Last week, a new study reported that in men diagnosed with prostate cancer, the lower their vitamin D level, the worse their prognosis. As with the breast cancer study, this study implied that if men loaded up on Vitamin D, they would improve their survivability from their cancer.
This was not surprising. Hardly a week goes by without some new study showing a relationship between Vitamin D and some disease. So what's the answer? Should you raise your vitamin D levels to levels above 50 nanograms per milliliter (ng/ml) as many Vitamin D proponents claim is needed to protect yourself against cancer, osteoporosis, falls. etc.?
I say no.
The body of evidence is becoming very clear that Vitamin D is more a disease marker than disease causer. That means that your vitamin D level indicates the severity of a disease like cancer as opposed to controlling the severity.
Although vitamin D is commonly called a vitamin, it is not actually a vitamin in the strict sense, as it can be synthesized by exposure to sunlight. It can also be consumed like other vitamins through foods like wild Salmon, certain portabello mushrooms, and almond milk (to which it is added). Vitamin D is an essential nutrient, which means that your body cannot function without it. However, there is a growing consensus that as long as your Vitamin D blood level is above 20 ng/ml, you have enough.
When a doctor tests your blood and finds that your level is low, it may mean one of two things. First, you may not be naturally producing and/or consuming enough Vitamin D. Anything below 20 ng/ml should be immediately addressed by either prudently increasing sun exposure, eating more foods with Vitamin D or taking a 1,000 mg supplement. Above that level, the evidence suggests it's safe.
However, if your Vitamin D level is below 20 ng/ml, there may be a second more nefarious reason for the deficiency. You may have an illness that you are unaware of. This merits further careful evaluation by your doctor. A low level may indicate an as yet undetected cancer that requires prompt attention.
When my older brother, z"l, battled against kidney and prostate cancer, his Vitamin D level went below 10 ng/ml. I asked his doctors to try to increase it thinking that somehow that would make a difference. They did; it didn't. That's because his Vitamin D level was simply telling us how sick he was and within a few weeks he passed.
So the next time you see a headline about the association between Vitamin D and some disease, please remember that although Vitamin D is essential to healthy human functioning, your Vitamin D blood level is one of many indicators on your health dashboard. Therefore, low levels are typically neither a cause of disease (other than rickets/osteomalacia that happen at very low levels) nor make the disease more severe as so many studies would have you believe.
So have your doctor check your Vitamin D levels at least once every couple of years, but be satisfied if it stays above 20 ng/ml. Think of Vitamin D as your Dashboard Vitamin.