What has this study proven, and how much difference does it really make?

Let's not forget that without incident millions of mums around the world  have feed their babies expressed breastmilk that has been expressed at different times of the day, and with the advent of freezers even in different periods of their babies lives. And let's not forget life-saving breast-milk banks.

We have to discuss the comments of Cristina L. Sánchez, the lead study author and researcher at the Chrononutrition Lab at the University of Extremadura, Spain as they have become news, and are already being included on breastfeeding web-sites around the world as fact - BUT *WARNING * WARNING * HER SENSATIONAL COMMENTS CANNOT BE CONCLUDED FROM HER STUDY!

No wonder at the end of each news article there is a comment about how good breastfeeding is - one news article even saying "The World Health Organisation (WHO) says breast milk is the best food for the newborn, and should not be substituted, since it meets all the child's physiological requirements during the first six months of life." Otherwise with the types of comments being made by Sánchez, mothers might reach for the formula rather than feed their baby breastmilk expressed at the "wrong" time of day. AND THIS IS THE REAL DANGER OF THESE UNPROVEN COMMENTS.

This article in the New Scientist (1) tells us that:
     "Since previous studies have also hinted that bottle-fed infants have more problems sleeping through the night, Sánchez's colleague, Javier Cubero, has been investigating whether sleep-inducing nucleotides could be added to formula milk.
     In a separate study, Sánchez and Cubero created a "night-time" milk by adding 5'AMP and 5'UMP" (2 OF THE 3 NUCLEOTIDES IN THE STUDY) "to standard formula milk. Infants receiving this milk between 6 pm and 6 am, and normal milk during the day, fell asleep faster and spent longer sleeping than when they drank standard formula milk all the time."

So now we get to the crux of the problem. Sánchez's study into sleep inducing nucleotides in breastmilk is funded by formula companies! Her study is interesting, but the conclusions that she draws do not follow, and are pseudo-science.

What are the pseudo-science comments that Cristina L. Sánchez has made?
* "It is a mistake for the mother to express the milk at a certain time and then store it and feed it to the baby at a different time." (1,2,3)
* "You wouldn't give anyone a coffee at night, and the same is true of milk. It has day-specific ingredients that stimulate-activity in the infant, and other nighttime components that help the baby to rest." (2,3)

And other unhelpful comments that are made in the news articles as a direct result of Sánchez's comments include:-
* "Mothers who use a breast pump to express milk during the day and then bottle-feed it to their baby at night may be letting themselves in for a sleepless night." (1)
* "Cappuccino time! Breast milk expressed in the mornings should be given to babies at the same time of day so it doesn't disrupt their sleep." (2)
* "Breast-fed babies receive a different milk drink depending on the time of day - the natural equivalent of cappuccino in the morning and Horlicks at night, say scientists. Breast milk delivered in the morning gives infants a pick-me-up because it contains natural stimulants. But the night-time version will help babies sleep thanks to calming chemical compounds, a report claims. This means mums who express milk for feeding from a bottle should make sure it is given to baby at the same time it came from the breast - otherwise it could disrupt sleeping patterns. The report in the journal Nutritional Neuroscience might explain why some babies sleep or become active at odd times of day or night when working mothers express milk for use later in the day. They could be giving morning milk in the evening
and vice versa." (2)
* "The composition of breast milk changes throughout the day and it is a "mistake" for the mother to express the milk and store it for feeding the baby later, says a new study. The baby should be given milk at the time of day that it issues from the mother's breast." (3)
Let's not forget that these types of comments will result in some mums reaching for the tin of formula, rather than feeding their baby expressed breastmilk that was expressed at the "wrong" time of day.

So what was the study about, and what conclusions can be legitimately drawn from the study?

But first what did the study NOT look at? THE STUDY DID NOT LOOK AT "DAY-SPECIFIC INGREDIENTS THAT STIMULATE-ACTIVITY IN THE INFANT". Therefore Sánchez should NOT have said "It is a mistake for the mother to express the milk at a certain time and then store it and feed it to the baby at a different time. You wouldn't give anyone a coffee at night, and the same is true of milk. It has day-specific ingredients that stimulate-activity in the infant, and other nighttime components that help the baby to rest.”

What was the study about? From a MEDIA RELEASE by the Extremadura University "Scientists looked for three nucleotides in breast milk (adenosine, guanosine and uridine), which excite or relax the central nervous system, promoting restfulness and sleep, and observed how these varied throughout a 24-hour period. The milk, collected from 30 women living in Extremadura, was expressed over a 24-hour period, with six to eight daily samples. The highest nucleotide concentrations were found in the night-time samples (8 p.m. to 8 a.m.)." (3)
(THE WORD EXCITE IN THIS MEDIA RELEASE IS MISLEADING - THEY ONLY LOOKED AT THE RELAXING NUCLEOTIDES.)

"The combination between them decides whether a baby is restless or sleepy or normally active." (2) (AGAIN MISLEADING. THE STUDY LOOKED AT THE CONCENTRATIONS OF THE  NUCLEOTIDES OVER TIME, NOT AT WHETHER COMBINATIONS MADE A BABY RESTLESS OR ACTIVE, AND THE NECLEOTIDES THAT WERE BEING STUDIED WERE THOSE STRONGLY ASSOCIATED WITH SLEEP AND SEDATION - NOT ACTIVITY.)

So what did the study really look at?

"The study looked at the concentrations of 5'UMP, 5'AMP and 5''GMP – the three nucleotides most strongly associated with sleep and sedation - in the breast milk of 30 healthy mothers who had been breast-feeding for at least 3 months. Samples of milk were collected before each feed over a 24-hour period, with between six and eight samples collected per mother. They found that concentrations of 5'AMP were highest at the beginning of the night, while levels of 5'GMP and 5'UMP increased as the night wore on. These sedatives were found at much lower concentrations in milk expressed during the day. Cristina Sánchez at the University of Extremadura SUGGESTS that 5'AMP in breast milk might be fuelling the release of the sleep-promoting neurotransmitter GABA, while 5'GMP is involved in the secretion of melatonin which helps regulate the natural body clock. 5'UMP is known to promote the amount of both REM and non-REM sleep." (Published in Nutritional
Neuroscience) (1)

And what conclusions can be legitimately drawn?
* "The chemical make-up of breast milk changes across a 24-hour period."(2)
*  "Naturally occurring chemicals called nucleotides that have previously been linked to sleepiness" (remove the word "only") "reach their highest concentrations in human breastmilk that is expressed at night."(1)
* "The nucleotide concentrations during the night were at their most sleep-inducing but less so during the day."(2)

Is any of the above a problem to breast-feeding mothers?
NO, NO, NO, NO, NO
* It is NOT a mistake to feed a baby milk expressed at a different time of day.
* It is OK to feed a baby in the evening milk that was expressed in the morning.
* The evening feeding to a baby of milk expressed in the morning WILL NOT make them stay awake, and will not act like giving them a cappuccino. (And if it did don't you think that mums would have observed this type of problem before now?)
* The evening feeding to a baby of milk expressed in the morning will just have less sleep inducing nucleotides. This does not mean that the baby will not sleep. And there are other ways to get a baby to sleep apart from breastmilk.
* Baby's fall asleep at all times of the day on breastmilk, not just in the evenings. Many mums have experienced this.
* Breastfeeding mothers should have even more confidence to put their night-waking baby to the breast.

(1)
www.newscientist.com/.../...eans-a-good-sleep.html

(2)
www.dailymail.co.uk/.../...ts-natural-pick-up.html

(3)
www.thaindian.com/.../...baby-later_100255522.html