Vitamin D has been in the news headlines quite a bit lately, and with good reason. Although it is called “Vitamin D” because it was thought to be a vitamin and arrived after the discovery of Vitamin C, it is actually a pro-hormone. It functions much differently than a vitamin which provides a catalyst function to the metabolic working of a cell. Vitamin D receptors exist on virtually every cell in the body, and this fact alone confers it with special reverence in the biological world.
It is believed that Vitamin D is so important to the function of our cells because it was so prevalent in our bodies during our evolution. As our earliest ancestors spent much time mostly unclothed in a sun-filled environment, our tissues were bathed in massive amounts of the ‘sunshine vitamin’. As our evolution progressed, our bodies adapted to the mega doses of D and utilized the compound to facilitate many biologic processes which determine who we are today. The problem naturally arises in the modern era when we spend as much time as possible fully clothed and away from direct sun exposure. And when we do venture into the sun, we slather our skin with ultraviolet -blocking creams which prevent the creation of Vitamin D in the surface cells of our skin. As Vitamin D naturally exists in trace amounts in our food sources, and the current RDA for the vitamin is so low, our bodies become deficient. After an extended period of deficiency, our bodies eventually begin to succumb to the diseases which can be largely avoided through proper Vitamin D level maintenance.
On a very simplistic level, it is theorized that Vitamin D functions at the cellular level by providing a key to the cell’s DNA. Every time the cell replicates, it looks for the code book to determine the sequence for exact duplication of the DNA. Vitamin D, when at the proper levels, provides the key to unlock the code book so the cell can properly and efficiently complete it’s replication goal. While the cell has other mechanisms to complete the replication process, utilization of Vitamin D is the most efficient. It has been demonstrated through a number of scientific studies that low Vitamin D levels can contribute to 17 different types of cancer proliferation, as well as cardiovascular disease, stroke and even weight gain and obesity.
So how much is enough. The only true way to be sure is through blood testing using the 25 (OH)D test. It is inexpensive, and will provide a result in ng/ml. Optimal levels appear to be between 50 – 70 ng/ml. Blood saturation of Vitamin D occurs above the 50 ng/ml level, which means that all cellular targets have been filled or saturated, and likely excess is being stored in fat cells, as D is a fat soluble vitamin. Vitamin D supplementation requirements vary widely depending on a myriad of factors, most importantly body weight. That said, a good starting point for middle-aged adults is 4000 – 6000 IU/day. Supplement at that level for 90 days, and then have your blood tested. Make future adjustments with the knowledge that an additional 1000 IU of Vitamin D will typically raise the blood concentration by 10 ng/ml.