If you've been reading my blogs, or anything else in health-related news, you've likely heard a lot of buzz about the importance of getting enough vitamin D for good health, cancer prevention, and possibly even for better cancer survival. A new study is adding to the growing consensus that getting enough vitamin D is important for all of us, but especially for those with cancer.
Health Care Providers Become Study Subjects
The research results come out of a long-running study called the Nurses' Health Study. Begun in 1976, the Nurses' Health Study has collected information on a variety of health-related factors, such as diet and exercise habits, medications, and alcohol and tobacco use from approximately 238,000 female nurses. The health of each person in this group has been tracked over time to learn more about the potential causes of conditions such as heart disease, diabetes, stroke, and cancer.
Easier Ways to Study Vitamin D
Using this study group, the researchers previously figured out a way to predict, or estimate, the level of vitamin D in each woman's body based on factors such as diet, use of dietary supplements, and sun exposure (being in sunlight helps the body make vitamin D). This is a useful research tool: It's much easier (and less expensive) to collect a questionnaire and use the information from the questionnaire to calculate an estimated vitamin D level for each person than it is to actually collect a blood sample from the entire study population and measure vitamin D levels directly.
Focusing on D and Colon Cancer Survival
For this new study, the researchers identified 1,017 women in the Nurses' Health Study who were diagnosed with colon cancer between 1986 to 2004. Next, using the method described (above) for estimating vitamin D levels in the study participants, the researchers studied the relationship between predicted vitamin D levels and survival after colon cancer. The results provide more evidence of vitamin D's importance to health and well being, even after a cancer diagnosis.
Compared with women who had the lowest predicted vitamin D levels, the women with the highest predicted vitamin D levels had 50% lower risk of dying of colon cancer after diagnosis and 38% lower risk of dying of any cause.
This study was complicated, so to summarize:
- Researchers determined a way to estimate vitamin D levels for women in the Nurses' Health Study using a questionnaire.
- The researchers then verified (using blood samples from a small number of women in the study) that these "predicted" vitamin D levels are very similar to actual levels found if a person's blood is tested for vitamin D.
- The researchers identified women who had been diagnosed with colon cancer.
- Comparing predicted vitamin D levels against records of who died after colon cancer diagnosis showed that the women with the highest predicted vitamin D levels were significantly more likely to survive after colon cancer.
This study does not prove cause and effect. It does not prove that having lower vitamin D levels caused women to have a higher risk of death after colon cancer. However, it does suggest that having adequate levels of vitamin D in the body may be one way to improve the odds of better long-term health after colon cancer diagnosis. Also on a positive note, with proper medical supervision, taking vitamin D supplements to improve vitamin D levels in your body is safe for most people.
To "D" or Not to "D"?
Before you decide that you should start taking vitamin D supplements, talk to your doctor. While vitamin D supplements generally are considered quite safe for most people, some people should not use them. Certain medical conditions or medical treatments may not mix well with high-dose vitamin D supplements.
The best ways to figure out if you should be taking a vitamin D supplement is to have your blood level tested. If you are in cancer treatment, chances are good that you are having blood tests from time to time to monitor how your body is responding to your medications. Ask your doctor to request that a vitamin D level be checked on one of your blood samples. The test isn't difficult and can give you exactly the feedback you need.
If your vitamin D levels come back low, ask your doctor to advise you on how much vitamin D to take, how long to take it, and when your blood should be rechecked to see if the supplements are working. If your vitamin D levels are normal, keep doing what you've been doing and you can be confident that you don't need a vitamin D supplement at this time.
