March 15, 2005 Globe and Mail
Almost half of new mothers and one-third of their babies suffer from vitamin D deficiency, according to new Canadian research.
Vitamin D is essential for proper bone growth and mineralization. Inadequate levels can cause rickets, and may increase the risk of osteoporosis, multiple sclerosis and some forms of cancer, including breast and colorectal cancers.
"There's a lot of vitamin D deficiency out there," said Dr. Hope Weiler, an associate professor of human nutritional sciences at the University of Manitoba in Winnipeg.
"These numbers suggest that adults are not maintaining good bone health and that children are not building bone as well as they could," she said.
The new study, published in today's edition of the Canadian Medical Association Journal, found that children with inadequate levels of vitamin D had low bone mass.
None of the children developed rickets -- a painful and once common bone-wrenching condition -- because they were all provided with vitamin D supplements, Dr. Weiler said.
"When you get to the point where you see rickets, the vitamin D deficiency is quite severe and devastating," she said.
What is unclear, Dr. Weiler said, is the health impact of long-term vitamin D deficiency and, in particular, how it may affect the growth of children and rates of osteoporosis and other diseases in adults.
A study released last year by the Canadian Paediatric Society warned that rickets is making an alarming comeback due to chronic vitamin D deficiency in Canadian children.
Vitamin D comes principally from the ultraviolet rays in sunlight and from foods such as fatty fish, for example, salmon. Some foods are also fortified with vitamin D, including cow's milk, soy and rice beverages, and margarine.
A daily intake of at least 200 international units of vitamin D is recommended as part of a healthy diet; pregnant women should get double that level, 400 IU.
But the new study, conducted among mothers giving birth at the Winnipeg Health Sciences Centre, found that 46 per cent did not attain the minimal level of 200 IU.
This occurred despite the fact that two in three moms were taking a maternal supplement that was supposed to provide adequate levels of vitamin D.
More than 70 per cent of the women who were deficient in vitamin D gave birth to a child who was also deficient.
In a commentary also published in the CMAJ, Dr. Leanne Ward, a pediatric endocrinologist at the Children's Hospital of Eastern Ontario in Ottawa, said the data underscore an "important care gap in this country: Vitamin D deficiency among Canadian mother-infant pairs is a persistent problem, despite existing recommendations for its prevention and despite ready access to vitamin D supplementation."
She said newborns who are being breastfed should receive a daily supplement of 400 IU of vitamin D, and if they live above the 55th parallel, that dose should increase to 800 IU in the winter months.
Dr. Ward said that while breast milk is undeniably the best fluid for babies, it tends not to be rich in vitamin D. Vitamin D supplements for babies are sold in liquid form, and administered with a dropper.
Vitamin D deficiency, as well as rickets, is seen principally in dark-skinned children, particularly black and aboriginal children who live in the Far North. Dark skin blocks the absorption of vitamin D from the ultraviolet rays of the sun.
The tendency to keep children out of the sun is also limiting their vitamin D.
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