Although we have lots of evidence showing that vitamin D lowers the risk of many diseases, the lingering concern is that vitamin D levels might simply tell us who was healthier to begin with. In other words, healthy people go outside more often because they are healthy not the other way around.
With the passage of time and completion of the more demanding studies required to determine causation rather than association, vitamin D continues to look every bit as promising. Identifying physiologic pathways important in specific disease and influenced by vitamin D raise our confidence that the effects of D are real.
The latest such discoveries come from National Jewish Health in Denver, a famous center for asthma and allergy research. Studies they conducted of adults and children with asthma have shown that lower D levels are associated with worse asthma symptoms. Reaching further into the “how could that be” side, these studies have shown that vitamin D enhanced anti-inflammatory effects of certain immune cells and accentuated the effectiveness of steroids prescribed to treat asthma. One study found that a certain steroid was 10 times more effective when administered in conjunction with vitamin D.
Even if vitamin D only helped asthmatic patients by reducing their steroid dose, that would be great because, as the “heavy guns” of medical pharmacology, steroids have many nasty adverse effects and those effects are dose-related. However there is excellent cause to believe that D does much more and can help many asthmatics come off of medication entirely.