The Nursing Mother


Anyone who reflects upon the relation of the
mother to her young during the suckling period,
must marvel at the fact that during early life the
young mammal cannot thrive on the diet of the
adult. It must have milk for a shorter or longer
period after birth. This the lactating animal is able
to form from her food through the agency of the
mammaiy gland. The period of dependency varies
greatly in different species. Among mammals,
with which the author is familiar, the young guinea
pig is born in the most highly developed state. The
newborn cavy is capable of eating grass or succulent
vegetables during the first or second day of post-
natal life. The young rat may be safely weaned at
the age of twenty-five days, provided a highly satis-
factory diet of the type which sufficies for the adult
is then supplied. The young pig (swine) becomes
able to eat fairly liberally of the normal adult diet
at the age of six or eight weeks, whereas the human
infant must live largely on a milk diet during the
first year of life and should have a liberal allowance
of milk and of eggs during the entire growing period.


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Even eggs will not entirely replace milk during any
part of this period. It is of great importance that
we should understand the relationship between the
character of the diet of the lactating female, and the
quality of the milk which she is able to produce.
Our knowledge of this subject is still very incomplete,
but experimental studies on animals have recently
thrown light on certain very important phases of
this problem.

In order to gain information on the relation be-
tween the character of the diet of the mother and
the value of the milk which she produces, McCollum
and Simmonds l carried out a series of experiments
on lactating rats, whose diets were faulty in known
ways, and observed the effect on the growth of the
young which these mothers nursed. The mothers
were fed a highly satisfactory diet until they had
completed their term of pregnancy. As soon as the
young were born, the litter was in all cases reduced
to four, in order that the nutritive undertaking of
the mother should in no case be burdensome. The
mother was at once restricted to a diet which would
not induce any growth whatever in a young rat after
separation from the mother at weaning time. The
diets of the mothers in the various experiments were
faulty in respect to each of the factors which are
necessary for the formation of a satisfactory diet,
but the number of characters in which a single diet
was faulty varied from one to three.

In one case the mother was fed upon a diet of


purified protein, carbohydrate (dextrinized starch),
a suitably constituted inorganic salt mixture, and
an alcoholic extract of wheat germ to furnish the
unidentified dietary essential, water-soluble B. This
diet contained everything necessary for the nutrition
of a young rat during growth, except the fat-soluble
A. The problem was to find whether the mother
could, through the agency of the mammary gland,
form the missing substance, fat-soluble A. Expe-
rience has shown that the young animal after the
weaning age, cannot produce it de novo, for its own
preservation from any of the other constituents of
its food. The results of the experiment indicated
that the quantity of the fat-soluble A in the milk
produced from such a diet is below the amount
necessary for the promotion of the maximum rate
of growth in the young. It has been shown by
Osborne and Mendel, 2 that the body fats of beef
cattle contain a small amount of the fat-soluble A.
It seems certain that the body fats of an animal
which has been fed for some time on a diet rich in
this substance, will serve as a reserve supply of this
dietary essential, which the mother can secrete into
the milk. In other experiments, Chart 15, definite
evidence is presented that this substance is not
abundant in the milk unless it is present in the diet
of the mother. The presence of some fat-soluble A
in the tissues of the mother makes it especially diffi-
cult to obtain milk which is entirely free from this


Through similar experiments with diets which
contained the fat-soluble A, but not the water-
soluble B, evidence was secured that for a time the
mother is able to secure this dietary factor from her
reserve supply, but none of the growth curves in-
dicated that the substance is present in the milk
in adequate amount when the diet of the mother
lacks it. It seems certain that neither of these
substances is present in abundance in the milk of
the mother, unless it is furnished in her food.

Evidence confirmatory of this view is found in
the studies of Andrews 3 on infantile beri-beri. It
is well known that the faulty diet of rice and fish,
which furnishes the principal food of many of the
poorer classes of the Orient, does not prevent the
onset of beri-beri, and infants who nurse mothers
who are suffering from the disease, likewise develop
beri-beri. Andrews induced several Filipino women
whose infants had just died of beri-beri, to nurse
young pups, and noted that in all cases the lat-
ter failed to grow, became edematous, and lost
the use of their hind legs. Paralysis of the posterior
extremities is one of the symptoms of the disease in
man. It is evident that in the milk of these mothers
there was a shortage of the water-soluble B, for it
is a shortage of this substance which causes the
development of this syndrome.

It has been pointed out that young animals do
not grow when confined to a single seed or mixture of
seeds of plants, for the reason that these are all


lacking in sufficient amounts of the inorganic el-
ements, calcium, sodium and chlorine, and are too
poor in the fat-soluble A to support normal nutrition.
The quality of their proteins is likewise too poor
to make them very satisfactory for the support of
growth. McCollum and Simmonds have studied
the extent to which the mother is able to produce
milk of satisfactory character for the promotion of
growth in the young, when confined to a single seed as
the sole source of nutriment. Charts 15 and 16 show
the effects of such diets on the growth of the young.
The curves of rat 211 and of her litter of four
young (Chart 15) illustrate the remarkable growth
which a mother rat is able to induce in her young
when her diet is highly satisfactory, and while
doing so, she is able to increase her own weight very
appreciably. In marked contrast to this "normal"
accomplishment stands the failure of rat 738 to in-
duce more than one-third the normal rate of growth
in her young when restricted to rolled oats as her
sole food supply. The drop in the curve of the
young at the 40th day was the result of the death
of the young at brief intervals. The mother lost
weight regularly, showing that she was sacrificing
her own tissues for the preservation of her young.
Rolled oats, like the other seeds, require improve-
ment in respect to three dietary factors before it
becomes a complete food, and on such a faulty diet
the mother produces milk which is not satisfactory
for the promotion of growth in her offspring.


Rat 843, whose diet consisted of rolled oats sup-
plemented with fat-soluble A (as butter fat) induced
growth in her young at a somewhat greater rate than
she could have done, had she eaten oats alone, and
was able to keep them alive for a longer period.
The first one died on the 57th day and the others
followed in rapid succession. This mother lost con-
siderable weight up to the time that the young began
to eat of the oat and butter fat diet. Young rats,
after removal from the mother, cannot grow at all
on this diet.

Rat 899, was fed a diet of rolled oats to which was
added such an inorganic salt mixture as made good
the mineral deficiencies of the oat kernel. Her diet
was still deficient in fat-soluble A, and to some extent
in the quality of its proteins. With this food her
milk was of distinctly better quality than that which
can be produced on a diet of oats alone, or on oats
supplemented with fat-soluble A, or on oats supple-
mented with purified protein (rat 948) . From these
results it is apparent that the first limiting factor
of the oat kernel for milk production in the lactating
animal is the same as in the young for growth, viz.,
the inorganic content of the food supply.

The importance of having the inorganic content
of the diet properly constituted is shown especially
well in the performance of the mothers 983 and
1978. The former was fed rolled oats supplemented
with both fat-soluble A, in the form of butter fat,
and purified protein in the form of casein of milk.


Even with these two additions she was able to induce
less than half normal growth in her young and they
began to die at the age of 45 days, and all succumbed
in rapid succession. Rat 1978, on the other hand,
whose diet consisted of rolled oats supplemented
with a suitable salt mixture and butter fat, was able
to induce growth in her young at about two-thirds
the normal rate. The improvement of the milk
by the inclusion of fat-soluble A in the diet is very
apparent, since the young did not die during the
period of sixty days covered by the experiment, and
supports the view that this substance cannot be
synthesized by the mother.

Rat 1019, whose diet consisted of rolled oats
supplemented with purified protein and a suitable
salt mixture, shows that the mother is able to induce
nearly the optimum rate of growth in her young dur-
ing a period of thirty days, although her diet was very
poor in the factor fat-soluble A. It should be borne
in mind that the seeds, because they contain a small
proportion of cellular structures in addition to their
reserve food package in the endosperm, contain a
small but inadequate amount of the fat-soluble A.
The mother is able, when the diet of oats is corrected
with respect to two factors, protein and salts, to
concentrate in the milk the small content of the fat-
soluble A which her diet supplies. She is probably
also able to draw in some degree upon her small
store of this substance which is deposited in her body
fats, and supply the young with enough of it to


enable them to reach a state of relative independence,
which in a wild state would enable them to go in
search of food for themselves. There is abundant
experimental proof that when the protein and in-
organic content of the food are of highly satisfactory
character, animals can subsist for a long period on a
supply of fat-soluble A too small to prevent the onset
of xerophthalmia in diets of lower biological value.

These records of nursing mothers and their young
make it apparent that the former is limited in a
general way in the utilization of food for milk pro-
duction, in the same manner as in the growing young
in the utilization of food for the construction of new
body tissues. She is, however, a factor of safety for
her young in no small degree. It should be remem-
bered that a young rat cannot grow at all when,
after the weaning age, it is limited to the oat kernel,
or to the oat kernel supplemented with either salts,
protein or fat-soluble A alone, or on a diet of oats
supplemented with both protein and fat-soluble A.
In order that it may grow even very slowly it is
essential that both a suitable salt mixture and fat-
soluble A shall be added to the oat kernel. It can-
not grow normally unless the protein factor is like-
wise improved. In the records of the mothers and
young shown in Chart 15, the young continued to
grow in certain instances after the twenty-fifth day,
the age at which they may be safely weaned when
their milk supply has been of normal composition.
This fact is conclusive evidence that even after the


young become able to eat of the diet on which the
mother had produced the milk on which they were
able to grow — a diet on which they would be unable
to grow at all without some corrections and improve-
ments — they were still receiving a supplementary
milk supply from the mother. This served to correct
in some measure the faulty diet of oats plus an in-
complete supplementary addition. It seems certain
that milk production must have been very con-
siderable in amount, to thus enhance the diet of
four young whose weight collectively was about half
that of the mother herself.

The inorganic content of all the seeds is the first
limiting factor in preventing growth in young ani-
mals, and in determining the quality of the milk which
can be produced from them. The young animal
cannot grow at all on seeds unless one of the factors
corrected includes certain salt additions, yet the
mother is able to produce milk without any such
additions, which is capable of inducing a limited
amount of growth in the young. It is apparent that
one of her most important relations to her'helpless
offspring is her capacity to supply it with a better
inorganic food supply than she herself secures in her
food, when the latter is of poor quality.

The growth curves of the young of mothers whose
diets consisted of the oat kernel without and with
purified food additions, illustrate likewise very well
the results which are observed when similar ex-
periments are conducted with the wheat or maize


kernel. They emphasize the fact that for milk pro-
duction as for growth, the seeds of plants may be re-
garded as closely similar in their dietary properties.
It is therefore, rendered highly probable that the
same analogy runs through the series of food-stuffs
in their value for the production of milk of normal
character. We are not to expect, therefore, that a
diet consisting of even a complex mixture of seeds,
tubers and roots, will produce milk of highly satis-
factory character, and without undue strain on the
mother. It has been emphasized that even this list
of foods of the class whose functions are those of stor-
age organs, do not suffice even when combined with
meat, to induce satisfactory growth in the young.
It follows as a logical conclusion, that a lactating
mother will not be able to produce milk of a very sat-
isfactory character when she is restricted to such
food-stuffs. It should be reiterated that there are
two classes of food-stuffs which are so constituted as
to correct the deficiencies of seeds, tubers, roots and
meat. These are milk and the leaves of plants and
they should be used very liberally in the diet. Eggs
are in some degree to be regarded as comparable to
these, but eggs have not the favorable mineral con-
tent of the leaves and of milk, and this is one of the
most important factors in which the storage organs
of plants need supplementing.

The question will arise in the minds of many, as
to whether the inability of the young to grow on the
milk produced by mothers which were living upon


an inadequate diet, was not the result of the failure
of the mothers to produce enough milk rather than
milk of abnormal composition. It has not been
found possible to secure complete information as to
the actual amount of milk which these rats secreted,
but we have analogous data from domestic animals,
which support the view that milk secretion remains
fairly constant in the lactating animal even under
very unfavorable conditions of nutrition.

Babcock 4 has described experiments in which he
deprived cows of common salt during lactation,
other than that which they secured in their regular
ration, which was of a type suitable for the dairy
cow. The keen appetite of the herbivora for salt is
a matter of common knowledge. Deer which are
very shy. will risk any danger to secure salt at their
accustomed licks or from salt springs. The periods
of salt deprivation varied from two to fifteen months,
and some of the animals actually died, and others
were saved from death -by the administration of salt.
In no instance was there a notable decrease in the
yield of milk by these cows up to a short time be-
fore they began to fail rapidly. Indeed the fat con-
tent of the milk of the cows receiving an inadequate
salt supply was slightly higher than in the milk of
the control group.

Eccles and Palmer 5 have conducted a very thor-
ough experimental study of the influence of under-
feeding of cows on milk production, and have studied
its composition in cows whose rations were of suitable


composition, but inadequate in amount. These
results show that cows were able, during the early
part of the lactation period, to maintain the milk
flow undiminished for forty days, when receiving
but 75 per cent enough food to meet her require-
ments. Under such conditions of nutrition there
was no pronounced change in the composition of the
milk. During the latter part of the lactation period
there was some falling off in milk production as the
result of under-feeding.

Ducaisne 6 in 1870, noted that during the siege of
Paris, young and vigorous women were able to pro-
duce enough milk to maintain their infants, and in
some cases to increase their weight when they were
partially fasting. These observations, as well as
those of Andrews on women whose infants had died
of beri-beri, 3 all support the view that under con-
ditions of faulty nutrition, it is the quality of the
milk rather than the quantity which early suffers
impairment. Dr. Manuel Roxas, of the College of
Agriculture of the Philippine Islands, has informed
the author in a private communication, that the in-
fants' death rate among the natives is much higher
in the breast-fed than among the bottle-fed children.

The occurrence of infantile beri-beri, rather than
of death from starvation, further serves to demon-
strate that it is milk of poor quality, rather than
lack of sufficient amount of milk which is responsible
for the high infant mortality in those parts of the
world where the poorer classes live too largely on


food-stuffs derived from products whose biological
functions are those of storage organs, and meat.

The statement which one sees reiterated so fre-
quently, that breast feeding of infants is superior to
the best system of artificial feeding, neecfe to be
qualified to some extent. There are, without ques-
tion, in many parts of the world, large groups of
people whose diets are of such a character that the
quality of the milk produced by the lactating mother
is not such as to make it a satisfactory food for their
infants. It should be thoroughly appreciated that
the human mother should have in her diet a liberal
amount of milk in order to safeguard the health and
well-being of her infant, and of leafy vegetables,
which serve the two-fold function of a protective
food and of greatly aiding intestinal elimination.
That some mothers can induce a fair amount of


growth in their infants while taking a faulty diet,
cannot be denied, but that both mother and child
suffer impairment as the result is beyond question.
It is not enough that the diet shall furnish enough
calories and enough protein, and shall afford variety
and palatability. The peculiar dietary properties
of the food-stuffs which enter into the diet are of
paramount importance, and must be taken into con-

Attention should again be directed to the observa-
tions of Hess 7 that the diet of the negro women of
the Columbus Hill district in New York, whose diets
are derived almost exclusively from seed products,


tubers and meats, fail to nourish their infants satis-
factorily as shown by the almost universal prevalence
of rickets among the latter. It is difficult for man
to correct the dietary deficiencies of these products
by the use of the leaves of plants as his sole protective
food, because of the limited capacity of his digestive
tract. Milk in liberal amounts should always be
included in the diet of the lactating mother.

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