Activated by sunlight and present in some foods and supplements, vitamin D has been associated with healthy bones and reducing the risk of diabetes and cancer.
But a new study says that the recommended dose of vitamin D needed to reap these health benefits remains unclear. To help shed some light on the topic, we talked to Dana-Farber’s Kimmie Ng, MD, MPH, who has been studying the connection between cancer and vitamin D use, as well as other lifestyle factors.
What is the connection between cancer and vitamin D?
There is a large amount of scientific and observational data that links higher blood levels of vitamin D with a decreased risk of developing cancer, including colorectal cancer and breast cancer. It has also been found to improve cancer survival.
How do I know if I’m getting enough vitamin D?
Physicians can use a blood test, called a 25-hydroxy vitamin D test, to measure how much of the nutrient is in the body. While many consider a vitamin D level of around 30 ng/ml or higher sufficient, we’ve found that the protective effects come from 35-40 ng/ml.
What is the recommended vitamin D dose for an adult?
The Institute of Medicine recommends between 600 – 800 IU. We don’t know what the optimal doses of vitamin D are for cancer prevention and treatment, although we suspect that they’re much higher than this recommendation. It is important to ask your doctor about how much vitamin D is best for you.
Is it better to get vitamin D from a pill or other sources?
Supplements are the best way to take vitamin D. Diet accounts for only 20 percent of vitamin D. A glass of fortified milk, for example, only contains 100 IU of vitamin D and isn’t enough to raise your blood levels. And while spending 10 minutes in the sun without sunblock provides 20,000 IU of vitamin D, there are other health risks to consider, like skin cancer.
Learn more about cancer and vitamin D deficiency.
Are there any vitamin D and cancer clinical trials?
We hope to begin enrolling metastatic colorectal cancer patients in early 2012 for a clinical trial evaluating the effectiveness of high doses of vitamin D in combination with chemotherapy. We will be comparing the differences between a standard dose of 400 IU of vitamin D3 with chemotherapy, versus a higher dose of 8,000 IU of vitamin D3 for two weeks, followed by a maintenance dose of 4,000 IU vitamin D3 with chemotherapy.