Vitamin D has recently received an enormous amount of attention as the realization that many Americans are deficient in vitamin D intersects with new data regarding the possible role vitamin D may play in regulation of cancer development. A frequent question from my patients has become, “Should I be taking vitamin D?”
Last year, a group of researchers from the Mayo Clinic reported that patients with lymphoma who are vitamin D deficient had a poorer chance of surviving their disease. This was a correlative study; it did not explore whether vitamin D deficiency actually caused the patients to respond more poorly to therapy. While it is possible that vitamin D played a causative role, it is equally feasible that vitamin D deficiency was a marker for patients who were sicker for other reasons, and therefore less likely to tolerate or to respond well to treatment. Further studies will be necessary to clarify whether vitamin D deficiency caused patients to do worse, and therefore whether supplementing vitamin D in patients who are deficient will lead to better outcomes.
Until these further studies are done, what should we do? There is no indication that having higher than normal vitamin D levels will be better than having normal levels; therefore, there is not a rationale for patients with normal levels to supplement vitamin D. However, for patients who are vitamin D deficient, it seems reasonable to supplement it to normal levels, whether it will directly impact lymphoma treatment results or not. A related question is whether every patient with lymphoma should be screened for vitamin D deficiency. Until the direct impact on lymphoma outcome is clear, I cannot recommend mass screening, but discussion between patient and provider is appropriate regarding this intriguing finding.