To investigate, researchers looked at data that had been collected on 36,000 women between the ages of 50 and 79 as part of the Women's Health Initiative trial.
Half of the women took supplements with 1,000 milligrams of calcium and 400 international units of vitamin D3 each day, while the other half took an inactive placebo supplement.
Using questionnaires and reports from doctors' visits, the researchers were able to track how many women got skin cancer over the next 7 years.
Researchers found no difference in how frequently women in either group were diagnosed with non-melanoma skin cancers or with melanoma.
However, women who reported previously having non-melanoma skin cancer, which would mean they were at higher risk for getting melanoma later, were less likely to get melanoma if they were taking the extra calcium and vitamin D.
The overall numbers were small - 10 women out of about 1,100 with a history of non-melanoma skin cancer got melanoma in the supplement group, compared to 24 out of a similarly-sized placebo group.
Cancers that develop from the pigment-producing cells of the skin are called melanoma, while cancers that develop from other skin cells are called nonmelanoma skin cancer. Melanomas are much rarer than non-melanoma cancer, and generally much more serious.
Researchers say any link between the supplement combo and skin cancer would probably be a result of vitamin D. The findings were published in the Journal of Clinical Oncology.
The link between vitamin D intake and cancer prevention is a growing area of research. Ample evidence linking vitamin D intake and a reduced risk for colorectal, breast and prostate cancers prompted the Canadian Cancer Society to increase their recommendations for the vitamin in 2007.
Currently the Canadian Cancer Society recommends that adults living in Canada should consider taking Vitamin D supplementation of 1,000 international units (IU) a day during the fall and winter. While adults at higher risk of having lower Vitamin D levels should consider taking Vitamin D supplementation of 1,000 IU/day all year round. This includes people who are older, dark skinned, don't go outside often, or who wear clothing that covers most of their skin.
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