The Prohormone Vitamin DThe prohormone vitamin D is comprised of a group of of fat-soluble vitamins. There are two major forms, vitamin D2 (ergocalciferol) and vitamin D3 cholecalciferol). A third synthetic form is known as vitamin D5. Of these three types, vitamin D3 is considered the natural form and is the most active. Vitamin D is important for its maintenance role of our various organ systems. The type of vitamin D we get from food or supplements is not fully active, and requires conversion by the liver and then kidneys for it to become fully active. For this reason, people with liver or kidney disorders are at a greater risk for osteoporosis. A deficiency of vitamin D may also be caused by insufficient intake along with a lack of sunlight exposure, which limits its absorption. It has a positive effect on the immune system by promoting phagocytosis, anti-tumor activity, and immunomodulatory function.
Vitamin D2 is not produced by the human body, but comes from plant and fungal sources. Vitamin D3 is derived from animal sources, and when your skin is exposed to ultraviolet rays from the sun. When this happens a cholesterol compound in the skin is transformed into a precursor of vitamin D. Researchers have learned that people with dark skin (because skin pigment blocks the sunlight) and people who live in the northern and southern regions of the hemispheres cannot produce enough vitamin D during the winter months from sunlight exposure and additional supplementation is necessary. As a prohormone, Vitamin D has no hormone activity by itself, but is converted to the active hormone 1,25-D, through a synthesis mechanism that is tightly regulated. Even when vitamin D derived from food or animal sources, ultraviolet sun rays play some part in the process. These organisms or animals are not able to synthesize the vitamin D except by the presence of ultraviolet light at some point in the synthetic chain. Most doctors who specialize in vitamin D are now recommending at least 2,000 IU per day. However, there are a number of doctors, such as Dr. J. Joseph Prendergast, an endocrinologist in Palo Alto, CA, that recommend 5,000 to 10,000. Dr. Cedric Garland of the University of California at San Diego Medical School, Moores Cancer Center, believes that 75% of breast cancer and colon cancer deaths could be prevented with adequate blood levels of vitamin D. William Faloon has a must-read editorial on the many dramatic benefits, and vast number of lives that could be saved by not being insufficient in the prohormone vitamin D.
In 2005, BBC News reported that a metastudy by scientists showed a positive correlation between consumption of the prohormone vitamin D and the prevention of cancer. Authors of the study showed through an analysis of 63 published reports that an additional 1,000 IU of vitamin D per day reduced the risk of colon cancer by 50 percent, and breast and ovarian cancer by 30 percent.
In 2007, a study showed that as many as 600,000 cases of breast cancer and colorectal cancer could be prevented worldwide each year if people had an adequate amount of vitamin D. Dr. Cedric F. Garland, a cancer prevention specialist at UC San Diego's Moores Cancer Center, estimated that 250,000 cases of colorectal and 350,000 cases of breast cancer could be prevented around the world by increasing our intake of vitamin, especially in countries further away from the equator.
The prohormone vitamin D may play a role in preventing and reversing cardiovascular disease, as well. High blood pressure and cardiovascular risk has been correlated to a deficiency in this vitamin. Under the direction of Dr. Wang, from Harvard Medical School, scientists monitored 1,739 people, with an average age of 59 years, for five years. They found the people with low levels of the prohormone vitamin D had a 62 percent increased chance of a cardiovascular event than those with normal vitamin D levels. Dr. Wang told Science Daily, "Vitamin D deficiency is associated with increased cardiovascular risk, above and beyond established cardiovascular risk factors." He also stated, "The higher risk associated with vitamin D deficiency was particularly evident among individuals with high blood pressure."
Science Daily reported on August 26, 2009, that vitamin D is a "simple, inexpensive way to radically reduce your risk of heart disease." The article went on to say that low vitamin D levels are known to nearly double the risk of cardiovascular disease in patients with diabetes. A vitamin D deficiency makes it so diabetics can't process cholesterol normally, so it accumulates in their blood vessels, which increases the risk of heart attack and stroke. New research has identified a mechanism that links low vitamin D levels to heart disease risk, which may lead to ways of fixing the problem, just by increasing your vitamin D levels. Vitamin D inhibits the uptake of cholesterol by macrophage cells. If you are deficient in the prohormone vitamin D, these macrophage cells absorb more cholesterol, and aren't able to get rid of it. These cells get clogged with cholesterol and become what are called foam cells. This is one of the earliest markers of atherosclerosis. Macrophage cells are sent out by the immune system in response to inflammation, and diabetes is often one of the diseases that activates them.
According to Dr. Joseph Mercola, a leading expert in preventive medicine, low blood levels of vitamin D have been associated with higher risk of heart disease and heart attack for a long time. He says that almost "everyone can benefit from optimizing their vitamin D levels, but if you have type 2 diabetes, it is absolutely crucial that you do so." The American Diabetes Association states that heart disease or stroke is the cause of death for over 65 percent of people with diabetes. Our bodies have 30,000 genes and vitamin D has been shown to influence approximately 3,000 of them. Almost every type of cell in our bodies have receptors that respond to vitamin D, from our brains to our bones, and researchers are continually finding additional health benefits from the prohormone vitamin D. Return to Nutritional Supplements
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