Lipid profile by direct infusion ESI-MS and fatty acid composition by GC-FID in human milk: Association with nutritional status of donors

Abstract

Nutritional status of donors of human milk (HM) to a human milk bank was investigated as a factor capable of modulating lipid concentrations of this food. Colostrum and transitional milk from 55 women with different body mass indexes (eutrophic, overweight and obese) were collected and separated into pools to evaluate the fatty acid composition and triacylglycerols lipid profile. Gas chromatograph with flame ionization detector (GC-FID) and electrospray ionization mass spectrometer (ESI-MS) were applied in these pools. Transitional milk pool from overweight donors showed the highest percentages of caprylic acid, which were 2.39 %. The trans 10, cis 12 isomer stood out in the colostrum pool of donors with overweight with values of 0.31 %. Despite the α-linolenic precursor of the omega-3 family showing higher concentrations in the colostrum pool of obese donors, long-chain polyunsaturated fatty acids (LC-PUFAs) such as eicosapentaenoic (Epa) and docosahexaenoic (Dha) showed lower values in the obese donors colostrum and transitional pools, determined by GC-FID analysis. The concentrations of Epa and Dha in the colostrum pool of eutrophic donors were 0.42 % and 0.34 %, respectively, while in the colostrum pool of obese donors the values found for Epa (0.17 %) and Dha (0.26 %) were significantly lower. In the transitional milk pool of eutrophic donors, Epa concentrations were 0.31 % and Dha 0.32 %; already in the obese donors pool, Epa and Dha presented values of 0.08 % and 0.09 %, respectively, showing a significant difference (p<0.05). The spectra of lipid profiles identified by ESI-MS revealed that the Epa and Dha are probably transferred to HM triacylglycerol from obese donors, but in intensities less than 3%. Obesity may be associated with the composition of some important LC-PUFAs, a factor that can influence the lipid quality of HM.