I was reading mayo clinic's "breast milk: revisited". It is 1998 publication but quite interesting, especially the section re chemical pollutants found in human milk. I copying some parts of the paper. As this is a bit old document, I wanted to ask whether anybody has any up to date information about this issue.
"Breast milk: Revisited
Aida N Lteif, W Frederick Schwenk II. Mayo Clinic Proceedings. Rochester: Aug 1998. Vol. 73, Iss. 8; pg. 760, 4 pgs
Abstract (Summary)
Human milk has been shown to be the ideal source of nutrition for most growing infants. Its composition continues to be an active area of investigation. In several studies in preterm and term infants, long-chain polyunsaturated fatty acids were found to improve the maturation of visual evoked potentials. The clinical significance of this finding, however, remains unclear. Nucleotides present in breast milk or added to infant formula seem to enhance the humoral immune response to vaccination. Whether breastfeeding protects susceptible infants from the risk of the development of diabetes mellitus type 1 is still controversial. Breastfeeding by mothers infected with the human immunodeficiency virus is not recommended. Other viruses and pollutants have also been found in breast milk. The importance of these in the long-term health of children remains to be established.
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LC-PUFAs AND BREAST MILK
One of the major differences between breast milk and commercial formulas has been that breast milk contains many LC-PUFAs. LC-PUFAs are important components of all cellular membranes, especially in the developing retina and the gray matter of the brain. They seem to be essential for neurodevelopment because their incorporation in central nervous system tissues continues during the first 2 years of life."
Studies comparing formula-fed and breast-fed infants have shown that infants who are fed commercial formula have less docosahexaenoic acid (22:6n-3) in their brain cortex than do breast-fed infants.'2 Some prospective studies have shown that improved neurologic function, specifically better visual evoked potentials, can be associated with breastfeeding rather than with formula feeding. Some investigators have suggested that the maturation pattern of visual evoked potentials is slower in preterm infants who did not receive LC-PUFAs." These findings, however, have not been substantiated by all investigators." In addition, the clinical significance of the improved visually evoked potentials is unclear.
Despite the unclear nature of these findings, LC-PUFAs have been added to some commercial formulas. When LCPUFAs are included, the antioxidant requirements are higher. Vitamin E may need to be increased in these formulas." LC-PUFAs contain a large number of unsaturated double bonds. Therefore, there is an increased potential for oxidation that results in the increased requirement for antioxidant protection. The American Academy of Pediatrics has no current recommendation regarding the addition of LC-PUFAs."
BREAST MILK AND NUCLEOTIDES
Nucleotides (naturally present in breast milk) seem to be essential nutrients for rapidly dividing tissues such as the intestinal epithelium and lymphoid cells. In rats, data support the importance of nucleotides for normal development, maturation, and repair of the gastrointestinal tract.'3 In normally growing infants, however, nucleotide supplementation does not seem to have a significantly beneficial effect on the gastrointestinal tract.'4 Clinical studies that have shown a benefit are limited to one that reported improved growth in a group of infants who were small for gestational age"4 and one that reported a lower incidence of diarrhea-related disease.'5
In addition to their effect on the gastrointestinal tract, nucleotides have also been implicated to be important for the immune system. Studies in mice have shown that restriction of dietary nucleotides decreases cell-mediated immunity. Human studies suggest that the humoral immune response of preterm and term newborns is increased when nucleotides are added to their formulas.'617
Breast milk is the best source of nucleotides for infants. In the absence of breastfeeding, the addition of nucleotides to infant formula within the range of concentrations found in mature human milk seems to be safe. Strong evidence for the clinical efficacy of nucleotide supplementation is still lacking, but numerous studies are currently under way.
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IS BREAST MILK POLLUTED?
Although substantial attention has been given to the risks of breastfeeding when the mother is taking prescription drugs, less consideration has been given to the presence of chemical pollutants in human milk. During the past 4 decades, some members of the DDT (2,2[4-chlorophenyl]1,1,1-trichloroethane) family have been detected in all samples of human milk worldwide. Additional compounds often found in human milk have included hexachlorobenzene, cyclodiene pesticides, and polychlorinated biphenyls.zo These compounds are not well excreted through urine and stool, and they occur in higher concentrations in human milk than in the serum of the mother. Such compounds do not seem to be in such high concentrations in cow's milk, either because of less exposure or because the increased milk production in cows dilutes the concentrations.
Currently, data confirming morbidity in infants exposed to these chemicals through breastfeeding have been minimal, although mass poisonings have been reported in infants affected through breast milk. Laboratory research, however, has confirmed that the developing neurologic system is particularly sensitive to some of these chemicals. Whether exposure to such chemicals predisposes the infant or mother (or both) to an increased risk of the development of cancer remains to be established.20 The presence of these compounds in breast milk is an additional reason for decontamination of the environment. Despite the presence of these chemical residues, breastfeeding continues to be recommended because its benefits seem to outweigh its risks.
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