A new study shows that consuming the right ratio of essential fatty acids is key during pregnancy.
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 and omega-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.
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.
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.
Medical News Today recently covered a study showing that omega-3 can help ward off rheumatoid arthritis.