A Comparative Study of Infant Formulas and Human Milk: Exploring the Impact of Cow's Milk Consumption on Beneficial Fatty Acids as trans-vaccenic (trans-C18:1 n-7) in Breast Milk

Maternal diet plays a significant role in the fatty acid composition of breast milk. Natural trans fatty acids (TFAs) are generated through the biohydrogenation of unsaturated fatty acids (FAs) in the rumen of animals by bacterial isomerases and are consequently found in milk, dairy products, and meat from ruminant animals. Dietary products such as milk and meat are the primary sources of natural TFAs for humans, derived from rumen fermentations. These peculiar fatty acids hold nutritional significance as they not only lack the detrimental effects on endothelium characteristic of industrially produced trans fat, but also exhibit anti-inflammatory properties. The relationship between the presence in breast milk of eight fatty acids (including natural TFAs trans-vaccenic and conjugated linoleic acid) and maternal diet has been explored, and their abundance has been compared to that of infant formulas. Two cohorts of lactating women participated in this study, originating from a Spanish region adhered to the Southern European Atlantic Diet or Atlantic Diet. While the consumption of conventional meat or dairy products does not seem to increase the abundance of trans fatty acids in breast milk, trans-vaccenic and oleic acid are among the most distinctive features of breast milk fat in mothers consuming naturally improved dairy products, with an improved fatty acid profile. The most significant differences between natural breastfeeding and formula feeding lie in natural trans fatty acids, since formula are notably deficient, while overfortified in alpha-linolenic acid in comparison to breast milk.