Human Breast Milk Is Best for Infants

Cow Milk Is for Cows: Human Breast Milk is Designed for Humans
New research provides yet another reason why human breast milk is the best for human infants

by Jerry Bergman, PhD

Since the 1970s doctors and others have come to realize the fact that human breast milk is best for human infants because it is designed for the specific health needs of humans. New research has uncovered even more solid reasons why this is true. One reason is that human breast milk contains important proteins which are either not made by the infant, or are not made in sufficient quantities. These proteins include casein, beta-casein, alpha-lactalbumin, lactoferrin, lysozyme, and serum albumin.

Furthermore, the ten essential amino acids in human breast milk closely resemble what is optimal for human infants.[1] The most common sugar in human milk is lactose, but 30 or more other oligosaccharide sugars are also found. The principal mineral constituents in human milk include sodium, potassium, calcium, magnesium, chlorine, and phosphorus.[2] Besides these essential components, every required vitamin except K are in human breast milk in nutritionally significant concentrations.[3] Vitamin K is central for blood clotting, and may cause problems in newborns, thus is not produced at maximum clotting levels until eight days after birth. For this reason, Jews circumcised males only on or after the eighth day. Lastly, human breast milk is made up of close to five percent fat, including phosphatidyl ethanolamine, phosphatidyl choline, phosphatidyl serine, phosphatidyl inositol, and sphingomyelin.

Strengthens the Immune System

It is also well-documented that human breast milk strengthens the newborn child’s immune system by several mechanisms. One important protein is critical to confer on the infant protection from pathogens, namely immunoglobulin A (IgA). IgA protects the large vulnerable outer surfaces of the gastrointestinal, respiratory, and genitourinary tracts.[4] These areas are the major sites of attack by invading pathogenetic microorganisms. IgA, as the principal antibody class in the secretions that bathe these mucosal surfaces, acts as an important first line of defense. IgA is also an important serum (blood) immunoglobulin, mediating a variety of protective functions through interaction with specific receptors and immune mediators supporting the body’s intestinal flora, the important bacteria and other microorganisms that live inside of the intestines. One reason for the protection is that intestinal microflora manufactures certain vitamins, including biotin and vitamin K.

Of note is race, age, or healthy diet variations do not significantly affect milk composition and no consistent compositional difference exists between the milk from the two breasts unless one is infected.[5]

The Role of Alarmins

The details of how the microflora and the molecular mechanisms that accomplish this phenomenon work largely have remained elusive until now. Part of the answer is proteins called alarmins which prevent intestinal colonization disorders that can lead to blood poisoning and intestinal inflammation.[6] In spite of this protection, new research has helped to answer why alarmins help to explain the effectiveness of human breast milk for health.

The Answer is the Alarmin, the “Gold” in Breast Milk

The research team headed by Dr. Dorothee Viemann at the Clinic for Pediatric Pneumology, Allergology and Neonatology at Hannover Medical School discovered how alarmins function to do their miracle work. They recently published the results of their research in the medical journal Gastroenterology. They explain the

post-natal intestinal immune system, i.e. intestinal flora and mucosa, mature through interaction with bacteria in the environment. This gives rise to optimal bacteria diversity which lasts a lifetime, affording protection against many diseases. Alarmins control this adaptation process …  these peptides and proteins both derive from breast milk and arise in the child’s intestinal tract.

They also found that to achieve full benefits of the alarmins requires normal vaginal delivery instead of C-section birth because C-section babies

exhibit lower levels of alarmins than vaginally-born infants. Additionally, premature infants are less capable of producing alarmins themselves than full-term infants. Such individuals are thus more prone to suffering from chronic inflammatory diseases.[7]

The research team measured alarmin and microorganism concentration in infant stool samples during the first year of life to better understand its effect on intestinal flora and mucosa development. They concluded,

Supplementation with these proteins could support the development of newborns which do not produce enough alarmins or get enough in breast milk. That could prevent a range of long-term conditions linked to intestinal colonization disorders, such as chronic intestinal inflammation and obesity.[8]

They also observed that that only a single dose of alarmins in mice gave them some protection against poor colonization and associated diseases.

A rewarding experience for both. (WikiCommons)

Implications of the Research for Origins

Research on human breast milk has revolutionized our understanding of infant care and health. The main problem for evolution, then and now, was the system is irreducibly complex. It will not function properly until all of the many required components are in place and functioning:

The presence and secretory capacity of the mammary gland provided the basis for the taxonomic grouping of species into the class Mammalia more than two centuries ago; and Darwin’s explanation of how lactation may have evolved satisfied an early challenge to his theory of evolution by natural selection. The challenge was that evolution of lactation was not feasible, because a neonate could not obtain a survival benefit from consuming the chance secretion of a rudimentary cutaneous gland.[9]

To respond to this challenge,

Darwin hypothesized that mammary glands evolved from cutaneous glands that were contained within the brood pouches in which some fish and other marine species keep their eggs, and provided nourishment and thus a survival advantage to eggs of ancestral species. Two hundred years after Darwin’s birth, … it is now clear that the mammary gland did not evolve from a brood pouch.[10]

The innate problems of Darwin’s conjectures forced evolutionary theorists to move on to other hypotheses. The latest evolutionary speculation postulates that the mammalian breasts evolved from some type of sweat glands. One evolutionist speculates,

Lactation appears to be an ancient reproductive trait that predates the origin of mammals…. The mammary gland apparently derives from an ancestral apocrine-like gland that was associated with hair follicles.[11]

Note the use of the word “appears” and “apparently” in this explanation because their claim is admittedly rank speculation. Reasons that it is mere speculation include the fact that

the mammary gland has no known homologue among the extant reptiles, [and thus] attempts to reconstruct its evolution must focus on evidence from living mammals. Of the numerous structures that have been hypothesized to have given rise to the mammary gland, only three remain as plausible progenitors: sebaceous glands, eccrine glands and apocrine glands.[12]

Yet another presumption is that the mammary gland evolved from the innate immune system. Professor Vorbach explains:

The purpose of the mammary gland is to provide the newborn with copious amounts of milk, a unique body fluid that has a dual role of nutrition and immunological protection. Interestingly, antimicrobial enzymes, such as xanthine oxidoreductase or lysozyme, are directly involved in the evolution of the nutritional aspect of milk. We outline that xanthine oxidoreductase evolved a dual role in the mammary gland and hence provide new evidence supporting the hypothesis that the nutritional function of the milk evolved subsequent to its protective function.[13]

The logic of this assumption is the theory that changes in the sweat composition occurred which facilitated health and survival and, thus, were selected by natural selection.[14] Therefore, the proposal is viviparity, the development of the embryo inside the body of the mother, was succeeded oviparity, producing young by means of eggs that are hatched after they have been laid by the mother. The problem is the many systems that must have evolved separately and, to be able to operate as a functional unit, secretions in an incubation patch would have been important for the regimen of eggs and hatchlings of mammalian ancestors that evolved into milk. Hormones must have first evolved, then the milk ducts and nipples, followed by the other accessory organs.[15] These structures are largely useless until they exist as a functional unit.

Summary

As research has progressed, the breast-milk feeding system has proven to be more and  more complex, increasing the contrast between other biological systems of providing nutrients to newborns. Many newborns are fed by the mother, such as is true of many birds (e.g., robins feed their brood worms), others must fend for themselves, such as newborn turtles. Aside from logical guesses, no evidence exists for the mammal milk feeding which is irreducibly complex and, therefore, explaining its evolution will continue to remain elusive.

References

[1] Jenness, R. 1979. The composition of human milk. Seminars in Perinatology 3(3):225-39, p. 225. https://europepmc.org/article/med/392766

[2] Jenness, 1979, p. 225.

[3] Jenness, 1979, p. 225.

[4] Woof, Jenny M. and Michael A. Kerr. 2006. The function of immunoglobulin A in immunity. The Journal of Pathology 208(2):270-282, January, p. 270.

[5] Jenness, 1979, p. 225.

[6] University of Bonn (Contacts: Dr. Dorothee Viemann and Dr. Thomas Ulas). 2020. The “Gold” in Breast Milk, Universitӓt Bonn, August 28. https://www.uni-bonn.de/news/192-2020

[7] University of Bonn, 2020.

[8] University of Bonn, 2020.

[9] Capuco, Anthony V. and R Michael Akers. 2009. The origin and evolution of lactation. Journal of Biology 8 Article #37, April 24. https://link.springer.com/article/10.1186/jbiol139.

[10] Capuco and Akers, 2009.

[11] Oftedal, Olav T. 2002. The Mammary Gland and Its Origin During Synapsid Evolution. Journal of Mammary Gland Biology and Neoplasia 7(3):225–252, July, p. 225.

[12] Blackburn, Daniel G. 1991. Evolutionary origins of the mammary gland. Mammal Review 21(2):81-96, June, p. 81.

[13] Vorbach, Claudia; Mario R. Capecchi, and  Josef M. Penninger. 2006. Evolution of the mammary gland from the innate immune system? BioEssays 28(6):606-616, June.

[14] Long, Charles A. 1969. The Origin and Evolution of Mammary Glands. BioScience 19(6):519–523, June, p. 519.

[15] Long, 1969, p. 519.

Dr. Jerry Bergman has taught biology, genetics, chemistry, biochemistry, anthropology, geology, and microbiology for over 40 years at several colleges and universities including Bowling Green State University, Medical College of Ohio where he was a research associate in experimental pathology, and The University of Toledo. He is a graduate of the Medical College of Ohio, Wayne State University in Detroit, the University of Toledo, and Bowling Green State University. He has over 1,300 publications in 12 languages and 40 books and monographs. His books and textbooks that include chapters that he authored are in over 1,500 college libraries in 27 countries. So far over 80,000 copies of the 40 books and monographs that he has authored or co-authored are in print. For more articles by Dr Bergman, see his Author Profile.