Food Structure for Nutrition - Food Colloids: Self-Assembly and Material Science - page 8

from maternal stores and to convert them into dispersed, transportable, and
bioavailable structures in milk.
Milk also provides myriad benefits to the growth, development, and health-
supporting processes of infant and mother beyond those of the essential
nutrients. The nonessential components of milk as well as those of essential
nutrients are not understood, but research is now beginning to focus on their
roles in the well-being of neonates. 23 The research strategies needed to discover
these properties are different from those used to discover the properties and
roles of essential nutrients. The latter can be studied with relative ease because
their elimination from the diet of animals leads to overt signs of deficiency in
each individual. Nonessential nutrients and their functions, however, are only
valuable within a particular context, and thus investigations of benefits of
nonessential nutrients must first recognize the context in which they are
valuable. This has become the great challenge for discovery of nutritional
value of milk's nonessential components: when and why are they beneficial?
Anything that is added to milk - literally anything - costs the mammalian
mother; so, in a highly competitive environment, if it does not profit the infant,
it would put the mother at selective disadvantage. Hence, it can be assumed
that there was a selective advantage to the incorporation of the components in
milk, and it is an exciting pursuit of modern nutrition to discover the biological
value of each.
1.6 Bioactive Molecules in Milk
Milk is an excellent source of nutrients: high-quality protein, water-soluble and
fat-soluble vitamins, calcium, phosphorus, magnesium, etc. But it is more than
this. It is also a source of proteins with biological activities that have been
demonstrated in vitro, in animal models, and in infant and adult humans. The
physiological activities provided by milk proteins in the gastrointestinal tract
include enhancement of nutrient absorption, enzyme activity, inhibition of
enzymes, growth stimulation, modulation of the immune system, and defence
against pathogens. 23,27-31
Milk provides a myriad of defensive strategies for the intestine of the infant
against exogenous pathogens, including immunological factors (antibodies, cells,
cytokines), proteins (lactoferrin, enzymes, e.g., lysozyme), oligosaccharides, and
glycoproteins, gut microflora (prebiotics), and nutrients to optimize the infant's
immune system, as reviewed in the recent literature. 32-35 Lactoferrin, lysozyme,
and haptocorrin (a vitamin B 12 -binding protein in human milk) have been
proposed 36 to influence the growth of bacteria and elimination of particular
pathogens. Although just beginning as a discrete field of nutrition, many of the
intact milk proteins contain peptide sequences that appear to be expressly
liberated by the proteases of intestinal digestion. 37
With these multiple confirmations of milk's discrete biological functions
beyond delivering simple calories, essential nutrients, and building blocks, milk
is unquestionably a knowledge resource for nutrition. Millennia of Darwinian