Evening star., 1940-05-07
Of Stors. Men
And Atoms
Notebook Of Science Progress
In Field, Laboratory
And Study
By Thomas r. Henri.

Vitamin D is trapped sunshine.
In nearly every animal cell there is q
peculiar chemical structure known as q
sterol.~ Similar structures are among
the primary building stones of life. This
particular sterol is abundant in the skin.
1t becomes active when struck by
waves Of the invisible ultraviolet light in
sunshine. Then, in some way not clearly
understood, it enables the system to
absorb from the stomach the calcium and
phosphorus in the food that make teeth
and bones. It makes no essential differ
ence whether the sunshine Is trapped as
1t is needed in the skin of the growing
child or by halibut or Goldfish, which
stores it away in it's liver
A newborn child hardly can be said
to have "bones." Their place is taken by
rather stiff cartilage. This cartilage
must be filled up with calcium and phos-
phorus to become hard bone. 1t is the
D vitamin, the trapped sunshine, which
makes this possible. If there is not a
sufficient supply on hand the bones grow
weak and crooked-constituting the
widespread disease of childhood known
as rickets.
/, The anti-rickets effect of sunshine is
dependent on its ultraviolet intensity,
which varies with several factors, among
which is the altitude of the sun above
the horizon. This explains in part the
greater prevalence of ricketts, and the in
creased need of vitamin D in the diet
during the winter and early spring when
the suns altitude Is low and there are
not so many sunny days. 1t also explains
why the disease is more common in the
North than in the South.
Nature has tried, not very successfully,
to compensate. The fair-skinned races
of the North make better use of the sun
shine they receive than the dark skinned
peoples of the South. There is consid-
cradle storage of the vitamin during the
summer experiments with animals indi-
cate. A summer at the beach may sup
ply child with enough of the essential
substance to last all winter.
Rickets is still quite prevalent among
the children of the Northern States,
especially in the slum areas of the big
cities. Very little is known about the
results of vitamin D deficiency in older
children and adults. Like vitamin c, it
has been credited with preventing infec-
tions during the winter
The vitamin occurs in a relatively few
animal and fish foods. There is no con-
elusive evidence that 1t ever is found in
plants. For many years after Its dis
covery cod liver oil was the richest
known source. Now 1t is known that
several fish liver oils, such as those OF
the halibut, tuna, salmon, sardine and
swordfish, are even better. There are
small amounts in liver, cream. whole
milk and oysters. Also, some plant foods
contain a substance which can be
changed into vitamin D by ultraviolet
irradiation. either from sunlight or by
sun lamps.
A spoonful of cod liver oil contains
about 300 units of the, substance, and
the Department of Agriculture sets forth
the following requirements: Artiicially
fed babies, 300 to 800 units; breast fed
babies, 300 to 400; premature children,
600 to 800; children and adolescents, 300
to 300: pregnant women 300 to 800.
The latter must build up a reserve
supply for the expected babies. For
other adults there is no known require
ment. Probably even the average factory
or office worker gets enough sunshine
during the year to manufacture in his
own skin the minimum amounts re-
quired.
Vitamin E is the reproduction vita
min-for rats and probably for human
beings. There is no positive evidence
that man needs it at all. Without it a
female rat cannot bear living young. The
same is not true, for instance, with goats.
Extensive experiments at the Iowa State
Experiment Station show that these
animals reproduce successfully not only
with none of the vitamin in their food
but with none demonstrable in their
body tissues or milk.
The one conclusively demonstrated
function Of the vitamin in the human
being is that 1t tends to prevent abor-
ton in women. Habitual abortion is
quite rare condition. Probably enough
vitamins for all actual needs are con-
tanned in the average diet. 1t is widely
distributed in nature. The germ portion
OF wheat is an especially rich source,
while vegetable oils. green leaves and
eggs contain considerable amounts.
One other vitamin, now known to exist
In two forms, is essential to the human
being, but there is no reason to believe
that the average person does not get
enough Of it in ordinary diets. It is
vitamin K, the blood-clotting vitamin 1t
is especially essential in newborn in
fants
The richest source of this vitamin is
alfalfa. 1t occurs in most other green
leaves. Withering or yellowing of nc
leaves appears to have no effect on it.