Vitamin D3 – The Importance
As a resident of the Pacific Northwest where there is a notable lack of sunlight, achieving appropriate physiologic vitamin D levels without nutritional supplementation is difficult. Interestingly, it is estimated that more than 70% of U.S. citizens have low vitamin D levels, and this phenomenon is more pronounced in northern latitude countries and states. There is also a greater incidence of Lyme Disease and co-infections in the northern countries, and this may not be a coincidence. Vitamin D is particularly important in immune system regulation and cell to cell signaling which seems to be disrupted in patients with Lyme Disease and co-infections.
Vitamin D is a steroid hormone similar to estrogen, progesterone, testosterone and cortisol. Hormone D cholesterol precursors found in the skin, undergo conversion into an inactive prohormone (25(OH)D3) via ultraviolet light spectrum exposure such as sunlight. Most of this prohormone is converted to the active form of vitamin D (1,25(OH)D3, calcitrol) at the cellular level, which is then used for a variety of different functions physiological functions including immune system regulation.
The immune system has at least three important pathways affecting Lyme Disease and they include: Th1, which activates pro-inflammatory cytokines leading to inflammation, Th2, the more anti-inflammatory pathway that is required to maintain homeostasis in the body, and Th17 which is associated with autoimmune disease. Vitamin D down regulates inflammatory and autoimmune pathways, and may therefore play a significant role in allowing cells and tissues to heal from bacterial or viral infections.
Additionally, vitamin D stimulates the intracellular production of the host’s own endogenously produced antibiotics known as antimicrobial peptides (AMPs), cathelicidins and defensins. These molecules are intricately involved in the maintenance of a healthy innate immune response. Their optimal function is tightly governed by appropriate vitamin D serum and cellular levels.
Vitamin D3 supplementation should be used to increase hormone D levels, and a loading dose of 50,000iu/week for 6-8 weeks may be useful in immunocompromised patients with multiple chronic infections. Effective serum levels of 1,25(OH)D3 should be above 50ng/ml and can be monitored via periodic blood tests.
Since vitamin D is a fat soluble hormone, there may be concern for toxicity. However, this is unlikely if serum levels are maintained between 50-100ng/ml. Therefore, vitamin D3 supplementation is very safe except in certain diseases like sarcoidosis and TB where excess hormone D leads to hypercalcemia (elevated serum calcium). Additionally, periodic blood testing of calcium can be helpful in targeting the appropriate vitamin D3 dose for patients with chronic infection like tick-borne disease.
All vitamins serve unique and important functions in the maintenance of proper cellular responses and organ physiology. Vitamin D is especially important for maintaining a healthy responsive immune system.