Day Milk vs. Night Milk
The composition of human milk has been understood in great detail only in the last few decades. And even today, scientists continue to discover new components in breast milk. It has many: a handful of proteins, a handful of fats, and hundreds of carbohydrates or sugars — most of which are not digested by the infant but serve to feed the hundreds of beneficial bacteria species in the mother’s milk that are colonizing the newborn’s gut.
Breast milk also has minerals, vitamins, hormones and enzymes; these nourish the baby and regulate thousands of metabolic processes, including digestion.
Researchers have recently learned that the levels of components in breast milk change every 24 hours to adapt to the infant’s needs; some ingredients are designed to change based on the time of day!
Take nucleotides, the basic structural unit of nucleic acids such as DNA and RNA, which encode all our genes. Some nucleotides help induce sleep in the baby by relaxing the central nervous system. A study published in 2009 in the journal Nutritional Neuroscience examined three nucleotides in breast milk — adenosine, guanosine and uridine — finding that the levels of these differed throughout a 24-hour period.
Researchers collected milk from 30 women living in Extremadura, Spain. The milk was expressed over a 24-hour period; 6 to 8 daily samples were collected. The night samples, expressed between 8 p.m. and 8 a.m., were found to contain the highest nucleotide concentrations.
Researcher Cristina Sánchez, of the Chrononutrition Laboratory at the University of Extremadura, noted that breast milk has day-specific components that stimulate activity in the baby, and night components that promote sleep in the infant.
For mothers who express milk and store it for later use, she recommended that they feed the breast milk to their infants at the same time of day that the milk was expressed. Sánchez believes that it is a mistake to express milk at a given time, then feed it to the baby at a different time.
A study from Israel, published in the European Journal of Pediatrics in 2011, found that melatonin, a natural hormone that regulates sleep-wake cycles, is released into a mother’s milk in greater quantities during the night. Researchers in that study found that exclusively breastfed infants tended to sleep better and had fewer colicky symptoms than formula-fed babies (melatonin also has a relaxing effect in the smooth muscle of the stomach and intestines). The scientists speculated that increased night-time melatonin consumption by the babies through the mothers’ night-time milk was helping the infants to relax and sleep better. Melatonin is not found in baby formulas.
Leading health authorities, including the World Health Organization and the American Academy of Pediatrics, now agree that breast milk is the most nutritious and health-promoting food for babies from birth to 6 months of age; both organizations recommend exclusive breastfeeding during the first six months. For even better results, the AAP recommends breastfeeding until one year of age, complementing breast milk with solid foods starting at six months.
While baby-formula manufacturers continue to fine-tune their products and make them better, formulas also lack the antibodies that the mother passes on to her infant in her breast milk, which help prevent stomach upset, diarrhea and ear infections in babies. These antibodies will also decrease the chances of the child developing asthma, food allergies and eczema later on.
Also missing from formulas are most sugars found in human milk, which are unique to breast milk, and which feed the beneficial bacteria in the infant’s gut. Studies have shown that the sugars, as well as the friendly-bacteria populations in the baby’s gut, both change as the baby gets older, to suit the child’s changing immune and nutritional needs. This ongoing adaptation is something that formulas cannot replicate.
Breastfeeding is now also undisputed as benefiting the mother’s health. It has been found to reduce the possibility of maternal breast cancer (especially when mothers breastfeed for a year or longer), it can help a mother lose her pregnancy weight faster, and it strengthens the psychological bond between a mother and her child.
There was a time, back in the 1950’s, when scientists and many moms believed that formula was superior to breast milk. As a result, a lot of American mothers were opting to feed their babies formula. But beginning in the 1960’s, rates of breastfeeding started increasing slowly in the United States, as they continue to do today.
While breastfeeding is relatively trouble-free for most mothers, a small percentage of moms has difficulty getting the baby to latch on properly and so forth. Experts advise new moms not to get discouraged; learning useful techniques for breastfeeding, so that you can do so successfully, will be worthwhile in many ways (not to mention cheaper!) for both your infant and you.
By Jamell Andrews