by Dr. John Neustadt

Vitamin D regulates the functions of more than 200 genes and is one of the most important molecules for our health—so important that the human body produces its own supply daily from the ultraviolet B (UVB) spectrum of sunlight.¹ And yet vitamin D deficiency is rampant in children and adults alike.^2,3 According to two studies that evaluated vitamin D levels in 11,000 people, about 40% of adults and 70% of children are deficient in this crucial nutrient.^4,5 People with malabsorption issues, such as Crohns disease, Ulcerative Colitis and Celiac, and the elderly have even higher risks for vitamin D deficiency.

Since vitamin D affects so many genes, it’s not surprising that vitamin D helps protect us from a whole host of problems. Vitamin D can help us fight infections; help protect against diabetes, heart disease, cancer, asthma, depression, autoimmune diseases like multiple sclerosis (MS) and rheumatoid arthritis (RA); and generally boosts your immune system. Vitamin D increases our absorption of critical vitamins and minerals, including calcium and magnesium. Strong, healthy bones depend on vitamin D. Unfortunately, deficiency of vitamin D is often a “silent disease” with very few obvious symptoms. 

Why Low Vitamin D is So Common

There are several reasons that can explain why so many people are deficient in vitamin D. These days we just don’t get enough steady sunlight, and when we do, we’re either covered up or we slather ourselves with sunblock, preventing UVB from penetrating our skin. To prevent Vitamin D deficiency, it takes fifteen to twenty minutes of sunshine daily with more than 40% of your skin exposed.⁶

If you live in the northern hemisphere above 37 degrees north latitude, in the winter the sun never gets high enough to stimulate our own vitamin D production.⁷ 

Where exactly is that? Thirty-seven degrees is an imaginary line that passes through California (near Santa Cruz), Nevada, southern Utah, northern Arizona, along the Colorado/New Mexico border, and through the Kansas/Oklahoma border, Missouri, southern Illinois, Kentucky and Virginia. So if you live in those areas, or north of them, in the winter your risk for vitamin D deficiency is higher than your neighbors to the south.

Darker skin, which contains relatively more melanin than lighter skin, slows the production of vitamin D. Similarly, aging reduces skin vitamin D production. Common glass in home or car windows and clothing all reduce UVB radiation exposure, even in summer months.

One Powerful Nutrient

Vitamin D deficiency is a serious health threat that needs to be on everyone’s radar. Vitamin D deficiency not only causes rickets among children but also osteoporosis among adults and causes the painful bone disease osteomalacia. Vitamin D deficiency has been associated with increased risks of deadly cancers, cardiovascular disease, multiple sclerosis, depression, schizophrenia, rheumatoid arthritis, and type 1 diabetes mellitus.^8,9

Inflammation and Autoimmune Diseases

Studies show that vitamin D helps render the immune system more tolerant and less reactive, reducing the levels of pro-inflammatory molecules produced by immune cells. Since inflammation fuels the “fire” of autoimmune disease, vitamin D can be helpful.¹⁰ 

Clear connections can be seen between vitamin D deficiency and numerous autoimmune disorders like multiple sclerosis, Crohn’s disease and diabetes.^11,12 A review of ten studies on vitamin D found that the vitamin improves insulin resistance and lowers the risk of diabetes.¹³

In those who suffer from Crohn’s disease, it has long been recognized that vitamin D deficiency is likely because of malabsorption, but more recently studies have suggested that deficiency can contribute to the disease and that supplementation is beneficial. A study in 2016 of 94 Crohn’s patients who were in remission found that vitamin D supplementation slashed the relapse rate; a second study found that “leaky gut” was improved in those who took vitamin D.¹⁴  Vitamin D has also been found beneficial in multiple sclerosis in Caucasians—a study of 148 MS patients and 296 healthy individuals found that the risk of MS significantly decreased as levels of vitamin D increased.¹⁵

Cancers

Research indicates vitamin D deficiency has been associated with increased risk for dying from cancers, including breast, uterine, prostate and colon cancers, as well as for getting heart disease, stroke, autoimmune diseases, birth defects, periodontal disease and infections.^16,17

Vitamin D is so important to health that a 2008 study found low blood levels were associated with double the risk of death overall.¹⁸ This trend was confirmed by a larger study that showed a significant reduction in cancer mortality with vitamin D3 supplementation.¹⁹ 

Healthy Mood

Globally, it’s estimated that 350 million people suffer from depression.²⁰ While depression is a complex condition with many potential causes, including low iron, low testosterone and poor sleep, supplementation with vitamin D has been found beneficial for those who have a diagnosis of clinical depression.²¹ A 2013 study found more than twice the risk of depression in those with low vitamin D levels compared to the general population.²² Mood can be boosted as well by supplementing with vitamin D in those with fibromyalgia, diabetes, obesity or even simply old age.^23-25  

Heart Health

Low vitamin D is linked to heart disease. Vitamin D deficiency has been linked to vascular dysfunction; arterial stiffening; hypertension, and high cholesterol—as well as a greater risk of cardiovascular problems and death.²⁶ Coronary artery disease to heart attack, heart failure, atherosclerosis and hypertension are linked to vitamin D deficiency.^27,28 Research shows that vitamin D plays a critical role in preserving and even restoring the function of the endothelium—the protective inner lining of our blood vessels, from our largest artery to our smallest capillary.²⁹

Bone Health and Fractures

When most people think about an osteoporosis dietary supplement they right away think of calcium and vitamin D. In fact, the FDA has approved calcium and vitamin D to “reduce osteoporosis risk.” The most dangerous risk with osteoporosis is fracturing a bone. Fortunately, adequate levels of vitamin D are associated with increased bone mineral density and a reduced risk of bone fracture, especially as we age.³⁰ 

Several studies have evaluated how powerful vitamin D and calcium are for reducing fractures. One study found a modest 16% reduction in fracture risk over 3 years in 2532 community-dwelling residents (average age, 73 years; 59.8% female) who supplemented with 400 IU vitamin D3 and 1000 mg calcium daily.²⁹

Vitamin D Testing and Optimal Levels

Far too many of my patients suffered from low vitamin D levels, but most didn’t realize their vitamin D was low. Because I know how crucial this vitamin is to optimal health, testing vitamin D was commonly done in my clinical practice. Vitamin D testing is as easy as a simple blood draw, often available alongside other routine blood work or testing. 

Oral supplementation of 2,000-5,000 IU/day (50-125 micrograms per day) is generally well-tolerated.³¹ In 2011 the Institute of Medicine suggested the level needed for good bone health for most individuals is 20 nanograms per mL (ng/mL).³²

However, other researchers have concluded that higher levels are even better. To reduce the risks for falls and fractures, a person’s Vitamin D blood concentration should be 30-44 ng/mL. Above 30 ng/mL, nonvertebral fractures decrease by 20% and hip fractures by 18%. Similarly, the greatest decrease in the risk for falling is seen when someone’s vitamin D level is about 30 ng/mL, and dying from any cause was reduced when the blood level was 40-48 ng/mL.³³

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