Is increased fat content of hindmilk due to the size or the number of milk fat globules?

BackgroundIt is known that the fat content of breast milk is higher in hindmilk than in foremilk. However, it has not been determined if this increased fat content results from an increase in the number of milk fat globules (MFGs), an increase in the size of MFGs, or both. This study aims to determine which factor plays the most important role.MethodsThirteen breastfeeding mothers were enrolled in the study and we obtained 52 samples from 26 breasts before (foremilk) and after (hindmilk) a breastfeeding session. The fat content was evaluated by creamatocrit (CrCt) values. MFG size was measured with the laser light scattering method. We compared CrCt values and MFG size between foremilk and hindmilk.ResultsAlthough the CrCt values were higher in the hindmilk (8.6 ± 3.6%) than in the foremilk (3.7 ± 1.7%), the MFG size did not change (4.2 ± 1.0 μm and 4.6 ± 2.1 μm, foremilk and hindmilk, respectively). There was no relationship between the changes in CrCt versus MFG size from foremilk to hindmilk.ConclusionThe results indicate that the increase in fat content results mainly from the increased number of MFGs, which may be released into the milk flow as the mammary lobe becomes progressively emptied.

[1]  V. Briard-Bion,et al.  Microfiltration of raw whole milk to select fractions with different fat globule size distributions: process optimization and analysis. , 2006, Journal of dairy science.

[2]  M. Michalski,et al.  Size distribution of fat globules in human colostrum, breast milk, and infant formula. , 2005, Journal of dairy science.

[3]  J. Nielsen,et al.  Milk fat globule size is affected by fat production in dairy cows , 2004 .

[4]  R. Stoltz.  The thirty-fifth annual meeting of the American Dairy Science Association , 1940 .

[5]  T. W. Keenan,et al.  Origin and Secretion of Milk Lipids , 1998, Journal of Mammary Gland Biology and Neoplasia.

[6]  N. Mizuno,et al.  The important role of deep attachment in the uniform drainage of breast milk from mammary lobe , 2008, Acta paediatrica.

[7]  B. Blanc,et al.  The fat globule size distribution in human milk. , 1981, Biochimica et biophysica acta.

[8]  M. Michalski,et al.  The fatty acid composition of small and large naturally occurring milk fat globules , 2003 .

[9]  R. Kiwan,et al.  Protective function of human milk: the milk fat globule. , 1999, Seminars in perinatology.

[10]  M. Ollivier-Bousquet.  Milk lipid and protein traffic in mammary epithelial cells: joint and independent pathways. , 2002, Reproduction, nutrition, development.

[11]  C. Atwood,et al.  Collection of fore and hind milk from the sow and the changes in milk composition during suckling , 1992, Journal of Dairy Research.

[12]  F. Hytten.  Clinical and Chemical Studies in Human Lactation.—I, II, and III , 1954 .

[13]  V. Briard-Bion,et al.  Membrane phospholipids and sterols in microfiltered milk fat globules , 2007 .

[14]  S. Connor,et al.  Acute effects of dietary fatty acids on the fatty acids of human milk. , 1998, The American journal of clinical nutrition.

[15]  P. Meier,et al.  Breastfeeding in the special care nursery. Prematures and infants with medical problems. , 2001, Pediatric clinics of North America.

[16]  F. Hytten.  Clinical and chemical studies in human lactation. 1. Collection of milk samples. , 1954 .

[17]  R. G. Jensen,et al.  Lipids of bovine and human milks: a comparison. , 1990, Journal of dairy science.

[18]  T. W. Keenan.  Historical Perspective: Milk Lipid Globules and Their Surrounding Membrane: A Brief History and Perspectives for Future Research , 2001, Journal of Mammary Gland Biology and Neoplasia.

[19]  W. Whittlestone,et al.  551. Variations in the fat content of human milk during suckling , 1954, Journal of Dairy Research.

[20]  M. Murtaugh,et al.  Mothers' Milk Feedings in the Neonatal Intensive Care Unit: Accuracy of the Creamatocrit Technique , 2002, Journal of Perinatology.

[21]  L. Lethuaut,et al.  Effect of droplet size on lipid oxidation rates of oil-in-water emulsions stabilized by protein , 2002 .

[22]  W. Whittlestone.  507. Variations in the fat content of milk throughout the milking process , 1953, Journal of Dairy Research.

[23]  R. Owens,et al.  Degree of breast emptying explains changes in the fat content, but not fatty acid composition, of human milk , 1993, Experimental physiology.

[24]  J. Bitman,et al.  Lipids in milk and the first steps in their digestion. , 1985, Pediatrics.

[25]  T. W. Keenan,et al.  Intracellular origin and secretion of milk fat globules. , 2005, European journal of cell biology.

[26]  M. Michalski,et al.  Differently sized native milk fat globules separated by microfiltration: fatty acid composition of the milk fat globule membrane and triglyceride core , 2005 .

[27]  D. Sidiropoulos,et al.  Comparison of the fat content and fat globule size distribution of breast milk from mothers delivering term and preterm. , 1984, The American journal of clinical nutrition.

[28]  C. Lopez,et al.  Native fat globules of different sizes selected from raw milk: thermal and structural behavior. , 2004, Chemistry and physics of lipids.

[29]  R. G. Jensen,et al.  Lipids in human milk and infant formulas. , 1992, Annual review of nutrition.

[30]  S. Wachsmann-Hogiu,et al.  Size-dependent lipid content in human milk fat globules. , 2008, Journal of Agricultural and Food Chemistry.

[31]  M. Michalski,et al.  Oxidation products of polyunsaturated fatty acids in infant formulas compared to human milk--a preliminary study. , 2008, Molecular nutrition & food research.

[32]  P. Walstra,et al.  The milk fat globule: Emulsion science as applied to milk products and comparable foods , 1974 .