Ethnic people other than whites have insufficient levels of
vitamin D and are thus at a higher risk of debilitating diseases
such as osteoporosis, cancer and diabetes, according to a Canadian
study released Wednesday.
Researchers conducted Vitamin D tests on a group of University
of Toronto students and found that virtually all non-whites lack
vitamin D in their bodies due to their dark skins, the Canadian
press reported.
The findings reinforced the importance of skin color, which has
been known for more than a decade to be a factor determining how
easily a person is able to make vitamin D at a given latitude,
researchers say.
The research, which is awaiting publication in a medical
journal, found that 100 percent of those of African origin were
short of vitamin D, as were 93 percent of South Asians (those of
Indian or Pakistani origin), and 85 percent of East Asians (those
of Chinese, Indochinese or Filipino origin, among other
countries).
Insufficient vitamin D amounts were also found among those of
European ancestry, but were less widespread, at 34 percent of those
surveyed.
The research, based on blood tests conducted at Toronto
University's Mississauga campus in February and March, is the first
to systematically examine vitamin D levels of a group of racially
diverse, young Canadian adults and categorize the results by
ethnicity. A variety of factors influence how much of the vitamin
people have, but skin color and diet are among the most important,
researchers stress.
The results indicate that Canada may have to revise its vitamin
D intake levels and increase awareness about the risk of
deficiencies, particularly among non-whites, they say.
Some of the levels were so low that if the students had been
infants, they would have been at risk of the debilitating childhood
bone disease known as rickets, the researchers warn.
Insufficiency in the study was defined as a blood level of less
than 50 nanomoles/liter, or about half the amount found earlier
this year to prevent cancer in a US trial.
Most of a person's vitamin D is made when skin is exposed to
strong spring and summer ultraviolet light. Those with darker skins
have more pigmentation due to melanin, a natural sunscreen, that
slows the ability of skin to make the vitamin.
"The darker your skin, the lower your average vitamin D level
will be. There is no doubt about it," said Dr. Reinhold Vieth, a
professor in the department of nutritional sciences at Toronto
University and one of the researchers.
(Xinhua News Agency December 20, 2007)