The first-of-its-kind observational study — conducted by the New Zealand Institute for Plant and Food Research and funded by Danone Nutricia — saw the researchers analyse the dietary intakes and breastmilk nutrient composition of 78 breastfeeding women between the ages of 19 and 42.
The women were living in New Zealand's North Island region of Manawatu-Wanganui, and the study population was representative of the national ethnic composition: 53 (68%) were of European descent, 17 (22%) were Māori and / or from the Pacific Islands, and eight (10%) were Asian.
They each provided three breastmilk samples over a one-week period — six to eight weeks after having given birth — completed a three-day food diary, and volunteered information on their pregnancy and lactation experiences.
The researchers then analysed the breastmilk samples for protein, fat, fatty acid profile, carbohydrates, ash, and minerals (calcium, magnesium, selenium and zinc).
Subsequently, the researchers reported that, perhaps due to differences in culturally influenced dietary patterns and lifestyle factors, the concentrations of certain nutrients varied considerably among the ethnic groups.
The Māori / Pacific Island mothers consumed less protein than the European mothers, while the Asian mothers consumed less energy and a lower proportion of fat from saturated fat than the other mothers.
Instead, a significantly higher proportion of the Asian mothers' total fat intake came from monounsaturated fats, and they consumed more PUFAs than the European mothers, who tended to consume more calcium, phosphorus and zinc than the other mothers.
The Asian mothers also consumed the most iodine, folate, and vitamin A equivalents than the rest of the mothers.
The European women had lower concentrations of omega-3, omega-6, polyunsaturated fatty acids (PUFAs), EPA, DHA and ALA (alpha-linoleic acid) in their breastmilk than the Asian women, but higher concentrations of ARA (arachidonic acid) and magnesium than the Māori / Pacific Island women.
The Asian women had higher concentrations of all the aforementioned nutrients than their European and Māori / Pacific Island counterparts, the latter of whom had the lowest concentrations of these nutrients among the three ethnic groups.
However, regardless of the degree of dietary diversity across the different ethnic groups, all the mothers had similar amounts of the main macronutrients in their breastmilk, namely, protein, fat, and carbohydrates.
There were also no significant differences between the mean breastmilk concentrations of calcium, selenium and zinc across the groups, or in ARA between the Asian and European mothers.
DHA and ARA are particularly beneficial for brain, neural and eye development in infants.
Speaking to NutraIngredients-Asia, Dr Christine Butts, team leader at Plant and Food Research, offered a possible explanation for the similarity in the breastmilk levels of main micronutrients across the different groups.
"We didn't do an extensive study beyond the mothers' diets when it came to determining which factors influenced the nutrient composition in their breastmilk.
"However, I do think that the mothers' breastmilk providing these essential micronutrients for their babies, regardless of their diet, is a great example of the human body simply being amazing."
Still, Butts emphasised the importance of adequate nutrition for both mother and child, saying, "New Zealanders tend to have low selenium, iodine and folate intakes. Breastfeeding mothers should ensure they have adequate nutritional intake, as this directly affects the health of their babies.
"I would propose that they work hard on their diet and nutrition, engaging professional nutritionists and / or dietitians if possible to guide them and point them in the right direction. Dietary supplements can also be very useful to breastfeeding mothers."
Apart from conducting scientific studies like this one, the NZ Institute for Plant and Food Research is also a member of the Nutrition Society of New Zealand (NSNZ), a non-profit focused on furthering nutrition as a scientific field.
The NSNZ facilitates collaborations among professionals in different areas of nutrition— such as human and animal nutrition — and according to Butts, Plant and Food Research and the NSNZ work cooperate periodically on such projects.
She believes this particular study will be able to provide useful data to analyses on a larger scale in the future, and may even help manufacturers to develop not just dietary supplements and functional foods, but also personalised nutrition programmes to support the health of breastfeeding mothers and therefore, their babies as well.