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More Than a Third of U.S. Adults Are Vitamin D Deficient: Are You?

According to this study, a whopping 36% of healthy adults and up to 57% of general medicine inpatients in the U.S. dont get enough vitamin D.

more than a third of u.s. adults are vitamin d deficient are you sun and yellow umbrella

Vitamin D Deficiency Risk Factors

Factor 1: Low sun exposure

Vitamin D is made in the skin through sun exposure. This relationship between sun exposure and bone strength was first observed by the ancient Greek historian Herodotus in 525 BC. He noted that the skulls of Egyptians (who had ample sun exposure) were far stronger than those of Persians (who covered themselves). Now, of course, we have more than a mere correlation.

Vitamin D metabolism from precision nutrition
If you’re curious, here’s how we now know the sunlight -> vitamin D process works:

Cells in your skin already have a precursor (called 7-dehydrocholesterol) that sunlight converts into previtamin D3. The vitamin Dthen leaves your cells and enters your circulatory system, bound to a protein (vitamin D binding protein, DBP). There it floats around until it is stored in fat cells or turned into another form (called 25-hydroxyvitamin D). Next, it goes to the kidneys for conversion to the active hormonal form (calcitriol), where it can start to help out various body systems.

Geographic location is critical to overall sun exposure because it determines how much sun you can get in a day. If you live in a climate that has a very cold winter, going outside with exposed skin isn’t really an option. The shorter days in colder climates definitely don’t help.

Low sun exposure can also occur if you don’t go outside enough, period. Or, if you tend to consistently slather on high SPF sunscreen.

Factor 2: Low Vitamin D in the diet

mushrooms contain vitamin d

Unfortunately, vitamin D is difficult to get from food alone.

  • Found in: Fatty fish like cod, salmon, and tuna. Mushrooms, egg yokes, and fortified cereals, juices, and dairy products (see NIH list here). And, of course, in vitamin D supplements.

Other factors that contribute to your personal risk of vitamin D deficiency:

Why Does Vitamin D Matter?

xray vitamin d bone health
Vitamin D deficiency is problematic because the so-called “sunshine vitamin” plays important roles in immune, bone, and skin health.

Five symptoms of Vitamin D deficiency

1) Poor healing or frequently getting sick

Vitamin D is necessary for optimal immune function, and therefore deficiency can lead to both wounds and sicknesses hanging around for longer. This study (of 19,000 people) found that people with low vitamin D were more likely to suffer from the common cold.

2) Fatigue

This study showed that in patients who suffered from fatigue, 77% were deficient. Their fatigue symptoms were significantly improved through vitamin D therapy.

3) Bone-related pain, mass loss, or fractures

According to this study, low vitamin D prematurely ages bones, leading to a 22-31% increase in the start and spread of fractures.

4) Depression and/or low mood

Though more research is necessary, some individuals with depression (or seasonal affective disorder) experience an improvement in symptoms following vitamin D increase (either through supplementation or light therapy). Review here.

5) Muscle pain or strong muscle soreness that is slow to improve

Pain-sensing nerves (in rats and humans) actually have vitamin D receptors. As a result, this study in rats showed that muscle pain could be brought on by vitamin D deficiency. Individuals suffering from chronic pain and conditions like fibromyalgia can sometimes find some relief from supplementing vitamin D.

Unfortunately, these symptoms are all very general, so the only sure-fire way to find out if you’re vitamin D deficient is to do a blood test. The blood test will look at your levels of a particular vitamin D precursor (25-hydroxyvitamin D) that’s easy to find and measure.

You can always try supplementing it, getting more sun, or eating more vitamin D-rich foods. Keep track of any changes to your symptoms.

Has vitamin D supplementation helped improve any of your ailments? Did you have any “light-bulb” moments reading this article? Let us know in the comments below.