Title: Supplementation of infant formulas with long chain polyunsaturated fatty acids
Key words: long chain, polyunsaturated, polyunsaturates, fatty acids, LCPUFA, deficiencies, development, developmental, cognitive, mental, physical, formula milk, infant formula, n-3, n-6, cow’s milk, elongase, desaturase, arachidonic acid, docosahexaenoic acid, breast milk, mother’s milk, cortex, retina, DHA, retinitis pigmentosa, fish oils, maternal nutrition, essential fatty acids, neural maturation, sequelae,
Date: Oct 2006
Author: Morgan, G
Supplementation of infant formulas with long chain polyunsaturated fatty acids
There is now considerable evidence to show that long chain polyunsaturated fatty acids (LCPUFAs) are essential for normal maturation of the developing infant and deficiencies can lead to lead to long-term consequences in terms of mental, cognitive and physical development. Formula milk is lacking in both LCPUFAs of the n-3 and n-6 series and has been held responsible for many of these developmental problems. The evidence is reviewed here.
In an early longitudinal study looking in children born in 1946, Rogers (1978) found that children raised on cow’s milk had a lower IQ at age 8 and impaired mathematical, verbal and non-verbal ability at age 15 compared with breast fed children. Other workers, such as Rogan (1993), confirmed these findings with later formula milks. Mental and cognitive scores were found to be consistently lower in such children and was most marked in those born prematurely or those that remained on formula milk for a long period. Thus, formula fed preterm infants, at the age of 8, were found to have an IQ some 8 points lower than breast fed infants (Lucas 1992) and infants brought up on human milk for at least 21 days, at the age of 9, had half the number of cognitive defects (Lanting 1994).
Arachidonic acid and docosahexaenoic acid (DHA) have both been held to be essential for normal brain maturation. It is thought that elongase/ desaturase deficiencies in early life makes the young brain dependant on the mother for these essential LCPUFAs, either via the placenta or through mother’s milk. This is especially the case with the n-3 PUFA DHA which shows a steady decline in infancy in formula fed babies. There is a high content of essential fatty acids in the brain and levels of DHA reach up to 50% in some areas of the cortex and retina (Uauy 1996) paralleling its functional importance. Cognitive and retinal electrophysiological function has been shown to be most dependent on this fatty acid, plasma DHA, for example, correlating closely with psychomotor movements at 1 year (Bjerve 1992) and congenital deficiency of retinal DHA being associated with retinitis pigmentosa (Uauy). n-6 LCPUFA has also been found to be essential, fish oils in amounts large enough to suppress arachidonic acid synthesis being associated with physical developmental problems in infancy (Carlson 1992).
Maternal nutrition is important in providing the infant with an adequate supply of essential fatty acids. Studies show that in the third trimester, the time of maximum foetal brain development, maternal DHA reserves are depleted to help support foetal brain growth. Low maternal reserves may prove critical as Makrides (1995) has shown that in Australian women, for example, DHA levels in mother’s milk has declined from 0.32% to 0.21% over the last 10 years. It was estimated that 0.30% is necessary to maintain infant brain DHA levels for 30 weeks. One can deduce from this that DHA levels in the pregnant woman are already low and that institution of formula feeding could well lead to developmental problems.
Longitudinal studies such as those of Lanting (1994) have led some workers to believe that, during the third trimester and early months of life, neural maturation is so sensitive that a window exists during which an inadequate supply of LCPUFAs can learn to permanent cognitive and physical sequelae. Physical sequelae affecting blood pressure and the respiratory system have been described (Forsyth 2001).
Work looking at LCPUFA supplementation of formula milks have shown reversal of cognitive and psychomotor deficiency changes (Forsyth 2001). This both serves to corroborate the validity of the model described above and confirms that social and other variables are not operative against this background. The conclusion is that supplementation of all infant formulas is now justified.
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