Higher vitamin D levels may be linked to longer breast cancer survival, a new study reports, and the effect is particularly strong among premenopausal women.
Researchers used data on 1,666 Kaiser Permanente breast cancer patients, testing their vitamin D blood levels and following their health for seven years. The study is in JAMA Oncology.
Compared with women whose vitamin D levels are under 17 nanograms per milliliter, women with levels higher than 25 had a 28 percent higher likelihood of surviving over the course of the study, even after adjusting for many factors, including tumor stage, grade and type.
For premenopausal women, the effect was stronger. After adjusting for other variables, those with the highest vitamin D levels were 55 percent more likely to survive. Moreover, they were 42 percent more likely to survive free of invasive disease and 63 percent less likely to die of breast cancer.
“We tried hard to eliminate all possible confounding factors, but this is not a clinical trial,” said the lead author, Song Yao, an associate professor at the Roswell Park Cancer Institute in Buffalo, N.Y. “So we cannot say with 100 percent certainty that vitamin D can improve breast cancer survival.”
He advises sticking to the vitamin D recommendations of the Institute of Medicine, which calls for an intake of 600 units a day for people under 70, and 800 for people over 70.
This story originally appeared in the New York Times on November 14, 2016