In Part I of this series on vitamin D, I outlined what this essential nutrient actually was and how it is derived in our body. In this installment I will be reviewing the extensive clinical applications and the therapeutic benefits of vitamin D. The following information comes from laboratory experiments, clinical trials, and epidemiologic surveys.
THE WINTER HEARTACHE
Statistically, deaths from cardiovascular disease are more common in the winter. These deaths in particular are more common in higher and lower latitudes. This statistic is consistent with vitamin D insufficiency. This risk is twice as high for individuals with vitamin D levels below 34 ng/dl than for those with levels above this threshold. Individuals with congestive heart failure were found to have significantly lower levels of vitamin D than controls in another study. Furthermore, vitamin D deficiency has been demonstrated as a cause of heart failure in numerous case reports.
Similarly, blood pressure also tends to run higher in the winter than in the summer. It also increases as the distance from the equator increases. Blood pressure is also affected by skim pigmentation. All of these criteria lead us to recognize a relationship between regulation of blood pressure and vitamin D levels. One study found that patients with hypertension who were given ultraviolet light treatments three times per week for six weeks had their vitamin D levels increased 162%. They also demonstrated a concurrent and significant reduction in their blood pressure. Reductions in blood pressure and heart rate were also noted in patients receiving eight weeks of treatment with just 800 IU of cholecalciferol (25-OH-vitamin D).
BLOOD SUGAR
This amazing little vitamin/hormone has also been shown to affect Type II Diabetes. Vitamin D is associated with insulin resistance, a precursor to Type II Diabetes. A research study published in the 2004 American Journal of Clinical Nutrition tested the blood sugar levels of individuals 60, 90, and 129 minutes after eating. Those who were not vitamin D deficient had much better insulin sensitivity, which means that the insulin was more effective. They also had significantly lower blood sugar levels when compared with those who were vitamin D deficient. The authors of this study noted that, when compared with metformin which made a 13% improvement in insulin sensitivity, higher vitamin D levels caused a 60% improvement in insulin sensitivity. In another study in which women with type 2 diabetes taking 1,332 IU of vitamin D per day for 30 days showed a 21% improvement in insulin sensitivity.
MUSCLES, BONES, and JOINTS
A number of years ago I had an opportunity to speak to a group of patients at a local hospital who suffered from the debilitating effects of multiple sclerosis (M.S.). In that lecture I emphasized the importance of everyone in attendance having their vitamin D levels tested. I also noted that if they were shown to be deficient that they should supplement with vitamin D to attain a sufficient level and maintain that level through routine consumption of a vitamin D supplement. Research has shown that M.S. is uncommon in sunny equatorial regions. It becomes more prevalent among those who live farther from the equator, and concurrently have significantly reduced sun exposure. In one relatively small study of 10 M.S. patients consuming 5,000 IU of vitamin D, a reduction in the number of exacerbations and an absence of adverse effects was demonstrated.
The addition of calcium AND vitamin D is recommended by not only Functional Medicine practitioners but also by conventional practitioners routinely today. The vitamin D serves the purpose of driving the calcium into the bones, and thereby strengthening them.
Osteoarthritis, which is degeneration of the joints in the body, also has been demonstrated to be affected by vitamin D levels. This is the most common form of arthritis and one that can be slowed in its progression through adequate supplementation with vitamin D. The Framingham Heart Study demonstrated that osteoarthritis of the knee progressed significantly more rapidly in individuals whose vitamin D levels were lower than 36 ng/ml. (The Framington Study is is a long-term, ongoing cardiovascular cohort study of residents of the city of Framingham, Massachusetts. The study began in 1948 with 5,209 adult subjects and is now on its fourth generation of participants.) In another study, it was demonstrated that osteoarthritis of the hip progressed more quickly in those who had vitamin D levels lower than 30 ng/ml.
COMING UP...
In my next installment of this series, I will be reviewing the relationship of vitamin D to a number of other conditions including epilepsy, depression, migraine headaches, and yes, even cancer.
