Our
bodies need vitamin D to absorb calcium — the major building
block of bone. It boosts the body’s ability to absorb calcium
by up to 30-80%. Vitamin D becomes especially important as we
get older, when calcium is less efficiently absorbed. Together,
calcium and vitamin D can prevent osteoporosis — a condition
where bones become thin, brittle and break easily.
Vitamin D is often called "the sunshine vitamin,"
since our bodies can actually produce it themselves when exposed
to sunlight. In the summer, having our arms, face and hands
out in the sun for just 15 minutes a day can make a lot of vitamin
D. Unfortunately, the sun may not be the safest or most reliable
way to get enough of this vitamin. Using sunscreens to prevent
skin cancer blocks the rays needed to produce vitamin D. Dark-skinned
people absorb less sunlight than those with light skins, putting
them at risk of vitamin D deficiency. Also, many people, especially
the elderly, are at risk as they spend more time indoors. Finally,
the long, cold and dark Canadian winters mean that the skin’s
vitamin D production shuts down from early October until late
March every year.
So how can we get enough vitamin D — and just how much
do we need?
- Babies, children and adults need 400 IU (international units)
per day
- Older adults should get between 400 and 800 IU daily.
In Canada, a glass of milk (250 mL) is enriched with 100 IU
of vitamin D, making it a good source of this nutrient. Small
amounts of vitamin D are in margarine, eggs, chicken liver,
salmon, sardines, herring, mackerel, swordfish and fish liver
oil. It may be hard to get enough vitamin D from food alone,
though, so you may opt to take a supplement. Remember that most
multivitamins contain 400 IU of vitamin D, which is enough for
most people. Don’t be tempted to take higher doses —
too much vitamin D can lead to loss of calcium from bone, too
much calcium in the blood, and kidney problems.
It’s especially important that babies and children get
enough vitamin D. Kids who are short on this vitamin can get
rickets, a disease affecting bone development. Infant formulas
are already fortified with vitamin D, so bottle-fed babies don’t
need supplements. Breastfed babies, on the other hand, may need
a supplement of 400 IU per day (800 IU per day is recommended
for babies in northern communities) since breast milk is usually
low in vitamin D. Breast milk is still the perfect food for
babies but, if you’re breastfeeding, talk to your doctor
about whether your baby needs extra vitamin D.
