NPR:维生素D可以预防结直肠癌吗？
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发布于: 5年前
We've known for years that vitamin D keeps bones strong. Now new research offers the most convincing evidence yet of another possible benefit to taking vitamin D, a lower risk of colorectal cancer. NPR's Patti Neighmond reports.
PATTI NEIGHMOND, BYLINE: Until now, studies looking at whether vitamin D can fight cancer have been small and inconclusive. But this study was big, analyzing research from the U.S. and around the world and adding up to more than 12,000 people. Co-author Marji McCullough, an epidemiologist with the American Cancer Society, looked at levels of vitamin D in blood samples from people who developed colorectal cancer and compared them to their healthy counterparts.
MARJI MCCULLOUGH: For both men and women, deficient levels of vitamin D were associated with a 30 percent increased risk of colorectal cancer.
NEIGHMOND: People with levels of vitamin D above what's considered sufficient for maintaining bone health had a 22 percent lower risk of colorectal cancer.
MCCULLOUGH: Vitamin D could act by reducing proliferation of cancer cells in the colon by killing those cells.
NEIGHMOND: Now, that's only a hypothesis, says McCullough. It will take lots more investigation to figure out exactly how Vitamin D might work to fight cancer. An intriguing finding of the study - women were more likely to lower their cancer risk than men. Again, it's not known why, but McCullough says it could have something to do with female hormones. The findings of the study are an important step, says Dr. Jeffrey Meyerhardt, director of the Gastrointestinal Cancer Center at Dana-Farber Cancer Institute.
JEFFREY MEYERHARDT: Really the key question is, you have some vitamin D level. Let's say you're low. Can we increase someone's level to a different level and then lower their risk?
NEIGHMOND: Right now a large study at Brigham and Women's Hospital in Boston is working to answer exactly that question - whether adding vitamin D to the diet can lower the risk of colorectal cancer. Meyerhardt expects some answers in the coming year. In the meantime, he says the best option - talk with your doctor about getting a blood test to measure vitamin D levels. It could be supplements are needed, but the best sources of the vitamin, says researcher McCullough, are food.
MCCULLOUGH: Salmon, trout, swordfish, tuna, sardines are naturally high in vitamin D.
NEIGHMOND: Then there are fortified foods.
MCCULLOUGH: Such as milk, some cereals and some orange juices.
NEIGHMOND: Other types of milk like almond milk and soy milk are also often fortified with vitamin D.
MCCULLOUGH: So you should check the label.
NEIGHMOND: A serving of salmon plus a glass of milk, she says, can fulfill currently recommended requirements for vitamin D. But McCullough says further investigation might point to increasing the recommended dose.
MCCULLOUGH: Optimal vitamin D concentrations for lowering colorectal cancer risk may be different than optimal levels for bone health.
NEIGHMOND: The findings of this study are published in the Journal of the National Cancer Institute. Patti Neighmond, NPR News.
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