The fact that your immune cells possess vitamin D receptors explains why
vitamin D has been shown to influence a spectrum of illnesses blamed on specific infections. Take, for example, tuberculosis. At the turn of the last century, solaria were set up specifically for TB patients. We have always known that macrophages—germ-killing cells of the immune system—activate vitamin D. But we never understood why they did so until recently, when Dr. Robert Modlin’s and Dr. John Adams’s teams at UCLA revealed that the reason macrophages activate vitamin D is that activated vitamin D tells the macrophage to make cathelicidin, a protein that specifically kills infective agents such as TB.
Their work was published in Science in 2006, shedding light on what we had known for more than a century: sunlight can treat tuberculosis. So we now are beginning to realize why vitamin D is so important to innate immunity, especially against infectious agents we can contract in our environment. A study of postmenopausal women who took 2,000 IU of vitamin D a day showed that they had a 90 percent reduction in upper-respiratory-tract infections compared to women who took just 400 IU of vitamin D a day. This study is supported by other observations that risk of upper-respiratory-tract infection is reduced in adults who have the highest circulating blood levels of 25-vitamin D. Extending this observation to other related infections, we can surmise that vitamin D may have an impact on whether you become infected with influenza, which, as I write this, is circling the globe in a new strain called H1N1, or swine flu. Is it possible that just correcting vitamin D deficiency could decrease your risk of contracting the flu to begin with? I think it behooves all of us to be aware of our vitamin D status.
During the 1916 flu epidemic, if you were exposed to influenza, you were less likely to die if you lived in Texas than if you lived in the Northeast.
In 2009, Dr. William Grant presented a hypothesis in an article for Dermato-Endocrinology stating that low levels of vitamin D are a risk factor for sepsis, a serious blood condition usually brought on by invading bacteria. That same year, a group at the University of Pittsburgh published a study stating that vitamin D deficiency is associated with bacterial vaginosis, a highly prevalent vaginal infection that plagues many women and can lead to complications during pregnancy.
You might recall a seemingly weird connection made a few years ago between gum disease and heart attacks. On the surface, it’s an odd pairing: how can an oral infection or inflammation (periodontitis) cause a heart attack? When you connect the dots from the mouth to the cardiovascular system, you can see how this can happen. One theory is that bacteria in the mouth can affect the heart when they enter the bloodstream. From there, the bacteria can attach to fatty plaques in the heart’s blood vessels and contribute to the formation of a clot.
Once those blood clots get big enough to obstruct the flow of blood, nutrients and oxygen get restricted and the heart begins to decline in performance.
Eventually, a heart attack can occur. Another theory is that the inflammation that accompanies the periodontal disease increases the plaque buildup, which then causes arteries to swell. People with periodontal disease are almost twice as likely to suffer from coronary artery disease as those without periodontal disease.
So how does vitamin D fit in here? Because vitamin D has the power to assist the body’s natural defense against bad bacteria and inflammation, keeping healthy levels of 25-vitamin D (so that the immune cells can activate it) ultimately reduces the risk of this chain of events happening. The mechanism is the same as the one for tuberculosis: 1,25-vitamin D promotes the production of a protein (cathelicidin) that fights bacterial infections in the mouth.
Tooth decay (cavities) and periodontal disease are linked to low 25-vitamin D levels.
This also explains why dental cavities (tooth decay) have been associated with vitamin D deficiency. As most people know, dental cavities are more common among younger people (below the age of fifty) and periodontal disease is more common in older people. We were aware of a connection between sunlight exposure and the prevalence of cavities as far back as the 1930s, when an ecological study reported an inverse relationship between mean hours of sunlight and the presence of tooth decay in boys aged twelve to fourteen years living in rural or semirural regions of the United States. In other words, more sunlight exposure correlated with fewer cavities. There was a general increase in cavities, going from 2.9 cavities per boy for those living where there were more than 3,000 hours of sunshine a year to 4.9 cavities per boy for those living where
there were less than 2,200 hours of sunshine a year.
The anti-inflammatory quality of vitamin D explains why it’s been associated with the prevention and treatment of asthma and allergic reactions. It has also been touted as a great addition to steroid-based treatments for asthmatics who typically don’t respond well to traditional steroid inhalers or tablets. When vitamin D is added to a steroid regimen in these patients, the immune system responds as T cells synthesize a molecule called IL-10. This molecule, which acts as a signal, can inhibit the immune responses that cause the symptoms of allergic and asthmatic disease. Later on, when I cover a few pregnancy issues, you’ll see that vitamin D’s immunological power can play a significant role in preventing a lifetime of allergic diseases in unborn children. The power of vitamin D to support the immune system is proof again that it serves a profound function in our lives from start to finish.
I believe we’re just beginning to understand the power of vitamin D in preserving and enhancing the immune system. Just before this book went to press, more studies emerged showing that vitamin D can boost the production of proactive compounds in the skin itself and may ultimately help prevent skin infections, particularly those caused by microbial invasions. But that’s just scratching the surface, so to speak. Vitamin D, as you know by now, responds to receptors all over the body and in its deepest cells and tissues. To say vitamin D has anti-inflammatory, antimicrobial, antiviral, anti-anything properties is an understatement. Vitamin D may be one of our most reliable proactive ingredients in bolstering comprehensive immunity and reinforcing the body’s natural defenses.
In the next chapter, we’ll make a departure from the immune system but see that vitamin D serves an equally comprehensive role in aiding matters of the mind, including emotions.