# An Insight into Probiotics Bio-Route: Translocation from the Mother's Gut to the Mammary Gland
## 5 Factors Affecting Microbial Load in the Breast Milk
### Maternal Nutrition  
Breast milk is a complex biological fluid that contains many nutrients that come from the maternal diet [1; 49]. Offspring microbiome as well as maternal immunoglobulins and macronutrients will be equally affected by the components of the breast milk [120]. The energy content of breast milk and fat concentration will be affected by the nutritional status of the mother. HBM not only contains diverse microbiota, but is also considered the greatest source of nutrients for the infants' stable growth and development [1; 49]. Breast milk proteins also show antimicrobial activities. One of the immunoglobulins known as SIgA aids in fighting the pathogenic bacteria and yeast such as _E. coli_, _V. cholerae_, and _C. albicans_, which can be found in human milk [51]. Breast-fed infants have fewer pathogenic bacteria such as _E. coli_ and _Streptococcus_, but more _Lactobacillus_ and _Bifidobacterium_ whereas formula fed infants had a higher number of enterococci and clostridia [45]. Antimicrobial components in breast milk suppress the growth of potential pathogenic bacteria and activate the progress of beneficial bacteria. Studies showed that antimicrobial compounds such as bacteriocins and hydrogen peroxide from lactic acid bacteria can suppress the growth of various pathogenic bacteria [37; 45; 51]. However, the difference in the physicochemical conditions of the intestinal environment may favor some bacterial growth and suppress the others. Probiotic, prebiotic, and symbiotic components in the body during prenatal and postnatal periods trigger changes in maternal microbiota [45]. Generally, breast milk generates an environment that aids the growth of _Lactobacillus_ and _Bifidobacterium_ and suppresses pathogenic bacteria [18]. Both bacteria play an important role in reducing the risk of spontaneous preterm delivery and in increasing the serum level erythrocyte glutathione reductase (antioxidant activity) [121]. Besides, _Lactobacillus_ GG (LGG) supplements raise the cord blood level. They also increase anti-inflammatory cytokines, IFNy, and TGFb1 in HBM. The perinatal administration of LGG reduces the clinical effects of dermatitis, itching frequency, plasma IgE levels, and elevated levels of IFN\(\gamma\) in skin biopsies. The combination of LGG and _B. lactis_ Bb12 ameliorates glucose homeostasis in healthy young females during and after pregnancy. The findings from previous studies show that probiotics supplements play a prominent role in preventing allergy development in both the mother and infant [29; 122; 123]. Prebiotics such as oligosaccharides introduced into the small intestine of a mother for digestion purposes are responsible for changing the maternal microbiota. [PERSON] et al. stated that the mass spectrometry-based tool revealed that HMOs support the competitive growth of _Bifidobacterium_ species such as _Bifidobacterium longum_ and _B. breve_[28]. The combination of prebiotics supplementation of galacto-oligosaccharide (GOS) and fruct-oligosaccharide also changed the maternal microbiota. Moreover, the increase in bacterial derived metabolites such as inulin and GOS increased the number of bacteria, which synthesize folate. Foldes are present in the large intestine for digestion and in blood stream for fetal development. Short chain fatty acids (SCFAs) are another type of metabolite produced by the prebiotics. SCFAs such as acetate, propionate, and butyrate are metabolized in epithelial cells and serve as an energy supply for the mother as well as the developing fetus. SCFAs also regulate the human gamma- to beta-globin gene switching process to produce hemoglobin [1; 124; 121]. Symbiotic treatment combines probiotics and prebiotics that help combat allergic disorders in children by altering the microbiome of the mother after delivery. They improve the response to _Haemophilus influenza_ type b (Hib) immunization, which increases antibody concentrations responding to diphtheria, tetanus, or Hib.