Over an average of 10 years of follow-up, 276 premenopausal women and 743 postmenopausal women developed breast cancer. Calcium and vitamin D intake were moderately associated with a lower risk of breast cancer before but not after menopause. The inverse associated in premenopausal women appeared more pronounced for more aggressive breast tumors.
"A possible explanation for the evident difference by menopause status may be related to the joint relationship among calcium, vitamin D and insulinlike growth factors (IGFs)," they continue. "In vitro studies have suggested that calcium and vitamin D exert anticarcinogenic effects on breast cancer cells expressing high levels of IGF-1 and IGF binding protein 3. Calcium, vitamin D and IGF binding protein 3 have been shown in vitro to interact with each other in promoting growth inhibition in breast cancer cells." Since blood levels of these compounds decline with age, they would be more prevalent in younger, premenopausal women.
This result does not necessarily mean that vitamin D and calcium have no anti-cancer benefit as women get older. As we age we suffer decreased ability to absorb nutrients. Maybe older women do not absorb vitamin D well enough to benefit from concentrations found in food and maybe they need higher doses to achieve the same benefit as they get older.
|Share |||Randall Parker, 2007 June 02 01:12 PM Aging Diet Cancer Studies|