http://bmj.com/cgi/content/full/323/7314/689/a
BMJ 2001;323:689 ( 22 September )
Letters
Duration of breast feeding and adult arterial distensibility
Humans
are primates, designed to breast feed for years not months
Explanation
of findings and context before publication might have been helpful
Dose-response,
cause and effect relation between breast feeding and heart disease seems
unlikely
Authors
did not discuss data from prospective studies
Does
this study herald the return of national dried milk?
Breast
feeding: distension or distortion?
Statistical
analysis was unclear
Authors'
reply
Summary
of rapid responses
Humans are primates, designed to breast feed for years
not months
With
respect to the article by Leeson et al on duration of breast feeding and
arterial distensibility in early adult life, of course the duration
of breast feeding mattersthe
longer the better.1
Humans are animals, mammals, and primates. Research on correlates of weaning
age in non-human primates, such as adult body size, length of
gestation, timing of permanent tooth eruption, timing of sexual
maturity, and growth rates during childhood, predict that modern
humans should be breast fed for between two and a half and seven
years.23
Humans have slightly longer durations of all stages of the life span
than our nearest relatives, chimpanzees. We have slightly longer
gestation, later dental eruption, later sexual maturity, and
therefore would expect slightly later ages of weaning. Chimpanzees
breast feed for four to five years. Around the world, many children
are breast fed for two and a half to seven years, including some in
the United States, Canada, and Great Britain.
Maybe a healthy start in life of several to many years of breast feeding
should be followed by a lifelong diet low in animal protein and fat
and high in physical exercise, to maximise heart health in
adulthood. But we will not know this until researchers study the
effects on blood vessel flexibility of normal durations of breast
feeding (2.5-7.0 years), and of the combination of normal durations
of breast feeding with different post-weaning diets and amounts of exercise.
I find it appalling that researchers would suggest that more than
four months of breast feeding could be harmful to children, when
research shows that 2.5-7.0 years is clearly the normal and
natural duration for our species. On a final note, it is always good
advice to question the credibility of research and researchers
funded by infant formula companies.
Katherine A Dettwyler
Texas A&M University, College Station, TX 77843-4352, USA kadettwyler@hotmail.com
Competing interests: None declared.
|
1. |
Leeson CPM, Katternhorn M, Deanfield JE, Lucas A. Duration
of breast feeding and arterial distensibility in early adult life: population
based study. BMJ 2001; 322: 643-647 |
|
2. |
Dettwyler KA. A time to wean: the hominid blueprint for
the natural age of weaning in modern human populations. In: Stuart-Macadam P,
Dettwyler KA, eds. Breastfeeding: biocultural perspectives. New York:
Aldine de Gruyter, 1995:39-73. |
Explanation of
findings and context before publication might have been helpful
Perhaps
it is not surprising that the report by Leeson et althat
breast feeding followed by a high fat diet may later be associated
with stiffer arteriesdrew
so many responses.1
Breast feeding is a sensitive topic. The normalising of artificial feeding
by formula companies and the media requires efforts to protect
breast feeding. But we should not allow our protective stance to
become blindly defensive. It is easy to fall into the teleological
trap of believing that breast feeding was designed, by God or
nature, to be perfect. It is possible that evolution could have had
this result. During our evolution we have had much shorter life
spans than we have achieved recently and eaten much less fat. This
is a sound study that adds a piece to the complex puzzle of how
early nutrition may influence adult disease risks. It does not prove
that breast feeding increases the risk of heart disease.
In their attempts to counter the study's conclusions, many of the
respondents tilt at windmills. Some point out that rates of heart
disease are low in developing countries where breast feeding for two
years or more is common. But with changing diets and a higher
proportion of elderly people, rates of heart disease are increasing
rapidly in developing countries.2 Many
have dismissed the findings because they are based on maternal
recall. This is an important epidemiological issue, which can be
studied by comparing mother's recall with clinic records. Such
studies show that mothers can accurately recall breastfeeding
duration for as long as 29 years, but they are less reliable at
recalling age at introduction of formula. 3 4 A
Queensland study found that the differences in breastfeeding
duration as recalled by 75 mothers (over one to 10 years)
and recorded by the clinic were less than one month for 79% of
children, and less than two months for 95% of children.5 They
found no difference in accuracy of recall between mothers with
different levels of education, or with numbers or ages of children.
Leeson et al described the limitations of their study and emphasised that it
should not lead to any change in infant feeding recommendations. It
is unfortunate but predictable that the media will sensationalise
such research reports. If advocates of breast feeding fostered links
with reputable infant nutrition researchers such as Lucas's team,
perhaps an appropriate explanation of the findings and context could
be prepared before publication. Midwives and breast feeding
counsellors could then use this to reassure parents.
Wendy Holmes
International Health Unit, Macfarlane Burnet Centre for Medical Research,
Fairfield, Victoria 3078, Australia holmes@burnet.edu.au
Competing interests: None declared.
|
1. |
Leeson CPM, Katternhorn M, Deanfield JE, Lucas A. Duration
of breast feeding and arterial distensibility in early adult life: population
based study. BMJ 2001; 322: 643-647 |
|
2. |
Murray C, Lopez A. Mortality by cause for eight regions of
the world: global burden of disease study. Lancet 1997; 349: 1269-1276 |
|
3. |
Troy LM, Michels KB, Hunter DJ, Spiegelman D, Manson JE,
Colditz GA, et al. Self-reported birthweight and history of having been
breastfed among younger women: an assessment of validity. Int J Epidemiol
1996; 25: 122-127 |
|
4. |
Kark JD, Troya G, Friedlander Y, Slater PE, Stein Y.
Validity of maternal reporting of breastfeeding history and the association
with blood lipids in 17 year olds in Jerusalem. J Epidemiol Community
Health 1984; 38: 218-225 |
|
5. |
Eaton-Evans J, Dugdale AE. Recall by mothers of the birth
weights and feeding of their children. Hum Nutr Appl Nutr 1986; 40A:
171-175 |
Dose-response,
cause and effect relation between breast feeding and heart disease seems
unlikely
Once
again epidemiological data from the United Kingdom are leading to a claim that
extended breast feeding may lead to later adverse cardiovascular
outcomes. 1
2
Leeson et al say that their findings are consistent with those of
Fall et al, which were widely publicised in the media. 1 3 The
causal mechanism postulated by Fall et al was not found to hold in
this study, and the results do not support a hypothesis of deranged
blood lipid profiles in adulthood. Will this failure to confirm the
previous hypothesis receive attention, or will the media say that
this study "confirms" the findings of the previous one?
We will never know the impact of breast feeding on human health because it
is unethical to randomise. Thus we have to be very careful to look
for confounders when we do associative studies such as this, and
Leeson et al made an effort to do so. Presumably, however, families
with children who breast fed for longer periods in the United
Kingdom 20-30 years ago differed from those who fed their
babies closer to the norm of the time. Slightly over a quarter of
British babies were breast fed for longer than four months in 19804;
similar to the proportion of those contacted who agreed to
participate in this study.
The demographic and health survey data for South Asian countries show that
about half the children are breast fed for longer than two years in
India, two and a half years in Nepal, and three years in Bangladesh.5
Hundreds of millions of adults currently alive in that region were
probably breast fed for even longer periods than this. If there were
any dose-response, cause and effect relation between sustained
breast feeding and heart disease, why is heart disease not at much
higher levels there among those who reach old age than it is in rich
countries? This study was conducted by a group that included the
Medical Research Council childhood nutrition research centre, which
has collaborated with the infant food industry for its outcome
studies on nutrition. Their honesty in admitting this (or is it the
exemplary BMJ insistence on such declarations?) may not allay
our fears regarding the potential effects on the research of this
kind of conflict of interest
Although Leeson et al point out that their findings cannot be interpreted as
cause and effect, normally anything negatively associated with
breast feeding quickly gets translated into just that by the media
and receives wide dissemination. Let's see what happens with this
one.
Ted Greiner
International Nutrition Research Group, Department of Women's and Children's
Health, Uppsala University, S-75185 Uppsala, Sweden ted.greiner@kbh.uu.se
Competing interests: None declared.
|
1. |
Leeson CPM, Katternhorn M, Deanfield JE, Lucas A. Duration
of breast feeding and arterial distensibility in early adult life: population
based study. BMJ 2001; 322: 643-647 |
|
2. |
Booth I. Does the duration of breast feeding matter? BMJ
2001; 322: 625-626 |
|
3. |
Fall CH, Barker DJP, Osmond C, Winter PD, Clark PM, Hales
CN. Relation of infant feeding to adult serum cholesterol concentration and
death from ischaemic heart disease. BMJ 1992; 304: 801-805 |
|
4. |
Martin J, White A. Infant feeding. London: Office
of Population Censuses and Surveys, 1985. |
|
5. |
Haggerty PA, Rutstein SO. Breastfeeding and
complementary infant feeding, and the postpartum effects of breastfeeding.
Calverton, MD: Macro International, 1999. |
Authors did not
discuss data from prospective studies
Leeson
et al propose a complex mechanism to explain their observations linking a
putative marker of vascular risk with the duration of any breast
feeding.1
They suggest a dose-response relation between duration of any breast
feeding and brachial artery distensibility and that extending breast
feeding by two months has an effect on arterial distensibility
broadly equivalent to that produced by a 4 mm Hg increase in
blood pressure. The discussion of their findings is, however, not
systematic. It neglects (as does the editorial by Booth2) to
review important evidence. The observational findings by Leeson et
al should be placed in the context of other epidemiological data
relating directly to factors (in this case, blood pressure) whose
link to adverse health outcomes are more clearly established than
that of arterial distensibility.
One of the most important pieces of evidence comes from the seven year
follow up by Wilson et al of the Dundee infant feeding study.3 In
this study, systolic blood pressure at the age of 7 was found
to be significantly raised in those children who had been
exclusively formula fed for the first 15 weeks of life compared with
those who had received any breast milk (mean 94.2 (95% confidence interval
93.5 to 94.9) mm Hg v 90.7 (89.9 to 917) mm Hg). These
findings run counter to the observations by Leeson et al on
distensibility, from which the opposite findings would be expectednamely,
that blood pressure would be higher in those children who had been
breast fed. Further evidence against the hypothesis of Leeson et
al comes from the work of Taittonen et al, who found that breast feeding
after 3 months of age was associated with an average reduction in
blood pressure of 6.5 mm Hg.4
We were surprised that Leeson et al did not refer to their own related
research published earlier this year in the Lancet, in which
they concluded that consumption of breast milk was associated with
lower blood pressure at age 13-16 years.5 This
research was based on a unique opportunity afforded by a randomised
trial to overcome some of the biases that are likely to be operating
in observational studies, such as the one they report in your journal.
Jim Sikorski
Department of General Practice and Primary Care, Guy's, King's, and St Thomas's
School of Medicine, London SE11 6SP jim.sikorski@kcl.ac.uk
Carol Dezateux
Department of Paediatric Epidemiology and Biostatistics, Institute of Child
Health, London WC1N 1EH
Competing interests: None declared.
|
1. |
Leeson CPM, Katternhorn M, Deanfield JE, Lucas A. Duration
of breast feeding and arterial distensibility in early adult life: population
based study. BMJ 2001; 322: 643-647 |
|
2. |
Booth I. Does the duration of breast feeding matter? BMJ
2001; 322: 625-626 |
|
3. |
Wilson AC, Stewart Forsyth J, Greene SA, Irvine L, Hau C,
Howie PW. Relation of infant diet to childhood health: seven year follow up
of cohort of children in Dundee infant feeding study. BMJ 1998; 316:
21-25 |
|
4. |
Taittonen L, Nuutinen M, Turtinen J, Uhari M. Prenatal and
postnatal factors in predicting later blood pressure among children:
cardiovascular risk in young Finns. Pediatr Res 1996; 40: 627-632 |
|
5. |
Singhal A, Cole TJ, Lucas A. Early nutrition in preterm
infants and later blood pressure: two cohorts after randomised trials. Lancet
2001; 357: 413-419 |
Does this study
herald the return of national dried milk?
On
the day the article by Leeson et al was published, and because of the national
furore it created, I was asked to generate a response for midwives
to use to allay the worries of mothers telephoning the 24 hour
advice line.1
We work in the wards and departments of a busy obstetric unit in the
north east of England, supporting mothers in the initiation of
breast feeding, but not one mother or any family members queried the
health benefits of breast feeding. People in the north east of
England do watch television and read newspapers, so it seems they
disregarded what they saw as another conflicting message from health
professionals.
We promote breast feeding in areas where there has been a traditional bottle
feeding culture. Articles such as the one by Leeson et al do not
make our work any easier, but I agree with Holmes in her response
that we should not be defensive and that all research should be
scrutinised, even if it does threaten conventional wisdom. I also
agree with other respondents that further, large scale research may
lead to different conclusions. My own local response questions the
statistical methods used and the effects of confounding variables
(such as weaning patterns, definitions of exclusive or partial
breast feeding, etc), which have already been raised by other
respondents. But another issue that should be considered in this
debate is the type of formulas in use during the period studied,
between 1969 and 1975. Before 1974, most types of
formula milk were still comparatively unmodified. Most contained 100%
milk fats, which were difficult for young infants to digest and
absorb. In this area, a large proportion of the population was fed
evaporated milk and national dried milk during this period. Presumably,
although Cambridge is a more affluent area, the formulas available
were still comparatively unmodified.
The 1974 report, Present Day Practice in Infant Feeding (first
report), led to the withdrawal of national dried milk and stated that
all artificial milk should approximate the composition of breast
milk as nearly as is practicable. Formula manufacturers have since
spent many millions (or billions) trying to meet this objective.
Given the time scale, it seems that many of the respondents in the reported
study would have been fed unmodified infant formula. Do the findings
of this study herald the return of national dried milk, as it seems
from this study that these types of formula have benefits over
breast milk? I do not think so; other factors need to be considered.
Anne Holt
South Cleveland, Hospital, University of Teesside, Middlesbrough TS4 3BW anne.holt@tees.ac.uk
Competing interests: Unrepentant mother of four children, all of whom have
been breast fed for over a year; two have been breastfed for over
four years.
|
1. |
Leeson CPM, Katternhorn M, Deanfield JE, Lucas A. Duration
of breast feeding and arterial distensibility in early adult life: population
based study. BMJ 2001; 322: 643-647 |
Breast feeding:
distension or distortion?
It
seems that we live in an increasingly dangerous world: recent media scares have
included calcium channel blockade, the oral contraceptive pill, and,
latterly, long distance air travel. Now it seems that even breast
feeding, promoted for its benefits by our grandparents, is not
without risk, as described by Leeson et al in their paper.1 But
the scientific evidence on which such claims are based varies substantially.
Leeson et al set out to test the hypothesis that breast feeding is
associated with a detrimental reduction in arterial distensibility. Why
they sought to measure distensibility of the brachial artery as an
early marker of cardiovascular disease is unclear. Although they say
that arterial distensibility diminishes with age in relation to
other risk factors, the references they cite concern changes in the
carotid and femoral arteries and aorta, and not, as in their study,
the brachial artery. This is an important distinction: although
aortic distensibility does decrease with age, brachial distensibility
does not change.2
Moreover, despite careful application of the same methods employed
by Leeson et al, others have shown that age and
hypercholesterolaemia do not influence brachial distensibility. 3 4
Although we agree that aortic pulse wave velocity (a measure of
distensibility) does predict cardiovascular outcome in hypertensive
and normotensive people and those with renal disease, we are unaware
of any data suggesting that the same is true of brachial distensibility.
Overall, Leeson et al could not show any difference in brachial
distensibility between those who were breast fed and those who were
not. Brachial pulse pressure, a surrogate measure of large artery
stiffness that predicts outcome, did not differ significantly between
the two groups. There was, however, an inverse association between
the duration of breast feeding and distensibility, but this was
significant only in women. This is surprising since their original
hypothesis was based on the observation that boys who are breast fed
up to 1 year of age have an increased risk of ischaemic heart
disease in later life.5
As a result of the resulting media coverage, many mothers may choose not to
breast feed their infants despite much evidence as to its benefits,
including a reduction in cardiovascular disease in later life, as
noted by Leeson et al. After the pill scare many women stopped
taking the oral contraceptive pill, which resulted in a rise in
unplanned pregnancies. Finally, there is the propensity for the
infant food industry to use such data and media coverage out of
context for commercial benefit.
Ian B Wilkinson
Clinical Pharmacology Unit, University of Cambridge, Addenbrooke's Hospital,
Cambridge CB2 2QQ
John R Cockcroft
Department of Cardiology, Wales Heart Research Institute, University Hospital,
Cardiff CF14 4XN cockcroftjr@cf.ac.uk
Competing interests: None declared.
|
1. |
Leeson CPM, Katternhorn M, Deanfield JE, Lucas A. Duration
of breast feeding and arterial distensibility in early adult life: population
based study. BMJ 2001; 322: 643-647 |
|
2. |
Nichols WW, O'Rourke MF. McDonald's blood flow in
arteries: theoretical, experimental and clinical principles. London:
Arnold, 1998. |
|
3. |
Kool M, Lustermans F, Kragten H, Struijker BH, Hoeks A,
Reneman R, et al. Does lowering of cholesterol levels influence functional
properties of large arteries? Eur J Clin Pharmacol 1995; 48: 217-223 |
|
4. |
Van der Heijden-Spek JJ, Staessen JA, Fagard RH, Hoeks AP,
Boudier HA, van Bortel LM. Effect of age on brachial artery wall properties
differs from the aorta and is gender dependent: a population study. Hypertension
2000; 35: 637-642 |
|
5. |
Fall CH, Barker DJ, Osmond C, Winter PD, Clark PM, Hales
CN. Relation of infant feeding to adult serum cholesterol concentration and
death from ischaemic heart disease. BMJ 1992; 304: 801-805 |
Statistical
analysis was unclear
Leeson
et al, in the conclusions in their paper, seem to rely in part on the
statistical treatment of their limited observational data,1 in
particular, the use of multiple regression analysis and t
tests. Multiple regression was used to determine regression
coefficients as a measure of association between length of breast
feeding and non-invasive brachial artery distensibility. The t
tests were used to test the null hypothesis (presumably) that there
were no differences in brachial artery distensibility between those
who were not breast fed, those who breast fed to age 4 months,
and those who breast fed above age 4 months.
We are uncertain whether the regression analysis incorporated all subjects,
but this is implied in the paper. Therefore, we are presented with a
larger number of those adults who were either breast fed for a short
period or not breast fed at all, and smaller numbers at longer
periods of breast feeding (although numbers are not specifically
given in the paper at each time grouping). We now need to interpret
the regression coefficients (table 3), actually quite broad at the
95% confidence intervals. The paper tells us that the P values
associated with these regressions are just significant, but no
mention is made of the r2 values that will tell us how much
of the variability of arterial distensibility is explained by all
variables, including duration of breast feeding. Furthermore, there
seems to be no analysis of adults who had been breast fed alone and
no r2 value.
In addition, for the dichotomised groups, arterial distensibility is
compared (t test) with the non-breastfed group, and a similar
comparison is made between the dichotomised groups. Although two
comparisons are reported, we suggest that these sort of comparisons should
be conducted by using one way analysis of variance with appropriate
testing afterwards (for example, Bonferroni), or if multiple t
tests are used, then the level of significance (presumably set at
P=0.05 here) should be reduced to account for multiple comparisons
(we suggest three comparisons in this case). The low level of
significance reported between the dichotomised groups (P=0.02) is
unlikely to survive such conservative statistical treatment. These
approaches are more conservative but give us greater confidence in
the assertion that some arbitrarily determined time point could be
important in determining future risk of cardiovascular disease.
We find little in this paper that will change our current personal habits or
advice we give to other parents. We are delighted that the authors
agree.
Paul Michael Dark
Emergency and Intensive Care Medicine, University of Manchester, Manchester Paul.M.Dark@man.ac.uk
Marie-Josée Rölli
Greenmount Medical Centre, Bury BL8 4DR
Competing interests: Parents of breastfed infants and children. M-JR is a
member of the breastfeeding network.
|
1. |
Leeson CPM, Katternhorn M, Deanfield JE, Lucas A. Duration
of breast feeding and arterial distensibility in early adult life: population
based study. BMJ 2001; 322: 643-647 |
Authors' reply
Our
paper on the duration of breast feeding and later arterial distensibility
evoked much comment, especially from those who promote breast
feeding. Unfortunately the media coverage may have deflected
attention from the cautious way we framed our findingsand
our clear recommendation that they should not change breastfeeding
practice.
Some cast doubt on our work by implying that it was motivated or influenced
by formula milk companies. This is certainly not so. The study was
funded by the Medical Research Council and the university, with no
industrial connection whatsoever. Our childhood nutrition centre is
core funded by the government (MRC). Our longstanding research
includes some of the strongest scientific evidence available favouring
breast feeding, in terms of its beneficial effects on cognitive
development, blood pressure, bone health, atopic disease, infection,
gut disease, and catch-up growth 1 2 evidence
much used by professional organisations that support breast feeding.
We have also researched the efficacy and safety of new advances in
infant formula milks and, for transparency, cite this in our article.
As an independent centre we publish what we find in the interests of
public health, quite regardless of any pressures from either
industry or advocacy groups.
Our findings have clearly seemed counterintuitive to many. Dettwyler cites
an anthropological argument based on primate work, that humans were
evolved to breast-feed for two and a half to seven years, as
evidence that our results are biologically implausible. Life span
was, however, much shorter when human lactation evolved, and we
cannot assume that breast feeding, through past evolution, would now
confer any advantage in terms of reduced adult degenerative disease
or postreproductive survival. Nor can we assume that breast feeding
evolved such that humans would necessarily be well adapted to a
modern Western style post-weaning diet. Holmes affirms this view.
Our paper has stimulated comment on interpretation and methods. We agree
with Greiner that it is difficult to interpret non-randomised outcome
studies on breastfed infants, which of course also applies to the
extensive and potentially confounded literature purporting to show
benefits of breast feeding. This centre has been one of the only
ones to conduct large scale randomised studies on breast milk versus
formula in a circumstance in which this is ethicalin
non-breastfed premature infants who can be assigned randomly to formula
milk or donated banked breast milk. These few studies provide
experimental evidence for long term effects of breast milk on health
outcomes.1
When randomisation is precluded (as, say, with smoking), however,
causation must be established from a weight of epidemiological
evidence, supported by animal experiments. We appraised the possible
significance of our own data in such a context, although we accept
that the research is at an early stage.
Some respondents imply that we were directly comparing formula feeding to
breast feeding. This was not our intention. As Holt noted, formula
milks used in the 1970s were different from those currently
available, and study of formula fed subjects in our cohort would
have had little contemporary relevance. In epidemiological and
intervention studies, breast feeding seems to confer cardiovascular benefit
over formula feeding.1 Our
interest focused solely on the duration of breast feeding in
relation to vascular health in a Western population, in view of
previous work we reference.
Our paper considers carefully our surrogate marker of arterial disease,
brachial artery distensibility. Wilkinson and Cockroft note that
much work on distensibility has been based on the widely used aortic
pulse wave velocity. Oddly, their response entirely ignores more
recent studies, including this paper, which consistently show an
association between peripheral artery distensibility and concentrations
of cholesteroland
that the various methods for measuring distensibility in central and
peripheral arteries are well intercorrelated.3-6
Simple non-invasive vascular measures, as used in our study, provide
unique opportunities to investigate early stages of disease development.
We used a statistically robust approach to data analysis and have been
appropriately cautious in our interpretation, taking account of cohort
size and significance level. We would reassure Dark and Rölli that
the relation between breastfeeding duration and arterial
distensibility persists whether analysis is performed on the entire
cohort or solely on those breast fed. The r2 for distensibility
versus length of breast feeding is 0.22, suggesting the model
accounts for around a quarter of the variability in distensibility.
Finally, we wish to re-emphasise why we would not suggest any current change
in breast feeding practice. Firstly, our data are at too early a
stage to be translated into health policy. Secondly, any
risk-benefit analysis must include the many positive purported
benefits of breast feeding on short and long term outcome.
If the hypothesis we raised proves correct, that more prolonged
breastfeeding duration followed by a Western style diet explains our
results, then future intervention policy might be better directed to
our Western diet rather than breast feeding. We hope that the complex
social issues that surround this subject will not cloud the need for
dispassionate research to optimise infant nutrition in relation to
long term health.
Paul Leeson
Alan Lucas
Medical Research Council Childhood Nutrition Research Centre, Institute of
Child Health, London WC1N 1EH
Competing interests: The centre has collaborated with the infant food
industry for its outcome studies on nutrition.
|
1. |
Singhal A, Cole TJ, Lucas A. Early nutrition in preterm
infants and later blood pressure: two cohorts after randomised trials. Lancet
2001; 357: 413-419 |
|
2. |
Lucas A, Morley RM, Cole TJ, Lister G, Leeson-Payne C.
Breast milk and subsequent intelligence quotient in children born preterm. Lancet
1992; 339: 261-264 |
|
3. |
Leeson CP, Whincup PH, Cook DG, Mullen MJ, Donald AF,
Seymour CA, et al. Cholesterol and arterial distensibility in the first
decade of life: a population-based study. Circulation 2000; 101:
1533-1538 |
|
4. |
Giannattasio C, Mangoni AA, Failla M, Carugo S, Stella ML,
Stefanoni P, et al. Impaired radial artery compliance in normotensive
subjects with familial hypercholesterolaemia. Atherosclerosis 1996;
124: 249-260 |
|
5. |
Shiage H, Dart A, Nestel P. Simvastatin improves arterial
compliance in the lower limb but not in the aorta. Atherosclerosis
2001; 155: 245-250 |
|
6. |
Liang YL, Teede H, Kotsopoulos D, Shiel L, Cameron JD,
Dart AM, et al. Non-invasive measurements of arterial structure and function:
repeatability, interrelationships and trial sample size. Clin Sci
1998; 95: 669-679 |
Summary of
rapid responses
All but five of the responses were highly critical of the paper, largely for
shortcomings in the methods and because it was funded by a
manufacturer of formula milk. Others were concerned about the
negative effects on breast feeding resulting from the media's
treatment of the results.
Luis Gabriel Cuervo, a member of the BMJ's editorial board, roundly
criticised the BMJ in its management of the paper:
"The BMJ has a responsibility not only to publish evidence. It
also has to foresee the effect of the published paper on global health
and clearly address it. The breach that allowed the media to
manipulate the results and jump to the conclusion that breast feeding
for more than four months causes cardiovascular disease is
inadmissible and will surely be commercially exploited for unscrupulous
purposes, here and in the developing world, with terrible
consequences. Later explanatory letters may not have the same impact
in the media and may not compensate for the damage that has been
done."
Three lone voices joined the authors' in the wilderness.
Allan Astrup Jensen, research director of a company in Denmark, thought that
"the many critical responses try to kill the messenger because
the message is unpleasant and may hurt common health policies. No
paper is perfect, including this one. There will always be questions
raised and criticism of methods, execution, and reporting."
Andrew Mimnagh, a general practitioner, and Timothy James, a university
senior lecturer, were concerned about the demand by some respondents
to ban research sponsored by companies as unethical. Mimnagh added:
"I agree the finding is counterintuitive but so are many
`proven facts' in the natural world."
James was disturbed by the "low level of logic" in some of the
responses: "[It seems that] the answer has been predetermined and
only evidence that supports that answer is acceptable. This is
contrary to the entire scientific approach to truth seeking, which
demands that we go wherever the evidence takes us, whether it is
where we wanted to go or not." He concludes that drawing "conclusions
for our own environment is a complex multifactorial matter, which
cannot be summed up in a simple slogan like `breast is best'however
unethical the behaviour of sellers of breast milk substitutes."
Sharon Davies
BMJ
|
1. |
Electronic responses. Duration of breast feeding and
arterial distensibility in early adult life: population based study. bmj.com
2001;322 (http://bmj.com/cgi/eletters/322/7287/643;
accessed 13 Sep 2001). |
|
2. |
Electronic responses. Does the duration of breast feeding
matter? bmj.com 2001;322 (http://bmj.com/cgi/eletters/322/7287/625;
accessed 13 Sep 2001). |
|
Other related articles in
BMJ:
PAPERS
Duration of breast feeding and arterial distensibility in early adult
life: population based study.
C P M Leeson, M Kattenhorn, J E
Deanfield, and A Lucas
BMJ 2001 322: 643-647.
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