Vitamin D is actually a prohormone, that is a substance that is converted into a hormone, a chemical messenger. When the skin is exposed to ultraviolet B radiation it forms vitamin D that is then transported to the liver and kidneys to be activated. Vitamin acts through the vitamin D receptors in the nucleus of the cell and affects the activity of genes. While many people are familiar with vitamin D for its role in the absorption of calcium in the intestines, it plays a much larger role in the body. Vitamin D is involved in cell division and is a potent modulator of the immune system, as well as other roles. Vitamin D can become deficient in people not exposed to sunlight, people with inflammatory bowel diseases and malabsorption issues, those who are obese, those taking certain medications such as Proton Pump Inhibitors for acid reflux or medicine for seizures, as well as people with magnesium deficiency. There are not many food sources of vitamin D, but it can be attained from fish such as mackerel, salmon, and sardines. In addition, mushrooms exposed to sunlight, as well as fortified foods with vitamin D.
Researchers in the journal Autoimmunity Reviews state that vitamin D plays a role in “maintaining the integrity of the intestinal barrier.” The same authors report that vitamin D influences the gut integrity, immune modulation in the gut, as well as composition of the microbiome. The authors also state that there is “strong evidence” that vitamin D signaling to the intestinal epithelial cells is of “great importance” for controlling inflammation in the gut and intestinal wall health. In addition, a 3-month study published in the United European Gastroenterology Journal found that supplementation of vitamin D (2,000 IU daily) for people with stable Crohn’s Disease had improvement in markers of leaky gut.
People with vitamin D deficiency or suboptimal levels of vitamin D is common. The Us National Academy of Medicine defines vitamin D deficiency as a 25 (OH)D level less than 30 mol/letter and insufficiency or suboptimal level at 30-50 nmol/liter. As a reference point, many labs have a vitamin D (25 OH) reference range of 30 to 100 nmol/liter. Blood testing can identify vitamin D deficiency. I generally recommend patient with low levels supplement 2000 IU to 5000 IU of vitamin D3 daily with food (since it is fat soluble).
Most of my patient supplement 5000 IU of vitamin D3 daily with meals and take it combined with K2. However, one’s blood levels will dictate the precise dose.
Dr. Mark Stengler NMD, MS, is a bestselling author in private practice in Encinitas, California, at the Stengler Center for Integrative Medicine. His newsletter, Dr. Stengler’s Health Breakthroughs, is available at www.markstengler.com and his product line at www.drstengler.com
