Written by Susan Sweeny Johnson, PhD, Biochem. Calcium alone appears to reduce the relative risk of cancers about 40% and with the addition of vitamin D, reduced the risk of cancer almost 80%.
The connection between UV radiation from sunlight and incidents of all cancers, not just skin cancer has been well substantiated (1-3). Recently, a lot of attention has been given to vitamin D status and it’s link to reduced cancer incidence (4-7) specifically colon and prostate cancers. In addition, increased calcium intake has been shown to decrease the risk of colon cancer (8).
In a recent study, 1180 women over age 55 were randomly and blindly given either placebo (288 women), 1400 mg calcium citrate per day(445 women), or 1500 mg calcium carbonate per day (446 women) plus vitamin D3 (1000 IU per day). They were observed for incidence of breast, colon, and other non-skin cancers over a four-year followup period. The blood concentrations of 25-hydroxyvitamin D, the form vitamin D takes in the body, increased almost 50% with supplementation but remained unchanged in the other groups.
During the first four years 20 women in the placebo group, 17 in the calcium only group, and 13 in the calcium plus vitamin D group were diagnosed with cancer. When the cancers observed during the first year were ignored as possibly originating before the onset of the study, 18 cancers occurred in the placebo group, 15 in the calcium group and only 8 in the calcium plus vitamin D group. Thus calcium alone appears to reduce the relative risk of cancers about 40%, but the risk does not decrease further when the first year cancers are not considered. This may be due to the specific elimination of colon cancers, since two colon cancers appeared in the placebo group, but none appeared in the calcium only group. The addition of vitamin D, however, reduced the relative risk of cancer incidence almost 80%, especially when the first year cancers were eliminated.
Although this study was statistically small, it does support the prevalent theory that vitamin D status is important in reducing cancer risk. Not only does the blood form of vitamin D increase calcium absorption, but at higher concentrations it exerts cell regulatory and immune effects. The current recommended intake of vitamin D is 200 to 600 IU per day. This study indicates that 1000 IU per day may be more appropriate to improve immune status.
Source: Lappe, Joan M., et al. “Vitamin D and calcium supplementation reduces cancer risk: results of a randomized trial.” The American journal of clinical nutrition 85.6 (2007): 1586-1591.
© 2007 American Society for Nutrition
Posted July 1, 2008.
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