Summary: Comparison of bovine milk fat and vegetable fat for infant formula: Implications for infant health

This summary has been adapted from "Jeske H.J. Hageman, Marianne Danielsen, Arie G. Nieuwenhuizen, Anouk L. Feitsma, Trine K. Dalsgaard, Comparison of bovine milk fat and vegetable fat for infant formula: Implications for infant health, International Dairy Journal, (2019)"

What this means for Kendamil: This study indicates that the structure and function of bovine milk fats is superior to vegetable oils, as demonstrated by clinical trials. Kendamil is the only infant formula in the UK that uses natural bovine fats from whole milk.

Human breast milk contains many components that lead to healthy infant growth and development, thus it can be assumed that infant formula that closely resembles human breast milk will be better for the development of the baby overall. One of the factors in human breast milk that is so nutritious for a baby is its fatty content. 4% of human breast milk consists of fat, of which 50% is used as energy by infants¹. This fat is found in globules, which are filled with triglycerides. Triglycerides are structures with a glycerol backbone and three fatty acids. By understanding the types and variety of triglycerides in human breast milk, we can better develop infant formulas. Image from: Alfieri, A., Imperlini, E., Nigro, E., Vitucci, D., Orrù, S., Daniele, A., Buono, P. and Mancini, A., 2018. Effects of plant oil interesterified triacylglycerols on lipemia and human health. International journal of molecular sciences, 19(1), p.104. Image from: Kanso, MCT fats for long-chain fatty acid oxidation disorders < https://www.kanso.com/en/a/mtc-fats-oxidation-disorders> All infant formulas currently on the market contain fats as they are understood to be essential to an infant’s growth and development. However, these formulas are substituted with vegetable fats, including palm oil, coconut oil, corn oil, soybean oil, sunflower oil high oleic safflower oil and rapeseed oil². There are many differences between vegetable fats and human milk fats. Human milk fat contains 200 different fatty acids³, ranging from a chain length of 4 to 26 carbons in length, while the fatty acids in vegetable fats have less variety, with fatty acid chains ranging from 4 carbon chains to 12 carbon chains³, and an absence of fatty acids containing an odd number of carbon chain. In addition to chain length difference, the prevalence of long chain fatty acids (LCFAs), medium chain fatty acid(MCFAs) and short chain fatty acids (SCFAs) differs in milk fats and vegetable fats. In human milk fats, LCFAs make up 98% of fatty acids, MCFA comprises 2% of fatty acids and SCFAs including butyrate are found in minute amounts. In vegetable fats, there are lower levels of MCFAs and butyrates, and higher levels of monounsaturated fatty acids. The prevalent triacylglycerol structures in human milk fats are different from those found in vegetable fats. In human milk fat, most palmitic acids (16:0) are situated in the Sn-2 position. However, in vegetable fats, high levels of palmitic acids are found in the Sn-1 and Sn-3 positions⁴. Another difference between these fats is clear when comparing the levels of cholesterol present, in human milk, Cholesterol makes up 0.3% of the fat content and is present at 90-150mg/L², whereas Cholesterol in infant formulas made using only vegetable fats is found at levels of 0-4mg/L⁶. In contrast to vegetable oils, bovine milk fat resembles human milk fat much more closely, for example, the fat in bovine milk contains 400 fatty acids, of which 90% are LCFAs. The main fatty acids present in bovine milk are oleic and palmitic acids. In human breast milk, palmitic acids are 10% of an infant’s energy intake⁷. Similar to human milk, bovine milk fat primarily contains palmitic acid in the SN-2 position and oleic acid in the SN-1 or SN-3 positions. The importance of the positioning of palmitic acid will be explored later. Bovine milk also contains higher levels of Cholesterol (300mg/L)³. This is important because while Cholesterol should be avoided in adults, Cholesterol is an indispensable building block for all cell membranes and is incorporated in considerable amounts into myelin in the nervous system during the period of rapid brain growth early in life⁶. Though bovine milk boasts all these similarities, there are differences. These include higher levels of saturated fatty acids in bovine milk than human milk fat and only 1.5% of the fatty acids are linoleic acid, compared to 15% in humans. The vast difference in composition of vegetable fats compared to human milk fat has implications on infant’s health, for instance, calcium soap forms in infants fed with infant formulas based on vegetable oils because the palmitic acids that are found in the SN-2 positions in human milk fat, are in the SN-1 and SN-3 positions in vegetable fats⁷. SN-1 and SN-3 positions are subject to lipase reactions, causing them to be removed from the glycerol backbone and freely float in the lumen, once in the lumen, these long-chain fatty acids combine with calcium ions forming soaps⁸. These soaps are insoluble, and therefore, neither the palmitic acid nor the calcium are absorbed. The effects of these soaps in the infant's intestine include constipation, stool hardness and reduced bone mineralization⁹. Another cause for concern is the lack of Cholesterol in vegetable fats. Cholesterol is important in the development of infants from brain maturation to the production of bile acids and steroid hormones. It has been shown that breastfed infants have an advantage over formula-fed infants when measuring cognitive function¹⁰. A lack of Cholesterol, as well as triglyceride diversity, could contribute to this loss of cognitive function¹⁰. Bovine milk fat more closely resembles human milk fat when compared to vegetable fats. This has been shown to be clinically meaningful as enriching infant formula with bovine lipid components improves the cognitive score of infants¹¹. References

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