How much vitamin D?

Public health agencies around the world are at odds about how much vitamin D people should take daily. Heath Canada says Canadians need 200 international units (IU), while the Harvard School of Public Health is trying to get the U.S. Food and Drug Administration to raise their recommendation from 400 to 800 IU daily. The Canadian Cancer Society says 1,000 IU is enough and the Canadian Pediatric Society recommends 2,000 IU if you are pregnant and/or breastfeeding.

Sources of vitamin D are varied. It can be found in many foods, most notably in eggs, milk and some fish; it can be taken as a supplement in pill form; or the body can be spurred on to make it with exposure to UVB rays in sunshine. Twenty minutes in the sun can be equivalent to getting 20,000 IU. But depending on where you live, relying on sunshine can be problematic.

“We live in a country where we could stand naked in the sun for over seven months of the year and not be able to synthesize any vitamin D,” says Canadian-based Dr. Stanley Zlotkin, a nutritional and public health scientist at The Hospital for Sick Children in Toronto. “The angle of the sun doesn’t work for Canadians.” Especially in winter when the sun is low in the sky and people are likely covered up from the cold.

Dr. Zlotkin, a recipient of an award of excellence from the Canadian Institutes of Health Research for his work in developing nations, says vitamin D is a nutritional deficit in Canada that concerns him now. He and other researchers have confirmed that rickets, once common and now rare, is back on the rise in Canadian children.

Rickets and vitamin D supplementation

Rickets is a softening of the bones caused by a lack of vitamin D, calcium and malnutrition in general. In Canada, by law, milk is fortified with vitamin D to protect Canadians against rickets. “Milk was chosen because it’s a fluid that most people drink,” says Zlotkin. Nevertheless, according to the Canadian Medical Association Journal, rickets remains persistent in Canada. Zlotkin says there is particular concern that some communities in Canada’s far north are not drinking fortified milk, are not supplementing their infants with vitamin D, and are probably not being exposed to enough sunlight.

Canadian immigration patterns have almost certainly affected the overall rickets statistic. People from countries where exposure to sunlight is not an issue are now in a very different environment. And, darker skinned people do not absorb as much UVB rays as lighter skinned people making them even more susceptible to vitamin D deficiency.

“Vitamin D supplementation is a very safe intervention,” Dr Zlotkin says. He recommends taking 1,000 IU of vitamin D daily, especially during Canada’s fall through spring months, when the amount of sunshine hitting the ground is at its lowest.

Facts about vitamin D

• It is not a vitamin at all. Vitamin D is a hormone. Hormones are messengers that tell the body to do something. Vitamin D elevates the level of calcium in the blood by increasing absorption of calcium in the intestines, reducing urinary excretion of calcium and mobilizing calcium in the bone.
• The body makes Vitamin D through the oils that reach the surface of the skin. This oil chemically reacts with the sun and is reabsorbed by the body.
• Without enough vitamin D in the first year of their lives, babies can develop rickets.
• Vitamin D pills are made from chemically enriched, purified oils wrung out of sheep’s wool.

	VITAMIN D A vitamin that helps the body absorb and use calcium. It's produced through sunlight exposure and can be added to the diet through supplements.

	CALCIUM A mineral found in teeth, bones, and other body tissues.

	HORMONE A chemical produced in one part of the body, and released into the blood to trigger or regulate particular functions in other parts of the body. Synthetic hormones, made for use as medicines, can be the same or different from those made in the body.