Giving school children very high doses of vitamin D is safe - and possibly necessary - to support optimum bone growth, say researchers from the American University of Beirut.
In this new study both the short- and long-term safety of high doses of vitamin D3 were examined.
In the short-term study, 25 school children were randomly assigned to receive a placebo or 14,000 international units (IU) of vitamin D3 per week for eight weeks.
The long-term study involved 340 children who took either a placebo, 1,400 IU of vitamin D3 per week, or 14,000 IU of vitamin D3 per week. These children were followed for up to 12 months.
(Vitamin D3, as opposed to Vitamin D2, is the more potent absorbed form of vitamin D.)
No signs of vitamin D toxicity were seen in any of the children, while blood levels of the vitamin rose from 44 to 54 nanograms per milliliter (ng/mL) in the children receiving short-term supplementation.
In the long-term study, blood levels of vitamin D rose from 15 to 36 ng/mL in those taking 14,000 IU of D3 per week. Those receiving a lower long-term dose saw a smaller increase in blood levels of the "sunshine vitamin".
The body makes vitamin D3 when our skin is exposed to sunlight, however, many Canadians get too little vitamin D3 from sun exposure, especially in the winter months.
Currently, the Institute of Medicine recommends a daily vitamin D3 intake of 200 IU for children. The Canadian Cancer Society recommends 1,000 IU (international units) of the vitamin D3 daily during the fall and winter months.
One cup (250 ml) of skim milk has 100 IU of vitamin D while 3.5 ounces of canned salmon provides up to 860 IU.
More research is required to fully understand how high doses of vitamin D3 affect the health and development of children.
This study was published in the Journal of Clinical Endocrinology and Metabolism.
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