What is the effect of the mother's diet on the quality of the breast milk?
Also, to the best of my knowledge, England is not known for healthy dietary
practices.  Might the outcome of this study be different in another country?

Siobhan


<<We found that distensibility of the brachial artery in young adults was
related to the duration of breast feeding in infancy. Longer duration of
breast feeding was associated with stiffer arteries. As we studied young
adults, our results are less likely to be confounded by the effects of other
cardiovascular risk factors that are present in older cohorts. The results
suggest that the effect of breast feeding on cardiovascular risk occurs
early in life.

Possible explanations for the effect
Breast feeding evolved in mammals over millions of years and is generally
considered optimal for humans. The commonly cited advantages over formula
feeding include reduced infection and atopy and increased cognitive
development.12 The optimal duration of breast feeding remains inadequately
researched. We found an apparent adverse outcome in people who had had
prolonged breast feeding. This finding is consistent with the results of an
observational study in which men who had been breast fed at 1 year had an
increased risk of ischaemic heart disease 60 years later.2 This finding was
suggested to be due to programming of cholesterol metabolism in response to
the unique lipid or hormone contents of breast milk. These factors might
alter expression of hepatic enzymes or low density lipoprotein receptors,
changing the response to a high fat diet later in life.13-16 This hypothesis
is consistent with the experimental studies in primates, where breastfed
baboons given a Western style high saturated fat diet had more early
atherosclerotic changes in adulthood than formula fed animals.

In our study, however, longer duration of breast feeding was not associated
with significantly higher total cholesterol or lipoprotein concentration in
adulthood. Furthermore, models relating breast feeding to distensibility
were not affected by inclusion of current lipid profile. Thus our results do
not support a hypothesis of deranged blood lipid profiles in adulthood.

An alternative hypothesis would be that breast feeding influences lipid
metabolism much earlier, during the infant feeding period, resulting in
early formation of arterial fatty streaks. Animal studies show arterial
elasticity is reduced during fatty streak formation in infancy before other
pathophysiological changes.17 Cholesterol is laid down in the vessel wall
from the first months, with a peak prevalence of fatty streaks during the
first year18 when cholesterol concentrations are higher in breastfed
infants. 19 20 If breast feeding is extended throughout infancy, the vessel
wall is exposed to raised circulating cholesterol concentrations for longer.
Most arterial lesions seem to regress initially, but in the primate studies
above, animals breast fed as infants and then placed on a high saturated fat
diet had more fatty streaks in adulthood.1 In humans, such early arterial
changes might persist into later life if subsequent diet interferes with
their natural regression. A small, inconclusive postmortem study of
adolescents showed more arterial lesions in those who had been breast fed,
further supporting an early effect of breast feeding.21 More work is needed
to investigate dietary differences in vascular lipid deposition in early
life.

Relevance of arterial distensibility
Arterial distensibility is known to diminish with age in relation to
cardiovascular risk factors and is reduced in subjects with frank coronary
disease. 22 23 Indeed, the potential impact of such risk factors is apparent
in this study, which showed reduced arterial distensibility in young adults
with higher blood pressure, cholesterol, or body mass index. Although
further investigation is needed, it seems likely that arterial
distensibility is related to risk of vascular disease.

There was no direct record of feeding method or duration. We used maternal
recall, which has been independently validated for collecting such data9 and
provides reproducible data 30 or more years after birth.24 Further early
dietary information was limited as the study was retrospective. Prospective
investigations could take account of age of weaning and subsequent diet as
well as the more recent secular changes in infant feeding, notably duration
of use and design of infant formula.>>