Health
Researchers have found that the composition of breast milk changes depending on the baby's sex, environmental conditions, and a number of other factors. This applies to both females and females of some mammals. Thus, scientists are confident that the composition of breast milk is not always the same.
Breast milk fat content
Specialists from Michigan State University observed 72 Kenyan women who have recently become mothers. It is worth noting that they all lived in rural areas of Kenya, where conditions are quite favorable for life.
Studies have found that breast milk in women who have given birth to sons is fatter than milk from mothers who have daughters (2.8 percent fat content versus 0.6 percent).
But this is not the case with the poor. The breast milk of women who breastfeed daughters is fatter than that of those with male infants (2.5 per cent versus 2.3 per cent).
These data were published in an American journal of physical anthropology. This study confirmed the results of previous work by specialists, which stated that the composition of milk varies depending on the sex of the baby. Previously, experts monitored young macaques, seals, and gray deer.
The new study also found that favorable environmental conditions and proper nutrition for women in Massachusetts contribute to the fact that the mammary glands produce high-fat milk energy density for a male infant.
All these studies have proved the previously existing so-called Trivers-Willard hypothesis, the essence of which is as follows: natural selection favors daughters to get more from mothers in difficult times, while sons, on the contrary, receive more in easier conditions.
This imbalance is more pronounced in so-called polygamous societies, where men have offspring with several wives. This is common in Kenyan villages, for example.
In such a society, a boy must grow up strong. He must be a leader so that he can have several wives and children. Otherwise, he may be left with nothing, and a stronger male will take the lead.
Wealthy parents who can afford to invest as much as possible in their sons should do so, as such “deposits” will eventually provide them with many grandchildren. On the other hand, parents who are unable to help their offspring should not invest much in them.
These investments are unlikely to pay off, and offspring will begin to develop at the very bottom of the socio-economic ladder. For such families, it is much more profitable to have a daughter from the point of view of “payback”.
Robert Trivers, a biologist and leading researcher at Rutgers University, says the new study is “interesting and exciting.” Katie Hinde, co-author of the so-called Trivers-Willard hypothesis, says that in addition to fat and protein levels in milk, other components also change.
She found breast milk for male babies was higher in cortisol, a hormone that regulates metabolism.
Observations show that differences in breast milk composition can affect a child's behavior, growth and development. The milk that a mother produces is only half the story. Everything else depends on how much the baby learns it. Experts have no doubts about this.
The results of such studies may be important for all medicine and pediatrics, in particular. Scientists have long been developing a formula that could be optimal for the normal development of babies of different sexes.
The composition of breast milk
Breast milk is the first food a person receives at birth. The child's immunity, as well as his overall health, will largely depend on its quality and quantity.
In terms of its composition, breast milk best meets the nutritional requirements of the infant during breastfeeding. It also regulates the growth and weight gain of a child.
The composition of breast milk is as follows:
1. Dry substances — 11.9%
2. Fat — 3.9 percent
3. Protein — 1.0 percent (including casein — 0.4 percent)
4. Lactose — 6.8 percent
5. Various minerals — 0.2 percent
The composition of breast milk during lactation changes depending on the lactation period, time of day, environmental conditions, and some external and internal factors.
And even from the beginning to the end of each feeding, milk changes its composition. The content of most microelements, for example, water-soluble vitamins (ascorbic acid, nicotinic acid, thiamine, pyridoxine) depends on the mother's diet and lifestyle.