.K., Reha, H. (1978) Acyl and alk-1'-enyl group composition of ethanolamine
phosphoglycerides of human brain. J. Neurochem. 31: 707-11.
Puskas LG, Kitajka K et al 2003 Short-term Administration of Omega-3 Fatty Acids from Fish
Oil results in increased Transthyretin Transcription in Old Rat Hippocampus PNAS 100,1580-85.
Rapoport SI. (2003) In vivo approaches to quantifying and imaging brain arachidonic and
docosahexaenoic acid metabolism. J Pediatr. 143, S26-34.
Reich, E.E, Zackert, W.E., Brame, C.J., Chen, Y., Roberts, L.J. 2nd, Hachey, D.L., Montine, T.J.,
and Morrow, J.D. (2000) Formation of novel D-ring and E-ring isoprostane-like compounds
(D4/E4-neuroprostanes) in vivo from docosahexaenoic acid. Biochemistry 39:2376-83.
Reich EE, Markesbery WR, Roberts LJ 2nd, Swift LL, Morrow JD, Montine TJ. (2001)
Quantification of F-ring and D-/E-ring isoprostanes and neuroprostanes in
Alzheimer's disease. Adv Exp Med Biol. 500, 253-6.
Robert J, Montaudon D, Hugues P. (1983) Incorporation and metabolism of exogenous fatty
acids by cultured normal and tumoral glial cells. Biochim Biophys Acta. 752: 383-95.
Roberts, L.J. 2nd, Montine, T.J., Markesbery, W.R., Tapper, A.R., Hardy, P., Chemtob, S.,
Dettbarn, W.D., and Morrow, J.D. (1998) Formation of isoprostane-like compounds
(neuroprostanes) in vivo from docosahexaenoic acid. J. Biol. Chem. 273:13605-12.
Rojas, C.V., Greiner, R.S., Martinez, J.I., Salem Jr., N. and Uauy, R. (2002) Long-term n-3 fatty
acid deficiency modifies peroxisome proliferator-activated receptor beta mRNA abundance in rat
ocular tissues. Lipids 37:367-374.
Rousselot, P., Heintz, N., Nottebohm, F. (1997) Expression of brain lipid binding protein in the
brain of the adult canary and its implications for adult neurogenesis. J Comp Neurol. 385: 41526.
Page 28
DHA and brain
Ryan AS, Montalto MB, Groh-Wargo S, Mimouni F, Sentipal-Walerius J, Doyle J,
Siegman JS, Thomas AJ. (1999) Effect of DHA-containing formula on growth of preterm infants
to 59 weeks postmenstrual age. Am J Human Biol. 11, 457-467
Salem N, Lin Y, Brenna JT, Pawlosky RJ (2003) Alpha-linolenic acid conversion revisited.
PUFA Newsletter (Roche), www.fatsoflife.com December 2003
Salem Jr., N., and Ward, G.R. (1993) Are omega-3 fatty acids essential nutrients for mammals?,
World Rev. Nutr. Dietet. 72:128-147.
Salem Jr., N., Litman, B., Kim, H-Y. and Gawrisch, K. (2001) Mechanisms of acytion of
docosahexaenoic acid in the nervous system. Lipids 36:945-959.
Salem Jr., N., Wegher, B., Mena, P., and Uauy, R. (1996) Arachidonic and docosahexaenoic
acids are biosynthesised from their 18-carbon precursors in human infants, Proc. Natl. Acad. Sci.
93:49-54.
Sastry, R.S. (1985) Lipids of nervous tissue: Composition and metabolism. Prog. Lipid Res.
24:69.
Seebungkert, B., Lynch, J.W. (2002) Effects of polyunsaturated fatty acids on voltage-gated K+
and Na+ channels in rat olfactory receptor neurons. Eur. J. Neurosci. 16: 2085-94.
Sinclair AJ. (1975a) Long-chain polyunsaturated fatty acids in the mammalian brain. Proc Nutr
Soc. 34, 287-91.
Sinclair, A.J. (1975b) Incorporation of radioactive polyunsaturated fatty acids into liver and brain
of developing rat. Lipids. 1975 Mar; 10: 175-84.
Sinclair, A.J., Attar-Bashi, N.M., and Li, D. (2002) What is the role of alpha-linolenic acid for
mammals? Lipids 37:1113-23.
Spector, A.A, Yorek, M.A. (1985) Membrane lipid composition and cellular function. J. Lipid
Res. 25:1015-1035.
Svennerholm, L. (1968) Distribution and fatty acid composition of phosphoglycerides in normal
human brain. J. Lipid Res. 9: 570-9.
Thompson, G.A., ed. The regulation of membrane lipid metabolism. 2nd edn. Boca Raton: CRC
Press, 1992.
Uauy, R., Hoffman, D.R., Birch, E.E., Birch, D.G., Jameson, D.M., Tyson, J. (1994) Safety and
efficacy of omega-3 fatty acids in the nutrition of very low birth weight infants: soy oil and
marine oil supplementation of formula. J. Pediatr.124: 612-20.
Uauy R, Hoffman DR, Mena P, Llanos A, Birch EE (2003) Term infant studies of DHA and
ARA supplementation on neurodevelopment: results of randomized controlled trials. J Pediatr.
143, S17-25.
Page 29
DHA and brain
Umezawa, M., Kogishi, K., Tojo, H., Yoshimura, S., Seriu, N., Ohta, A., Takeda, T., and
Hosokawa, M. (1999) High-linoleate and high alpha-linolenate diets affect learning ability and
natural behaviour in SAMR1 mice. J. Nutr. 129:431-437.
Utsunomiya, A., Owada, Y., Yoshimoto, T., Kondo, H. (1997) Localization of mRNA for fatty
acid transport protein in developing and mature brain of rats. Brain Res. Mol. Brain Res. 46: 21722.
Vaidyanathan, V.V., Rao, K.V.R. and Sastry, P.S. (1994) Regulation of diacylglycerol kinase in
rat brain membranes by docosahexaenoic acid. Neurosci Lett 179:171-174.
Vanderhoof, J., Gross, S., Hegyi, T., Clandinin, T., Porcelli, P., DeCristofaro, J., Rhodes, T,
Tsang, R., Shattuck, K., Cowett, R., Adamkin, D., McCarton, C., Heird, W., Hook-Morris, B.,
Pereira, G., Chan, G., Van Aerde, J., Boyle, F., Pramuk, K., Euler, A., Lien, E.L. (1999)
Evaluation of a long-chain polyunsaturated fatty acid supplemented formula on growth,
tolerance, and plasma lipids in preterm infants up to 48 weeks postconceptional age. J. Pediatr.
Gastroenterol. Nutr. 29: 318-26.
Vanderhoof, J., Gross, S., Hegyi, T. (2000) A multicenter long-term safety and efficacy trial of
preterm formula supplemented with long-chain polyunsaturated fatty acids. J. Pediatr.
Gastroenterol. Nutr. 31: 121-7.
Vilaro, S., Camps, L., Reina, M., Perez-Clausell, J., Llobera, M., Olivecrona, T. (1990)
Localization of lipoprotein lipase to discrete areas of the guinea pig brain. Brain Res. 506: 24953.
Voss, A.M., Reinhart, S., Sankarappa, S. and Sprecher, H. (1991) Metabolism of 22:5n-3 to
22:6n-3 in rat liver is independent of 4-desaturase. J. Biol. Chem. 266,19995-20000.
Watanabe S, Doshi M, Hamazaki T. (2003) n-3 Polyunsaturated fatty acid (PUFA) deficiency
elevates and n-3 PUFA enrichment reduces brain 2-arachidonoylglycerol level in mice.
Prostaglandins Leukot Essent Fatty Acids. 69, 51-9.
Wheeler, T.G., Benolken, R.M., and Anderson, R.E. (1975) Visual membranes: specificity of
fatty acid precursors for the electrical response to illumination, Science, 188, 1312-1314
Yep YL, Li D, Mann NJ, Bode O, Sinclair AJ. (2002) Bread enriched with microencapsulated
tuna oil increases plasma docosahexaenoic acid and total omega-3 fatty acids in humans. Asia
Pac J Clin Nutr. 11, 285-91.
Zimmer, L., Dellion-Vaancassel, S., Durand, G., Guilloteau D., Bodard, S., Besnard, J.C., and
Chalon, S. (2000) Modification of dopamine neurotransmission in the nucleus accumbens of rats
deficient in n-3 polyunsaturated fatty acids. J Lipid Res. 41:32-40.
Page 30
DHA and brain
Appendix 1: Concentration of DHA in the brains of animals
Animal
Concentration in brain
Rat
• Whole brain of adult rats is10-15% DHA (Bernardini et al 1978,
Fehling et al 1978, Walket et al 1972)
• Ethanolamine phosphoglycerides of synaptosomal membranes
(Breckenridge et al 1971, Breckenridge et al 1972, Breckenridge et
al 1973) and synaptosomes (Cotman et al 1969) contained 30-36%
DHA.
• Total fatty acids of rat brain mitochondria (Yatsu and Moss 1971) or
mitochondrial ethanolamine phosphoglycerides is 15-30% DHA.
Mouse
•
•
Rabbit
•
Guinea pig
•
Pig
•
Cattle
•
•
Sheep
•
Deer
•
Mink
•
Whales and
Dolphins
•
•
Page 31
Whole mouse brains contain between 15-16% DHA of total fatty
acids (McMullin et al 1968, Meier and MacPike 1970).
Ethanolamine phosphoglycerides from whole mouse brain
homogenate contained 25% DHA while Ethanolamine
phosphoglycerides in mylin from these brains was 7% DHA (Sun
and Samorajski 1972).
DHA increased with age from 11-17% of nerve cell bodies of rabbit
cerebral cortex in ethanolamine phosphoglycerides and from 1621% in fatty acids of serine phosphoglycerides (Baker 1979).
DHA accounted for 14% of total fatty acids in ethanolamine
phosphoglycerides from synaptic plasma membranes (Sun and Sun
1979)
Whole brain of pigs and newborn piglets contained about 11% of
total fatty acids as DHA (Sweasy et al 1976)
Cerebral cortex PL contains 11% of total fatty acids as DHA
(Gonazto and Toffnao 1973).
In fetal bovine brain, DHA was 20% of total fatty acids in PL
(Payne 1978).
DHA accounted for 29% of total fatty acids in whole fetal lamb
brain and 19% of total fatty acids in PL of adult sheep brain (Payne
1978).
DHA accounted for 14 % of total fatty acids of newborn deer claves
brain PL and 13% of total fatty acids in adult deer brain (Payne
1978).
DHA accounted for 16 % of total fatty acids of whole mink brain
(Walker and Lishchenko 1966).
DHA in brains of pilot whales was highest in ethanolamine
phosphoglycerides where it was 19% in cerebral cortex and 8% in
the cerebellum (Lesch et al 1968).
In Dolphins, DHA was highest in the fatty acids of ethanolamine
phosphoglycerides where it was 17% in cerebral cortex, 10% in
cerebellum and 2-6% in cerebral medulla, midbrain and pons
(Bernhard 1969)
DHA and brain
Appendix 2: shows DHA levels in regions of the brain in humans.
Reference
Age of subjects
1
2
3
No. of
subjects
58
34
28
4
16
<1 y
5
35
2-28 wk
6
7
8
20
40
16
<43 wk
26-87 y
61-87 y
9
10
11
9
13
11
18-77 y
newborn-81 y
newborn-55 y
Frontal cortex and
white matter
Cerebral cortex
Whole brain
Frontal lobes
(microsomes and
synaptosomes)
Frontal lobes
Grey matter
Grey matter
12
4
10 mh-55 y
Grey matter
13
2
55-80 y
Grey matter
14
13
61-89 y
Cerebral cortex
15
16
14
6
43-77 y
62-85 y
Caudate region
Cerebral cortex
17
3
24-52 y
Cerebral cortex
18
10
47-87 y
19
7
64-88 y
Grey matter
(parietal, frontal,
parahippocampal)
Frontal cortex
20
5
59-91 y
Cerebral cortex
21
15
48-86 y
Frontal cortex
22
4
16-76 y
Cerebral cortex
23
24
5
6
14-56 y
50-80 y
Frontal cortex
Grey matter
Page 32
1-88y
<6 mth
3-48 wk
Region of brain
analysed
Frontal cerebral cortex
Cerebellar cortex
Frontal lobe and brain
stem
Cerebral cortex
DHA levels
7-16g/100g brain sample??
4.98-6.16 % of total FA
FL: 7.6-8.5 % of total FA
BS: 4.4-4.8 % of total FA
PE: 11.6-17.7 % of total FA
PS: 14.4-23.5 % of total FA
7.5-8.5 % of total FA
4-11 % of total FA
0.9-2.5 % of total FA
PE: 29.6-31.1% of total FA
PS+PI: 22.7-23.1% of total FA
PE: 7.3-10.3 mol %
CE?: 4.0-6.4 % of total FA
PE: 10.8-33.9 % of total FA
PC: 0.7-3.6 % of total FA
PS: 13.7-29.8 % of total FA
PE: 16.7-24.3 % of total FA
PC: 1.0-3.1 % of total FA
PS: 23.5-36.6 % of total FA
PE: 24.0-25.2 % of total FA
PC: 3.1 % of total FA
PS: 15.7-36.6 % of total FA
PE, PC, PS???
15.9 mol. %
PL: 9.6 nmol/mg dry weight
PE: 20.7 % of total FA
PC: 1.6 % of total FA
PS: 25.0 % of total FA
Total lipids: 9.2% of total FA
Total PL: 9.6 % of total FA
16.9-18.6 % of total FA
PE: 34.0 % of total FA
PC: 4.3 % of total FA
PS: 9.4 % of total FA
PE: 19.6 % of total FA
PC: 1.7 % of total FA
PS: 8.8 % of total FA
PE: 24.5-25.9 % of total FA
PC: 2.3-2.5 % of total FA
PS: 21.0-21.2 % of total FA
PE: 32.4 % of total FA
PC+PS: 2.5 % of total FA
PC: 2.2-2.9% of total FA
PE: 5.7 % of total FA