Ethan A. Huff
April 16, 2010
Canadian doctors and nutritionists are urging dark-skinned immigrants coming to Canada to supplement with vitamin D in order to stay healthy. Many Canadian immigrants have relocated from countries with warmer, sunnier climates, and are exposed to far less natural sunshine in Canada than in their native lands. As a result, many of them have become deficient in vitamin D.
Immigrants come to Canada to work, to go to school, and simply to live, but few realize that the change in climate conditions could have devastating effects on their health. Darker-skinned people who come from places that receive more sunlight and are warmer for more months out of the year often have trouble maintaining healthy vitamin D levels in places like Canada that are colder and get less overall sunlight.
According to Dr. Kevin Pottie, nearly all of the immigrant and refugee patients he tests have low vitamin D levels, especially during the wintertime when the angle of the sun is at its lowest and the fewest ultraviolet-B (UVB) rays make their way to people's skin.
Reinhold Vieth, a researcher from the University of Toronto, explained in a CBC News interview that the color of a person's skin actually plays a role in how much vitamin D that person produces when exposed to sunlight.
People with lighter skin tend to produce far more vitamin D when exposed to natural sunlight than do those with darker skin. People from countries with lots of natural sunlight and warm climates generally have dark skin, a trait that Vieth believes has developed throughout their ancestries in order to protect them from sun damage. As a result, dark-skinned people must be exposed to far more sunlight than light-skinned people in order to produce the same amount of vitamin D.
"Basically, what we're doing is transplanting people from an area for which their skin is optimized in terms of its color to an area where their skin is often too dark to be healthy," he explained in an interview.
A University of Toronto study co-authored by Vieth found that those of South Asian descent are six times more likely to have vitamin D deficiency than those from European descent. Researchers believe this is due, in part, to a diet that is low in foods containing vitamin D. Many women from these cultures also wear traditional clothing that covers nearly all their skin, limiting their exposure to the sun.
Immigrants who generally spent a lot of time outside in their native lands tend to stay indoors in Canada due to the colder weather and harsh winters. As a result, they are more prone to vitamin D deficiency diseases like bone density loss, arthritis, diabetes, cancer, multiple sclerosis, and even mental illness.
The Canadian Cancer Society is recommending that people take 1,000 international units (IU) of vitamin D every day throughout the year in order to maintain good health.