Analysis Of Influence Factors Of Docosahexaenoic Acid Level In Breast Milk Of Lactating Mothers

Objective:A total of 209 healthy lactating mothers were recruited in the study, we investigated their basic information and dietary information, and detected the concentration of breast milk DHA. We also extracted the breast milk DNA and detected the five single nucleotide polymorphisms(SNPs)of ELOVL5 gene. Analyze the effect of the diet and the gene polymorphism on docosahexaenoic acid level in breast milk of lactating mothers, and provide the basis data for lactating mothers’ balanced diet and scientific feeding for the infants. Method:The participants were recruited at the postpartum care center, all participants gave informed consent according to the procedures approved by the ethics committee of Jilin University, Changchun, China. Analyses were restricted to healthy mothers of Han ethnic origin, didn’t use of PUFA-containing supplements during pregnancy and lactation, gestation age between 28 weeks and 42 weeks, infants’ birth weight between 2500 g and 4000 g. Exclusion criteria included: Subjects with communication disorders, and have hypertension, diabetes, coronary heart disease, obesity, kidney disease, and other metabolic diseases were excluded from this study. Questionnaire was used to collect the basic information of lactating mothers, the breast milk of lactating mothers was collected on one day between the 22 nd –25th day postpartum and the 3d 24 h dietary recall was used to investigate the dietary information of the lactating mothers. Single nucleotide polymorphisms(SNPs)of ELOVL5 gene were detected by Sequenom mass array system. The data of basic information, dietary information, and breast milk fatty acids were digitally input in SPSS16.0 database by designated persons. The on-line analysis software SNP stats was used, we selected the optimal genetic model according to Akaike Information Criterion(AIC), then described the concentration of breast milk DHA. Normally distributed data were expressed as mean±SD and skewed distribution data were expressed as median±IQR. Pearson and Spearman were used to analyze the correlation between influence factors and the concentration of DHA in breast milk. P< 0.05(two-tailed) was considered statistically significant. Result:1. Participants were(30.00±4.00) years old, and the average gestational age was(39.00±1.29) weeks, most of them(60.20%) have a normal body mass index(BMI) ranging from 18.5 to 23.9 kg/m2, 53.3% of them were undergraduates, 56.7% come from high household incomes(5000~10000 yuan), 31.77% had a vaginal delivery, and 68.3% had a caesarean delivery. Most(55.90%) of them were breastfed exclusively.2. It was shown in the 3d 24 h dietary recall that the intakes of vegetables, fruits and dairy intake were lower than the dietary reference intakes(DRIs), and the intakes of poultry, seafood were higher than DRIs, and the others can satisfy the DRIs. While in the intake of macronutrients, energy supply from protein and fat can be higher than the upper limit of the acceptable macronutrient distribution ranges(AMDR), while the carbohydrate supply meets the requirement of the AMDR. High quality protein from the protein intake accounted for 61.89%, meet with the 《Dietary guidelines for Women in China during pregnancy and lactation and 0~6 years old children(2007)》 that high quality protein intake higher than 30%. The intake of calcium was lower than the recommended nutrient intakes(RNI), accounted for 85.00% of the RNI. The sodium was lower than the adequate intakes(AI), accounted for 66.99% of the AI. While the iron, zinc and selenium intakes were higher than RNI. The intakes of vitamin A, vitamin C and folic acid were lower than RNI, accounted for 86.31%, 57.06% and 43.41%, respectively.3. The genotyping results showed that genotyping success rate higher than 95%. The distribution of genotypic frequencies in ELOVL5 gene was consistent with Hardy-Weinberg equilibrium(P>0.05). The result of on-line analysis software SNP stats showed the optimal model of all SNPs is the recessive model. All the factors are included in the correlation analysis: maternal age, seafood intake, lipid intake were positively correlated to the concentration of breast milk DHA(P ranges from 0.001 to 0.041), poultry, dairy products showed a weak negative correlation with the concentration of breast milk DHA(P<0.01). The result of One Way ANOVA showed carriers of major alleles of SNPs(rs2294867, rs9357760 and rs23971420) in ELOVL5 were associated with higher levels of DHA compared to minor allele carriers, and correlation analysis was statistically significant(P<0.05), And different genotypes of rs209512 and rs12207094 may be associated with DHA level(P<0.1). All the above factors included in the regression analysis, the final results showed that the dairy intake was negatively correlated to breast milk DHA level. Conclusion:1. The study populations were cereal-based diet, the intake of meat, poultry and seafood were adequate, but the constitution of diet was still unbalanced, the vegetables, fruits, milk and dairy products intake were inadequate.2. Univariate analysis showed that the breast milk DHA levels was higher in carriers of the minor allele homozygotes of ELOVL5 rs2294867, rs9357760 and rs2397142 compared with the major allele carriers(P <0.05), and we didn’t find the difference in breast milk DHA level btween the carriers of ELOVL5 rs209512 and rs12207094 minor allele homozygotes and the major allele carriers.3. The concentration of breast milk DHA of the participants in this study decreased with the increased intake of dairy products.