Breastfeeding has evolved to keep human genes in the gene pool. From that perspective, until extremely recently, breastfeeding failure nearly always resulted in a failure for the genes involved to remain in the pool. Thus, not surprisingly, true lactation failure is rare. While it is true that breastfeeding sometimes is difficult or untenable for some individual women, let us lay the blame for this where it belongs--on society. Efforts to protect, support, and normalize breastfeeding in society must come before and receive higher priority than efforts to promote it to or pressure individual women. Individual women need expert assistance with lactation management when problems occur, as well as sympathy and moral support when breastfeeding is difficult or it proves challenging for women to fit into their lifestyles. But the solution is never to "let ourselves off the hook" by simply recommending infant formula.

Breastfeeding has evolved to keep human genes in the gene pool. From that perspective, until extremely recently, breastfeeding failure nearly always resulted in a failure for the genes involved to remain in the pool. Thus, not surprisingly, true lactation failure is rare. While it is true that breastfeeding sometimes is difficult or untenable for some individual women, let us lay the blame for this where it belongs--on society. Efforts to protect, support, and normalize breastfeeding in society must come before and receive higher priority than efforts to promote it to or pressure individual women. Individual women need expert assistance with lactation management when problems occur, as well as sympathy and moral support when breastfeeding is difficult or it proves challenging for women to fit into their lifestyles. But the solution is never to "let ourselves off the hook" by simply recommending infant formula.

"Breastfeeding has evolved to keep human genes in the gene pool. From that perspective, until extremely recently, breastfeeding failure nearly always resulted in a failure for the genes involved to remain in the pool".

Since it was the fitter, healthier, and more competent mothers who were able to keep their infants alive, there has been massive selective dumping of less fit genomes from the gene pool along with the dead babies. I think this positive feedback mechanism is sufficient to explain the evolutionary increase in human intelligence.

To say "best" is hardly overstating. In fact, this is the only statement many women have heard, and they have not heard any details about specific medical outcomes that may be important to them. Regardless of the extent of discrepancy between infants exposed to this norm, and infants exposed to the intervention that is formula feeding, I know of no situation where, at a population level, breastfeeding is a worse method of infant feeding than the available alternatives.

At an individual level (I would be very cautious about approaches to "Certain groups" of women) each woman needs targeted information and support, depending on her circumstances.

Health promotion is about opportunity not about blame.

"I know of no situation where, at a population level, breastfeeding is a worse method of infant feeding than the available alternatives."

Prolonged breastfeeding, for over a year, is a strong risk factor for malnutrition and dental caries.

In the case of malnutrition, this is not correct. It is a case of reverse causation. Mothers whose children are small, sickly or malnourished for whatever reason continue breastfeeding them longer. Mothers with strong, healthy children decide at an earlier age that it is safe to stop breastfeeding them. See Association of breastfeeding and stunting in Peruvian toddlers: an example of reverse causality.

Marquis GS, Habicht JP, Lanata CF, Black RE, Rasmussen KM.

Int J Epidemiol. 1997 Apr;26(2):349-56.

Regarding cavities, I believe that at least part of the explanation is that mothers hide extended breastfeeding from health workers. In much of the North it is stigmatized. So when they are healthy with healthy teeth no one knows it is going on. When there is caries, the truth comes out. That's a poor quality "risk factor." Bottle feeding is a much clearer risk factor, especially when its contents include sucrose or fruit juice. While there may be a very small effect, if breastfeeding for longer than a year is an important risk for caries, in a country like Bangladesh say (where half the population was breast fed for over 3.5 years) caries would be a much more serious problem than in say South Pacific islands where breastfeeding is short but caries rampant.

It is not breastfeeding per se or breastmilk that leads to dental caries, but prolonged breastfeeding in bed at night, a convenient way to feed an older infant. The infant will often be fed on its back, so that milk may pool in the mouth round the teeth and rot them. This is the same mechanism as for bottle feeding caries. It is more important to check how infants are being fed, rather than to worry about what is fed.

Please provide your research evidence for your statement that "Prolonged breastfeeding, for over a year, is a strong risk factor for malnutrition and dental caries." A systematic review showed no clear relationship between breastfeeding and early childhood caries when confounding factors such as fluoride, diet, hygiene practices etc are considered. White V. Evid Based Dent 2008; Salone LR et al JADA 2013. Even if there was a strong association with bf over a year and dental caries, would it be preferable to have an unhealthy child with no caries or a healthy child with some caries? There are so many strong research based studies on the health importance of breastfeeding I couldn't begin to cite them. Malnutrition - on the contrary, there is strong evidence for malnutrition from not breastfeeding or short duration of breastfeeding. Remember mal-nutrition encompasses bot under and over nutrition.

"There are so many strong research based studies on the health importance of breastfeeding I couldn't begin to cite them."

No need to, I quite agree, though I wouldn't frame the question in this way. Breastfeeding is the natural default option, it should not be necessary to produce any evidence to support it. The problem is with many of the alternatives to breastfeeding. It is like saying exercise is good for you, when the problem is with those who exercise less than nature intended.

"Malnutrition - on the contrary, there is strong evidence for malnutrition from not breastfeeding or short duration of breastfeeding."

Agreed. The problem with the breastfeeding literature is that virtually all of it, especially recent studies, is that it deals mainly with the first 9 months of life. I will, however, go and dig up what data there is on prolonged breastfeeding.

Anthony - your statement was related to dental caries - any research to support your statement breastfeeding is a strong risk factor?

I totally agree breastfeeding is the norm and should not need to prove it - you are the person who raised the issue that maintaining this biological norm someway became a risk factor after a certain number of months. The biologically natural weaning age is well over 2 years for humans. I await with interest what you find to support your statement about "prolonged" breastfeeding and risk.

"any research to support your statement breastfeeding is a strong risk factor?"

See this abstract for a start. I think the causal factor is breastfeeding in bed, so that milk pools around the teeth. There are other papers on positional caries in bottle-fed infants illustrating the same process, which I am now going to look up.

Dental caries and prolonged breast-feeding in 18-month-old Swedish children

A.-L. HALLONSTEN et al

Article first published online: 24 APR 2009

DOI: 10.1111/j.1365-263X.1995.tb00298.x

International Journal of Paediatric Dentistry

Volume 5, Issue 3, pages 149–155, September 1995

Summary. Three thousand children aged 18 months were screened for dental caries and ongoing breast-feeding at 46 child welfare centres in different parts of Sweden. Of these, 200 children were selected for a more comprehensive examination, involving investigation of dietary, toothbrushing and sucking habits, use of fluoride, and determination of salivary levels of mutans streptococci and lactobacilli. The children were divided into four groups: group 1: children with caries not being breast-fed; group 2: children with caries being breast-fed; group 3: caries-free children being breast-fed; group 4: caries-free gender- and age-matched reference children not being breast-fed. The results showed that 63 of the children (2.1%) had caries and 61 (2.0%) were still being breast-fed. Twelve (19.7%) of the 61 children still being breast-fed had caries compared with 51 (1.7%) of the 2939 children not being breast-fed; the difference was statistically significant. Children with caries and still being breast-fed had a mean defs of 5.3, and those with caries not being breast-fed 4.9; the difference was not statistically significant. Children with caries, irrespective of whether they were being breast-fed or not, had significantly higher numbers of cariogenic food intakes per day than caries-free children. Mutans streptococci were detected in 67% of the children and lactobacilli in 13%. Children with detectable mutans streptococci and lactobacilli had significantly more caries than those without. The results indicate that Swedish children with prolonged breast-feeding have a tendency to establish unsuitable dietary habits which constitutes a risk situation for developing caries at an early age.

This is the first article I have found, but there are many more if needed:

Caries Res. 1998;32(1):46-50.

Prolonged demand breast-feeding and nursing caries.

Weerheijm KL1, Uyttendaele-Speybrouck BF, Euwe HC, Groen HJ.

Abstract

The aim of this study was to study the characteristics and to explore risk factors within a group of Dutch children breast-fed on demand over a prolonged period, whose mothers attended the meetings of La Leche League. Ninety-six children, 55 boys and 41 girls (mean age 28.8 months, SD 8.8), were examined. Most of the parents belong to a higher socio-economic working class. The examination included a questionnaire and dietary sheet, combined with the caries status of the child. On average the children were breast-feed for 21.5 months (SD 9.8). The mean age at which the parents started brushing the children's teeth was 11.7 months (SD 5.1). Fluoridated toothpaste (250 ppm fluoride) was used by 70% of the children. The children were divided into three groups according to their caries pattern: 1 caries-free; 2 caries, and 3 nursing caries. Dentine caries was found in 14 (14.5%) of the children, of which 9 (9.3%) met the criteria of nursing caries. The mean dmfs of all children examined was 1.2 (SD 4.8). Up to 18 months of age the breast was given significantly more frequently during the night and up to 24 months during the day time, to the children of the nursing caries group compared to the children in the other two groups. The children still being breast-fed at the time of investigation more frequently slept in their parents' bed. The children of the nursing-caries group used fluoridated dentifrices less often. The majority of children of the caries and nursing-caries groups did not receive fluoride from other sources. The results of the present study demonstrate that prolonged demand breast-feeding does not lead to a higher caries prevalence although comparison between the groups demonstrates that frequent breast-feeding and low additional fluoride use should be considered as contributing factors in the process of nursing caries.

Anthony, the problem with these studies and other studie from that period and before, is what they didn't investigate.

1) Oral bacteria. The strength oif the first study you cited, Anthony (the one published in 1995 and then online in 2009), is that it measured levels of mutans streptococci, but this doesn't seem to have been investigated in the Dutch study. It would be useful if the studies had asked respondents about mouth kissing and sharing of spoons - and the consequent sharing of maternal oral bacteria leading to dental caries. I see this as a more important question than use of fluoride. On-the-mouth kissing and the sharing of implements such as spoons is something that future studies should investigate.

2) Gasgtro-oesophageal reflux. What is notably absent from most, possibly all, studies of this topic is investigation for gastro-oesophageal  reflux (GOR / GER), including "silent reflux".  Two factors should make this an essential investigation: 1) that more acid is secreted in the stomach to digest food and 2) lying down prevents gravity from keeping any refluxed acid in the stomach. There have been studies of dental caries in adults with GOR, leading to erosion of the molars, but this possibility in young children seems to have been ignored. Management of the feeding or post-feeding position to allow gravity to enable any regurgitated acid to drain would be worth investigating.

The second problem with these early studies is that some of them don't take into account what is today known about the mechanism of sucklihng at the breast, which differs from sucking on various types of bottles. Bottles from this period were likely to drip, unless empty. The breast is elongated to form a "teat" with the nipple during active breastfeeding, and thus the milk sprays out at the back of the mouth ready for swallowing. It thus don't pool in the mouth - it would have to be brought forward to do so!  When the child stops drinking from the breast, it shrinks back to its resting shape and assumes a different position in the child's mouth. At the end of a feed and at this late stage of lactation, it is unlikely to drip.

I hope this analysis is useful.