The effect of diet on the unborn child is not only a vital
area of study, but it is also an incredibly complex one. A recent study delves
into the mechanisms behind omega fatty acids and the development of the fetal
brain.
The importance of diet during pregnancy is clear and needs no
in-depth explanation.
As
the baby develops, it needs access to all the components necessary to build an
entire functioning human.
Because
the development of the brain is largely completed during its stay in the womb,
the impact of any dietary deficits is likely to be more significant than for
other organs.
A recent study carried out at Tohoku University's School of
Medicine in Japan looked at the role of dietary fatty acids - omega-6 andomega-3 - in the developing fetuses of rats.
The
importance of omega acids is well documented, but this latest study, led by
Prof. Noriko Osumi, delved into the specific mechanisms involving fatty acids
during the development of the embryo's brain.
The importance of omega-3 fatty acids
Both
omega-3 and omega-6 are referred to as essential fatty acids because they
cannot be generated by the body itself; they must, therefore, be taken in
through the diet.
The roles of omega oils in the
body include the storage of energy, oxygen transport, functioning of cell
membranes and inflammation regulation.
Omega-3
oils are predominantly found in marine fish. The most common forms are
docosahexaenoic acid and eicosapentaenoic acid. In the US, because of the
relatively low level of fish in the diet, these oils are often not consumed in
adequate quantities.
Previous research has demonstrated the importance of omega-3
during pregnancy. It plays a role in determining the length of gestation and in
staving off depression before and after birth.
Omega-3
oils have also been shown to increase the rate of brain growth in the fetus and
throughout the first year of life. These oils are particularly important in the
development of the eye. Animal fetuses deprived of omega-3 show marked visual
and behavioral changes that cannot be rectified by healthy diets after birth.
Omega-6/omega-3 ratios
Prof.
Osumi and his team wanted to look at the effect of a change in ratios of omega
oils. By feeding pregnant rats a diet rich in omega-6 and poor in omega-3, they
mimicked the ratios found commonly in diets around the world today.
Omega-6 is more commonly found
in seed oils, and omega-3 is almost exclusively found in fish.
Once
the rat mothers had given birth, the team found that the brains of the
offspring with the omega-6-rich/omega-3-poor diets were significantly smaller
than those whose mothers had consumed a more balanced diet with equal amounts
of 3 and 6.
Interestingly,
and perhaps worryingly if we are to extrapolate the findings, the rat offspring
subjected to the skewed dietary ratios in the womb also exhibited changes in
emotional behavior.
The offspring of the low omega-3 mothers showed increased anxiety in
adulthood, despite having been supplied with a healthy diet from birth.
Omega-based changes
Similar
deficits have been demonstrated in previous studies, but Prof. Osumi and his
colleagues delved into the mechanisms behind the findings to see what specific
changes occurred during the development of the fetal brain under such
conditions.
The team performed the first comprehensive measurement of lipid
metabolites in the developing brain; they identified that metabolites of omega
oils are vital regulators of neural stem cells - the cells that go on to develop into
fully fledged brain cells.
In the rats with diets heavier on the omega-6 than 3, the neural
stem cells developed more rapidly, to their detriment. The results, published
in the journal Stem
Cells, show that increased levels of omega-6 produce an increase in
omega-6 oxides. These omega offshoots cause premature aging of fetal neural
stem cells.
The
study's authors conclude:
"These findings provide compelling evidence that
excess maternal consumption of omega-6 combined with insufficient intake of
omega-3 causes abnormal brain development that can have long-lasting effects on
the offspring's mental state."
The general recommendation is that omega-6 and omega-3 should be
consumed at a 1:1 ratio, but it is not uncommon for some American diets to be
as skewed as 16:1. A general fear of mercury poisoning is often cited as a
reason to reduce the amount of marine fish eaten.
Because
of this genuine concern, the recommendation for pregnant women from the US Food
and Drug Administration is 8-12 oz of fish weekly.
This
maximizes the positive influence of omega-3 and minimizes the risk of
mercury-based concerns.
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