Recent studies have shown a correlation between the levels of vitamin D in a person's blood and that person's risk of contracting certain cancers. Those with the highest levels of vitamin D appear to have the lowest risk of cancer.
A study conducted by Creighton University researchers involving post menopausal women also found that those who took vitamin D and calcium supplements had a significantly lower risk of cancer than women who took no supplements or only calcium. The study followed the women for a period of 4 years.
In addition to certain foods such as egg yolks and salmon, the sun provides a natural source of vitamin D. However, people with dark skin don't absorb as much vitamin D from the sun, and people living in certain northern locations, including all of Canada, don't get enough vitamin D from the sun during winter months due to its angle.
Because of the study results and Canadians' difficulty getting enough vitamin D from the sun, the Canadian Cancer Society now recommends that adults in Canada take supplements of 1000 international units (IU) of vitamin D each day in fall and winter months. The Society also recommends that people who may have lower levels of vitamin D in their blood, such as those with dark skin, older persons, and those who limit their sun exposure, should consider taking supplements year round.
Joan Lappe, the lead authority of the Creighton University study, said the Canadian Cancer Society's recommendation was "outstanding," but also said she would recommend an adult dose of 1500 to 2000 IU per day. Lappe said, "[i]t's inexpensive, its safe, and it's easy to take." However, Heather Logan, who is cancer control policy director for the Canadian Cancer Society cautions that people should not exceed 2000 IU daily from supplements and natural sources.
