Nutrition: Keep the vitamin D coming

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It’s back to school time. Gone are the endless hours in the great outdoors. It’s also a time when vitamin D levels traditionally drop. And according
to accumulating evidence,
this vitamin D shortfall may take a
toll on our health, right through the
life cycle from infancy until old age.
But first, here’s a little background
on vitamin D, also known
as the sunshine vitamin. It’s
produced by the body when bare
skin is exposed to ultraviolet light
of sufficient intensity. For much
of the year, from September until
June, this type of sunlight is missing
in action in Canada. Pair that
with the practice of safe sunning,
especially little ones who may be
slathered from head to toe with
sunscreen that blocks vitamin D
production, shortages of this nutrient
are thought to be widespread
in Canada, even in the summer

Scientists are now investigating
vitamin D and its impact on
the rising incidence of various
auto-immune diseases, type 1
diabetes – what used to be called
juvenile-onset diabetes – and multiple
sclerosis. And low vitamin D
during childhood and adolescence
may boost the odds of developing
an auto-immune disorder even
years later.

Another area being investigated
is that of allergies and immune system
functioning. Is it a coincidence
that the extraordinary increase
in the number of peanut allergies
seems to go hand in hand with the
same time period that safe sun
practices began?

Autumn also marks the time
when seasonal illnesses are on
the rise and again, vitamin D may
play a role. Some researchers have
taken to calling some infections low
vitamin D season flu rather than
just the seasonal flu.

Japanese scientists assessed the
effect of vitamin D supplements on
the incidence of a particular seasonal
flu in school children. During
flu season, one group was given
1,200 International Units (IU) of
vitamin D per day compared to no
treatment in the other group. Not
only was there a 50 percent drop in
the number of youngsters getting
the flu in the vitamin D group, they
also had a much lower likelihood of
experiencing asthma attacks. Other
studies are showing that vitamin
D may also lower the incidence of
common ear infections.

Do the math

If you’re relying on nutrition labels
to help you ensure you’re feeding
your kids adequate amounts of vitamin
D, think again. The nutrition
facts box on food labels may lead
you astray when assessing how
much vitamin D is in a food.

That’s because the Daily Value
(DV) on labels is based on 30-yearold
information, when the recommended
daily intake was 200 IU.
So, while the nutrition information
for a cup of milk states it contains
45% DV, in reality, that 100 IUs in
a cup of milk are nowhere near
almost half a day’s intake.

But a number of glasses of milk
can add to daily totals, as can foods
like fatty fish such as salmon and
mackerel. A three-ounce serving of
cooked salmon includes just under
500 IU of vitamin D. It’s likely
we’re going to see more fortified
foods in the marketplace as well.
For example, look for a new type of
mushrooms containing vitamin D.
When the mushrooms are exposed
to ultraviolet light of a certain intensity,
they also produce vitamin
D. A 100-gram serving – less than
one half cup of chopped mushrooms
– provides a whopping 280
IU of vitamin D.

But getting to the amounts that
experts are recommending – 1,000
IU per day – can be tough with
food alone. You might want to do a
quick general assessment of your
children’s totals from food and
then use supplements for the rest.

One popular supplement – cod
liver oil – can supply a daily dose in
just one tablespoon, but be aware
that it’s also high in vitamin A,
which in larger amounts can lead
to bone thinning. Excess vitamin
A is also a concern for pregnant
women as it is associated with
birth defects.

Vitamin D daily quotas for babies and children

Recommended Daily
International units (IU),
minimum to Upper Limits

Newborn to six months:
400 to 1,000
Six months to one year:
400 to 1,500

One year to three years:
600 to 2,500

Four years to eight years:
600 to 3,000

Eight and up:
600 to 4,000

If the amounts sound
like a lot, consider that
20 to 30 minutes
outdoors with bare arms
and legs during summer
would produce about
10,000 IU on average.
Those with darker
skin would need longer
to produce that amount.

Vitamin D food sources

3 ounces cooked
sockeye salmon: 447 IU

3 ounces tuna, canned
in water, drained: 154 IU

1 cup vitamin-D
fortified milk: 100 IU

1 cup vitamin-D fortified
orange juice: 100 IU

1 tbsp vitamin-D fortified
margarine: 60 IU

1 large egg: 28 IU

1 cup vitamin D-fortified
non-dairy milk or other
beverage: 100 IU

Rosie Schwartz is a Toronto-based
consulting dietitian in private practice
and is author of The Enlightened Eater’s
Whole Foods Guide (Viking Canada).
Visit for more on healthy eating.

Originally published in ParentsCanada magazine, August 2013.

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