(Also -- Read my post about Protein HERE)
There is overwhelming evidence that a whole-foods vegan diet has many benefits throughout the lifespan. One benefit in particular, is that eating lower on the food chain (ie just plants) reduces one's exposure to pesticide residues and toxic chemicals like mercury and DDT. This is particularly important when it comes to pregnancy and lactation, since some environmental contaminants can impair neurological development, alter immune responses and even increase the risk of cancers. I have been vegan since before conception of my two now grown-up life-long vegan daughters, both of whom are grateful that we raised them as vegans. A diet emphasizing beans, and greens with fruit, other vegetables and small amounts of raw nuts and seeds is the basis for optimum health. Pregnant and nursing mothers, eating a whole foods plant based diet, and taking sublingual B-12, vegan D3 (if they aren’t getting daily sun) and an algae based DHA/EPA supplement give their breastfed babies superior nutrition, while minimizing exposure to pesticides, and heavy metals. This will benefit brain function and reduce the likelihood that their children will ever develop many of our most common chronic diseases, like Diabetes, Asthma, Coronary Artery Disease, Kidney Disease and Breast and Prostate Cancer to name a few!
Although very little research has actually been published that compares levels of breast milk contaminants between long-term vegans and omnivores, in 1971 the New England Journal of Medicine published an account of a small study which did find the breast milk of vegans was lower than that of omnivores, and stated that in every single contaminant measured, the highest levels in the vegans was lower than the lowest level in the omnivores:
Pollutants in breast milk of vegetarians.
It would make sense for this to be the case, since basic biological principals show that there is bio accumulation of environmental toxins as one moves up the food chain, and humans eating an omnivorous diet essentially sit at the top of the food chain – with their breast-fed babies being at the very top. Together, the studies linked to below suggest that complete avoidance of meat, dairy, eggs and fish -- especially the longer this can be done would likely contribute to having breast milk that is lower in most major environmental contaminants, since the highest dietary sources of two of the more common and clearly harmful toxins, DDT and PCB’s are animal and fatty foods: http://www.watoxics.org/chemicals-of-concern/pcbs-and-ddt
However the following study clarifies the issue a bit more as it suggests that fat from plant sources is NOT associated with breast milk contamination – unlike fats from ANIMAL foods:
Relationship of dietary intake to DDE residues in breast milk of nursing mothers in Beirut.
A study that took place in Ireland looked at a specific class of toxic compounds, similar to dioxins, which appear to be ubiquitous in the environment. They tested 100 different types of foods and reported that dairy products, fish, meat and eggs were the largest sources of dietary exposure to these toxic compounds:
Polychlorinated naphthalenes (PCNs) in Irish foods: Occurrence and human dietary exposure
Breast milk from The Netherlands was far more contaminated than breastmilk from Hong Kong – In spite of Hong Kong being more industrialized. I would expect that this reflects differences in consumption meat and dairy between the two populations.
Comparison of dioxin and PCB concentrations in human breast milk samples from Hong Kong and the Netherlands.
This study, sought to show that pesticide residues in organic goat milk was within safe ranges, but the more important point I see here is that the levels were as high as they were, given that the animals were being fed only organic foods. This demonstrates the idea of bioaccumulation. When you eat animals you are eating their lifetime exposure environmental toxins, and some of those toxins are excreted into their milk.
Assessment of health risk from organochlorine xenobiotics in goat milk for consumers in Poland.
This study found positive associations between egg eating (in addition to meat and fish) and dioxin concentration in human breast milk.
Maternal risk factors associated with increased dioxin concentrations in breast milk in a hot spot of dioxin contamination in Vietnam
And these may be of interest too:
Assessing infant exposure to persistent organic pollutants via dietary intake in Australia.
Organochlorine pesticides residue in breast milk: a systematic review.
This study’s data suggests that concentrations of pesticides in a breastfed baby may be even higher than what is found in mother.
A novel model to characterize postnatal exposure to lipophilic environmental toxicants and application in the study of hexachlorobenzene and infant growth.
At first glance, this study appears to suggest that fish consumption is the only dietary factor linked with increased contaminants in breast milk. However, when you consider that this study had only 125 participants, and given the tendency for homogeneity of diets regionally in Japan, it is likely that there were few if any women in the study even eating a plant based diet for comparison -- certainly not enough to allow for statistical significance if differences were found. A classic example of the “sick population” bias rampant in many nutrition studies.
Maternal body burden of organochlorine pesticides and dioxins.
All the women in this study had multiply contaminated milk and all of them ate a similar omnivorous diet including meat, dairy and eggs.
Dioxins and furans in breast milk: a case study of mothers from southern Rio de Janeiro, Brazil
Here's a really great article seeking to explore risks vs benefits of breastfeeding vs formula in light of the fact that humans sit at the top of the food chain (but not vegans!) Lots of good information about benefits of breast milk!
Contaminants in Human Milk: Weighing the Risks against the Benefits of Breastfeeding
Dr Kradijan’s “MILK LETTER” written to his patients is very good:
Finally, I'd like to leave you with this to think about. I still think of myself as a "nursing mother". The memory of the intense feelings of love and attachment that I felt as my babies nursed is still profound. I realized then, that much of what I thought of as, "LOVE" for my children was very hormone driven. Each time my milk flowed, I'd have an even more overwhelming desire to be with my babies. It would have been very upsetting if someone had tried to interfere in my ability to nurse and care for them -- and even worse if someone had actually taken them from me! I know that I share that feeling with lactating females all over the world -- including those of non-human mothers. When I see someone eating cheese or drinking cow's milk, I cannot help but feel sad for the cow mother who had her baby stolen from her so that humans could take the milk she made for her baby. That is one of the most compelling reasons why I remain vegan.