Extensive research has shown that insufficient levels of vitamin D increase the risk of developing the diseases and health problems listed above,but research has also established that adequate levels of vitamin D significantly reduce the risk of developing them in the first place. This essential vitamin may just be a lifesaver, but unfortunately, most of us simply don’t have adequate levels of this important vitamin. In fact, vitamin D insufficiency has become epidemic.

Vitamin D is unique in the nutrient world in that it is the only vitamin made in the human body from exposure to sunlight, specifically from UVB rays. Our ancestors lived naked in the sun—hunting, gathering, fishing, and farming—for several hundred thousand years, daily producing up to 20,000 IU of vitamin D as a result. Our bodies developed based on a need for high levels of vitamin D; imagine that humans are much like plants that depend on the sun for growth and health. In fact, the human body has vitamin D receptors in every tissue and cell, influencing more than 1,000 genes. In order to positively regulate gene expression, turning genes on or off as needed, it is vital for the body to have optimal levels of vitamin D.

After vitamin D has been produced in the skin or consumed, it is transported to the liver, where it is converted into its storage form, calcidiol. This form is stored throughout the body, waiting to be used.

Once vitamin D is converted into calcidiol, it has two major functions in the body. The first is to regulate calcium levels—maintaining the body’s alkaline pH balance, an equilibrium that is critical for survival, and ensuring that calcium is deposited in the bones. Its function in regulating calcium is so vital that it takes priority; vitamin D you have stored in the body (calcidiol) will be used for this purpose first. If you have low levels, then all of the vitamin D will be used up for this important function—it is only when you have a full store of vitamin D that there is enough to be used for its second function, which is to regulate gene expression. Gene expression is the process in which information from a gene is transformed into biochemicals the body needs to function and stay healthy. For example, some genes are activated to make proteins essential for fighting diseases like cancer, while others are activated to regulate blood pressure. Other genes may be turned off, such as those that promote cancer and other diseases. As mentioned, there are vitamin D receptors in every tissue and cell in the body, and the actions of these receptors regulate gene expression in these tissues and cells.

What does healthy gene expression mean for your health? Numerous studies have shown that those with low levels of vitamin D significantly increase their risk of developing certain cancers, such as colon and breast cancers, while those with optimal levels of vitamin D may slash their risk of developing certain cancers up to 50 percent.Researchers at the Harvard School of Public Health found that Caucasians who had vitamin D blood levels of 40 ng/ml and higher reduced their risk of developing multiple sclerosis by more than 60 percent compared to those who had 25 ng/ml or less (normal levels are between 50 and 80 ng/ml).Research also shows that low levels of vitamin D may be associated with hypertension, obesity, diabetes, and heart disease. Several studies have shown that supplementing with the vitamin improves muscle strength, which helps to prevent falls. A study published in The Journal of the American Medical Association indicated that 800 IU of vitamin D daily reduced the incidence of falls in people aged 65 and older by 22 percent.

In order to positively regulate gene expression, it is absolutely essential that your vitamin D tank be kept full. But that’s the problem—most of us have sub-optimal levels of this important vitamin. A study published in the American Journal of Clinical Nutrition found that as many as 60 percent of Caucasians and more than 90 percent of African-Americans had insufficient levels of vitamin D. In a study conducted in Colorado (a state that sees more than 300 days of sunshine a year) it was found that 74 percent of seniors tested had suboptimal levels of vitamin D. In another study of senior patients, the average level of vitamin D was 18 ng/ml (nanograms per milliliter) when normal is between fifty and eighty. Almost 60 percent were under 20 ng/ml. Those with the lowest D levels had the most depression and the worst performance on objective tests for dementia and cognitive function. In each of these studies insufficient levels were defined as levels below 32ng/ml of calcidiol, the storage form of D.

For many years, it was assumed that everyone received more than sufficient amounts of D from sun exposure; therefore, everyone was routinely cautioned to consume no more than 400 IUs of vitamin D daily. But when was the last time you spent significant time in the sun, without slathering on sunscreen? Sunscreen blocks UVB rays from making vitamin D in the skin. Furthermore, depending on where you live, you may not be exposed to UVB rays during certain months of the year. If you live north of about 37 degrees latitude—roughly a line from Richmond, Virginia to San Francisco—you will not be exposed to sufficient amounts of UVB light to make vitamin D from at least November through February. Latitudes between 30 and 35 degrees (including New Mexico and most of Texas) have insufficient UVB sunlight two months of the year. Additionally, the darker your skin and the older you are, the less vitamin D you will produce from sun exposure, even at those times of the year when we receive the most UVB rays.

What is an adequate level of vitamin D? To bring your levels up to the optimal 50 to 80 ng/ml, many alternative health care practitioners now routinely recommend between 2,000 and 5,000 IUs daily, in the form of vitamin D3, which is the form our bodies naturally make and is the most bioavailable. This is the amount necessary for most people to maintain a full tank of vitamin D to positively affect gene expression. A simple blood test, called the 25-hydroxy-vitamin D test, can determine if you are deficient in this important vitamin. It is difficult to improve or maintain health without first correcting a vitamin D deficiency. Vitamin D is not a miracle cure; however, it is necessary for the functioning of so many systems, organs, tissues, and genes, that improving health becomes much more difficult if you are deficient in this important nutrient.