title: Changes of fatty acid composition of human milk during the first month of lactation: a day-to-day approach in the first week.
abstract: BACKGROUND
  Fatty acid composition of human milk (HM) is known to change considerably during lactation. However, we were unable to find data on changes of fatty acid composition of HM during the very early phase of lactation, i.e. in the first week of life.
  
  
  METHODS
  HM samples were obtained from 18 healthy lactating women every day during the first week and thereafter on the 14th and 28th days of lactation. Fatty acid composition of colostrum and mature HM samples was determined by high-resolution capillary gas-liquid chromatography.
  
  
  RESULTS
  Values of the n-6 essential fatty acid, linoleic acid, in HM did not change significantly during the first month of lactation, whereas values of the n-3 essential fatty acid, alpha-linolenic acid, showed significant increases during the first 2 weeks of lactation (1st day: 0.49 [0.12], % weight/weight, median [ranges from the 1st to the 3rd quartile], 14th day: 0.69 [0.31], p < 0.05). In contrast, values of the n-6 long-chain metabolites, eicosadienoic-, dihomo-gamma-linolenic- and arachidonic acid, as well as the values of the n-3 long-chain metabolites, eicosatrienoic-, and eicosapentaenoic acid exhibited significant decreases during the entire period investigated. The principal n-3 long-chain metabolite, docosahexaenoic acid, showed a significant increase between the 3rd and 14th days, but a significant decrease between the 14th and 28th days (3rd day: 0.15 [0.13], 14th day: 0.28 [0.11], p < 0.05, 28th day: 0.19 [0.12], p < 0.01). There were statistically significant positive correlations between arachidonic and docosahexaenoic acid values on the 1st (r = 0.67, p < 0.01), 5th (r = 0.56, p < 0.05) and the 6th (r = 0.53, p < 0.05) days of lactation.
  
  
  CONCLUSIONS
  Fatty acid composition of HM changes significantly even during the first week of lactation. The lack of positive correlation between essential fatty acids and their long-chain metabolites suggests that it is not only the availability of essential fatty acids that influences the fatty acid composition of human colostrum.
authors.affiliation: Department of Paediatrics, University of Pécs, Pécs, Hungary.
authors.forename: Hajnalka
authors.initials: H
authors.lastname: Minda
authors.forename: Andrea
authors.initials: A
authors.lastname: Kovács
authors.forename: Simone
authors.initials: S
authors.lastname: Funke
authors.forename: Mária
authors.initials: M
authors.lastname: Szász
authors.forename: István
authors.initials: I
authors.lastname: Burus
authors.forename: Szilárd
authors.initials: S
authors.lastname: Molnár
authors.forename: Tamás
authors.initials: T
authors.lastname: Marosvölgyi
authors.forename: Tamás
authors.initials: T
authors.lastname: Decsi
mesh_terms: D000328:Adult; D002849:Chromatography, Gas; D003126:Colostrum / Q000737:chemistry*; D005227:Fatty Acids / Q000032:analysis*; D005228:Fatty Acids, Essential / Q000032:analysis*; D015525:Fatty Acids, Omega-3 / Q000032:analysis; D043371:Fatty Acids, Omega-6 / Q000032:analysis; D005260:Female; D006801:Humans; D006814:Hungary; D007774:Lactation / Q000378:metabolism*; D008895:Milk, Human / Q000737:chemistry*; D049590:Postpartum Period; D012016:Reference Values
chemical_list: D005227:Fatty Acids; D005228:Fatty Acids, Essential; D015525:Fatty Acids, Omega-3; D043371:Fatty Acids, Omega-6