Diabetes Can Lead To Poor Breast Milk Synthesis
The advantages of breastfeeding to both the mother and child are well ascertained and all mothers are strongly advised by the doctors across the world, to switch to breast feeding, within an hour of the birth of the baby. It is suggested to nurse the baby till the age of 6 months. Research has shown that breast milk can provide a wholesome diet for an infant and protects the baby from the attack of various infections. Due to increased awareness, many women including those living in the poor developing countries switch to breast feeding as they know the importance of it. But how pathetic situation would it be if a mother is not able to produce enough milk for her baby? The association between maternal physiology and lactation difficulties is less understood. Factors like stress, tensions and lack of nutritious diet, have been identified as factors having a tendency to reduce the milk production. This article elaborates the role of insulin (a hormone less associated with the milk production) in milk production and how its deficiency can lead to milk insufficiency.
Physiology of Milk Production
Milk production is a complex process involving interplay of different hormones and does not start as a supply and demand process. The process of mammogenesis or the development of breasts is controlled by different hormones like estrogens, growth hormone, insulin, adrenal corticoids and prolactin. During this time the ductal system grows and branches and the amount of fats laid down in the breasts increases. Progesterone promotes the development of breast lobules and alveoli. The alveoli acquire secretory properties. Prolactin stimulates the differentiation of alveolar epithelial cells and the process of milk synthesis.
The high levels of progesterone and estrogen inhibit the milk synthesis during the initial stages of pregnancy. The process of lactogenesis (milk secretion) takes place in two different stages.
- Stage I or lactogenesis I begins during mid pregnancy in human beings and continues till 2 days after the delivery of the baby. During this stage, the glands in the breasts become well differentiated and are capable of secreting small quantities of specific milk components like casein and lactose. Just before parturition, that is, during the last few days of pregnancy, colostrum consisting of lactose and proteins is synthesized at a slower rate. The synthesis of colostrum continues for two days after the birth of the baby. However, as the progesterone levels are very high just before parturition, the milk production is turned down.
- The onset of stage II or lactogenesis II is marked by the secretion of copious milk. This stage is associated with parturition, that is, the delivery of the baby. The placenta gets delivered along with the baby, facilitating the drastic decrease in the levels of progesterone. High prolactin together with low progesterone stimulates the milk secretion at this stage. This stage is marked by the programmed transformation of the mammary epithelium which involves:
- Changes in the permeability of the paracellular pathway between epithelial cells.
- Changes in the secretion of protective substances, such as immunoglobulins, lactoferrin, and complex carbohydrates.
- Increased rate of secretion of all milk components.
Hormonal Control of Milk Secretion
The first two stages of lactogenesis are completely under hormonal control and take place irrespective of the fact that the mother is breastfeeding her baby or not.
- Prolactin secreted by the anterior pituitary plays a primary role, as it binds to the receptors in the mammary epithelial cells and stimulates synthesis of mRNA of milk proteins.
- Oxytocin secreted by the posterior pituitary is responsible for the local (autocrine) control of the milk synthesis. This lactogenesis III stage is stimulated by the suckling at the breast and milk removal controls the secretion of this hormone.
- The role of few other hormones like insulin, thyroxine, cortisol has been discovered but the exact mechanism of their action is not yet clear.
A new study conducted by scientists at Cincinnati Children's Hospital Medical Center shows that the hormone, insulin, is very important for making breast milk.
Details of the Study
This new study based on RNA sequencing (RNA-Seq) technology could give an accurate idea about the specific genes which get switched on in the human mammary gland during lactation. Scientists got the picture of the RNA of the mammary gland from the breast milk. Earlier concept was that insulin had no direct role in the regulation of milk synthesis as the milk making - cells of human breasts do not depend on insulin for the uptake of sugars. However, scientists today believe that insulin has much more to do than simple uptake of sugars.
Women with markers of sub-optimal glucose metabolism like - being over weight, being at an advanced maternal age, or having a large birth-weight baby have been correlated with longer time required for the milk synthesis. This suggests the role of insulin in the mammary gland. In fact, the sensitivity to insulin increases dramatically during the lactation period. Information obtained after RNA sequencing shows the switching on of the insulin receptor and its downstream signals during the transition of normal breasts into a biofactory which can manufacture huge quantities of proteins, fats and carbohydrates to nourish the infants. This study links insulin resistance or inefficient glucose metabolism with insufficient milk supply. The intracellular signals triggered by the binding of the insulin with the cellular receptors get suppressed by the expression of the PTPRF gene (Protein tyrosine phosphatase, receptor type, F). This gene was found to be over expressed in insulin resistant mothers, hence linking the insulin resistance with insufficient milk supply.
The rate of pre-diabetes and diabetes is increasing at an alarming rate. Modern life style habits including the lack of physical exercises, along with improper diet, are correlated with diabetes, especially type 2 diabetes. The disturbances in normal life patterns of a diabetic patient are well known, but its effect on milk synthesis is a new concept. So women planning for a baby should be double careful to control the blood sugar levels, so that the new-born can have mother’s milk which is “Ambrosia” for him/her.
My source of information
Lemay, D, D., et al. (2013). RNA Sequencing of the Human Milk Fat Layer Transcriptome Reveals Distinct Gene Expression Profiles at Three Stages of Lactation. PLoS ONE, 8 (7), e67531.