Everything you need to know about vitamin D

Can a deficiency really cause osteoporosis?

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vitamin D

Image, Roberto Caruso.

What it does

Vitamin D is called the “sunshine vitamin” because the body produces it when exposed to sunlight. Required for bone health, it helps the body absorb calcium and phosphate, both of which are vital for bone growth during youth and maintenance in middle and older-age, when bone mass begins to deplete.

While vitamin D hasn’t yet been proven to ward off illness, increasingly researchers are exploring whether it plays a larger role in disease prevention. “The people most fit to take vitamin D to try to improve their health would be those at risk of osteoporosis and specific cancers such as colon, prostate and breast,” say Kelly Anne Erdman, a registered dietician with the University of Calgary Sport Medicine Centre. “But there is speculation that vitamin D can help with hypertension, multiple sclerosis, as well as type 1 and type 2 diabetes.”

Are you getting enough?

Few in Canada manage to get enough sun to allow their bodies to make the necessary amount of vitamin D — even in our warmest months. “To get the sunlight exposure you need,” says Erdman, “you would have to be outside with bare arms, face and legs, without sunscreen, for at least 15 minutes on a daily basis.”

It is also tough to get enough vitamin D through diet, as it does not occur naturally in many foods. The best sources are fatty fish (including sardines and salmon), egg yolks and beef liver. Milk is fortified with vitamin D3, the animal protein-based supplement. Other non-dairy beverages such as orange juice, almond and soy milk are often supplemented with D3 or the vegan alternative, D2. But one serving usually meets just 30 to 40 per cent of the recommended dietary allowance (RDA) for adults. Health Canada has set the following guidelines:

  • infants: 400 international units (IU)
  • children and adults: 600 IU
  • 71 and older: 800 IU

Those figures are just a baseline as the daily recommended intake varies with your age, gender and other health factors, including pregnancy. Health Canada’s “safe upper limit” for vitamin D is 4,000 IU per day. Osteoporosis Canada recommends adults 19-50 get up to 1,000 IU per day and that adults over 50 take in up to 2,000 IU.

The risks

While a vitamin D deficiency can cause osteoporosis in adults and rickets in children, ingesting too much also raises serious concerns. The body stores vitamin D, and excess levels can cause harmful calcium deposits, which can lead to heart disease, kidney damage, kidney stones and more.

To figure out whether you need to supplement, and how much, Erdman recommends talking with your doctor and requesting a blood test.

More:
How to (responsibly) get vitamin D
Vitamins and minerals to optimize your health in every decade
7 silly weight-loss myths debunked by a dietitian

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