Vitamin D – Beyond Bone Density

It is widely understood that Vitamin D is necessary for healthy bone density.  Focus on this one benefit leads many people to mistakenly view Vitamin D as being only important for aging women in their effort to avoid osteoporosis and the dreaded “Dowager hump”.  Actually, we now understand that Vitamin D is critical to the function of virtually every cell and tissue of the body.  Regardless of age, optimal Vitamin D status can contribute to the prevention of a wide variety of ailments and chronic disease; however, as we’ll discuss, most Americans have dangerously insufficient levels of Vitamin D.  First, let’s consider just a few of the lesser known functions of this essential nutrient.

Vitamin D boosts the immune system and helps fight all kinds of infection.  Research suggests that Vitamin D performs this function by contributing to the regulation of genes which guide the immune system to attack and kill germs like bacteria and virus.  So, even for such as the ubiquitous common cold or even flu, proper Vitamin D levels (and supplementation) can be helpful in treatment and prevention.

Weight loss efforts may also be more effective with Vitamin D supplementation.  A recent study observed 400 Vitamin D deficient people who were overweight and obese.  These 400 participants were placed on low-calorie diets and divided into three groups: one group took no Vitamin D supplements, while two other groups did use Vitamin D supplements at different doses between the two groups.  Results after six months demonstrated that participants in both of the Vitamin D supplementation groups lost more weight and achieved greater reduction in waist circumference than those who had not used Vitamin D supplements.  The researchers wrote, “… in obese and overweight people with Vitamin D deficiency, Vitamin D supplementation aids weight loss and enhances the beneficial effects of a reduced-calorie diet”.  It is prudent for anybody attempting healthy weight loss to monitor and optimize their Vitamin D levels.

Low levels of Vitamin D are also “significantly and independently associated with low levels of testosterone in otherwise healthy middle-aged men”.  A study presented at the 2015 Annual Meeting of the American Urological Association found that total testosterone was higher in men with normal levels of Vitamin D than in men with insufficient levels of Vitamin D.  One of the researchers explained, “this suggests that there is something about testosterone synthesis that needs Vitamin D”.

A March 2015 study published in the Psychiatry Research journal suggests that Vitamin D levels may even be predictive of depression.  Researchers studied 185 female college students in the United States Pacific Northwest.  Although this study did not establish a causal relationship, the researchers conclude that “Vitamin D deficiency and insufficiency occur at high rates in healthy young women, and lower Vitamin D3 levels are related to clinically significant depressive symptoms”.  The researchers warn that Vitamin D should not be considered as a stand-alone treatment for depression but Vitamin D status should be considered and addressed.

This discussion could go on and on.  There is an enormous and growing body of research regarding the functions and importance of Vitamin D.  Research suggests that Vitamin D deficiency is involved in a wide assortment of diseases including various cancers, cardiovascular disease, autoimmune disorders, periodontal disease, migraine headaches, and more.

Alarmingly, Vitamin D insufficiency or outright deficiency is rampant even in developed “first-world” nations like the United States.  Even in our very sunny corner of North Carolina, the initial blood test for patients in my office commonly demonstrates deficient, insufficient or suboptimal Vitamin D status.    Most experts agree that vitamin D sufficiency is above 30 ng/mL (75 nmol/L), an insufficient level is between 20 and 30 ng/mL (50 to 75 nmol/L), and a deficient level is any value below 20 ng/mL (50 nmol/L).  The optimal range for disease protection is 50 – 70 ng/mL.  The NHANES III study revealed that 77% of American adults have deficient or insufficient Vitamin D levels.

A study published just this year in the journal, Nutrients, affirms that Vitamin D deficiency is much more widespread than had been previously recognized.  These researchers assert that the Recommended Dietary Allowance (RDA) for Vitamin D is 10 times lower than what we actually need.  The current RDA is 600 IU per day for adults and children and 800 IU per day for seniors above age 70.  However, these scientists stated that “calculations by us and other researchers have shown that these doses are only about one-tenth those needed to cut incidence of disease related to Vitamin D deficiency” and “this intake is well below the upper level specified by the Institute of Medicine as safe for teens and adults … “.  The Institute of Medicine which helps to establish RDA says that up to 10,000 IU/day is the safe upper limit for teens and adults.

Discussion of a safe upper limit naturally raises concern over excessive or toxic levels of consumption.  However, a 2015 study from the Mayo Clinic Proceedings suggests that Vitamin D toxicity is extremely rare.  In an editorial accompanying the study, Dr. Michael Holick of Boston University wrote that “the evidence is clear that Vitamin D toxicity is one of the rarest medical conditions and is typically due to intentional or inadvertent intake of extremely high doses of Vitamin D (usually in the range of 50,000 – 100,000 IU/day for months to years”.

There are also other ways, in addition to supplementation, to boost your Vitamin D levels.  For instance, sun exposure (especially 15 minutes daily in the sun without sunscreen between the hours of 10:00 and 3:00) helps the body to produce Vitamin D.  Dietary sources of Vitamin D include fatty fish (such as salmon and tuna), fish liver oils, beef liver, cheese, egg yolks, and some mushrooms.  Additionally, the food industry fortifies various foods with Vitamin D; for example, in the United States almost all milk, many breakfast cereals and bottled orange juice are fortified with Vitamin D.

While it is wise to employ these sun exposure and dietary strategies, for most people it will still be necessary to also use supplements in order to achieve optimal Vitamin D status.  It is best to consult your healthcare provider for guidance regarding your Vitamin D status.  For patients in our practice, we recommend twice yearly blood testing to monitor Vitamin D levels and to appropriately manage supplementation.