Fish Oil and Pregnancy, Infants' Health

TORONTO, CANADA. A team of researchers from Canada, Britain, and the USA emphasize the importance of ensuring that newborn infants get sufficient docosahexaenoic acid (DHA) in order to ensure optimal neural and visual development during the first 6 months of life. They point out that there is still controversy as to whether the required DHA can be synthesized by the infants themselves (from alpha-linolenic acid) or must be supplied by the diet - be it breast milk or infant formula.

The researchers reviewed numerous studies comparing the docosahexaenoic acid status of breast-fed infants with that of formula-fed ones. They found that over the first 6 months of life docosahexaenoic acid accumulates in the body of breast-fed infants at a rate of 10 mg/day with 48% of this accumulation occurring in the brain. They estimate that an intake of 20 mg/day of DHA is required to achieve this accumulation and point out that breast feeding supplies about 60 mg/day. They believe the seeming over-abundance of docosahexaenoic acid in breast milk may be needed in order to provide for potentially increased losses during disease, infection, surgery, and other conditions adversely affecting the infants' metabolism.

On the other hand, formula-fed infants would seem to develop a serious deficiency of docosahexaenoic acid if they are fed a formula which has not been fortified with DHA (usually in combination with arachidonic acid). Standard infant formulas contribute about 390 mg/day of alpha-linolenic acid so about 5.2% of this would have to be converted to docosahexaenoic acid in order to produce the needed 20 mg/day. The researchers point out that there is no evidence at all that infants are able to achieve this conversion rate and speculate that the rate may be as much as 20 times lower than required. This conclusion is amply supported by the fact that formula-fed infants actually lose 993 mg of DHA over the first 6 months of life while breast-fed babies gain an average of 1882 mg. The accumulation of docosahexaenoic acid in the brain of formula-fed infants is only half of that observed in breast-fed infants and while the liver in breast-fed infants gains 24 mg of DHA during the first 6 months the liver in formula-fed ones actually loses 136 mg.

The researchers conclude that feeding infants with a non-fortified formula will not provide the docosahexaenoic acid provided by breast milk. They urge further work to determine whether a formula containing at least 0.2% DHA (providing 60 mg/day of DHA) will provide equivalent DHA accumulation to that of breast-fed infants.
Cunnane, Stephen C., et al. Breast-fed infants achieve a higher rate of brain and whole body docosahexaenoate accumulation than formula-fed infants not consuming dietary docosahexaenoate. Lipids, Vol. 35, January 2000, pp. 105-11

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