Low Vitamin D Levels: Symptoms, Causes, and How to Fight Back

by PJ Hamel Patient Expert

Conservative estimates say that as many as 36% of Americans are vitamin D deficient. And vitamin D is critical for healthy bones. How can you tell if you're lacking vitamin D? Why is your vitamin D level low? And what's the best way to make sure you're getting enough?

Vitamin D works hand in hand with calcium to keep your bones strong; people with low levels of vitamin D fall more often; and they suffer more fractures. When you're battling osteoporosis (or declining bone strength of any kind) and all the challenges that come with it, sufficient vitamin D in your system has to be a critical health consideration.

Beyond bone loss, recent research shows that low levels of vitamin D may also be connected with breast, colon, and prostate cancer; multiple sclerosis; type 2 diabetes; obesity and high blood pressure, and depression.

And if the specter of weakened bones and the previously mentioned health problems aren't enough to get you interested in vitamin D, try this: according to an article on the University of Maryland Medical Center Web site, "Population studies suggest that people with lower levels of vitamin D have a higher risk of dying from any cause compared to those with higher levels of vitamin D."

Have I got your attention?

So, just what is vitamin D deficiency, anyway? According to the National Institutes of Health, if your score on a vitamin D blood test is less than 30, you're "at risk of deficiency." Between 30 and 50 you're considered "at risk of inadequacy;" and over 50 is considered "sufficient for 97.5% of the population."

There are those who'd argue that, given the latest research connecting vitamin D with all kinds of adverse health conditions, the entire scale should be pegged higher, with those scoring under 50 considered vitamin D deficient. But for now, it's safe to go with the NIH's guidelines.

Symptoms of vitamin D deficiency
Vitamin D deficiency can be very sneaky. Most people first learn of it as the result of a blood test. If your annual physical doesn't include screening for vitamin D levels, be sure to ask your doctor
to include it.

Physical symptoms of vitamin D deficiency might include muscle aches and pains; fatigue and lack of energy; sleep problems; depression; lowered resistance to illness, or a surprising bone fracture, e.g., the result of a light fall or other not particularly serious accident.

Pretty vague, right? These symptoms could also be attributable to other health issues. Again, the best way to check for vitamin D deficiency is with a blood test. So if you're experiencing one or more of the symptoms listed, and other causes have been ruled out, ask your doctor to check your vitamin D.

Causes of vitamin D deficiency
What causes vitamin D deficiency? Chiefly, lack of sunlight; and insufficient vitamin D in the diet, either from the foods you eat, or supplements. In addition, as we age our skin gradually thins, and our ability to make vitamin D from sunlight decreases. Thus, older people are naturally at greater risk for vitamin D deficiency.

Steps to ensure adequate vitamin D levels
Sunlight: How much sun should you get to keep your vitamin D level where it should be? Well, it depends where you live; how dark your skin is, and whether you use sun block.

Generally speaking, 15 minutes a day of sun is required for a fair-skinned person; and up to 40 minutes a day for someone with very dark/black skin. This is without sun block; your vitamin D "sunbathing" should happen before 10 a.m. or after 2 p.m., to reduce your risk of sunburn and skin damage.

Unfortunately, if you live above latitude 40 (draw a mental line from Philadelphia to northern California, above Sacramento), it's impossible to get enough sunshine to manufacture sufficient levels of vitamin D between October and April. During these months, the sun is simply too weak; you'll need to beef up vitamin D in your diet, and take a supplement.

Diet: The best source of vitamin D is fish, particularly fatty fish: salmon, tuna, mackerel, herring, and sardines are all high in vitamin D.

The very best dietary source of vitamin D is cod liver oil. Back in the early part of the 20th century, when insufficient vitamin D in children's diets produced the bone disease rickets, youngsters were regularly dosed with cod liver oil.

Can cod liver oil be part of your daily diet? Taste it and see.

Milk is fortified with vitamin D, as are some cereals, cheeses, and other dairy products. Get in the habit of reading labels; if a packaged food is fortified with vitamin D, the manufacturer will no doubt be smart enough to call it out.

Finally, eggs are a good source of vitamin D. And nowadays, since they're no longer the cholesterol villain we thought they were, an egg a day will probably help more than hurt you.

Supplements: The International Osteoporosis Foundation released its new vitamin D recommendations for older men and women this past winter. They're as follows:
-Given sufficient amounts of sunshine, older adults should consume 800 to 1,000 international units (IUs) of vitamin D daily, via diet and/or supplements.
-Older adults who are obese; have osteoporosis; don't get the recommended amount of sunlight, or have problems that prevent them from absorbing vitamin D available in the food they eat need up to 2,000 IUs daily.

Most multivitamins include vitamin D, as do many calcium supplements. In addition, you can take vitamin D alone, in softgel or tablet form. When checking labels, look for vitamin D3 (cholecalciferol); it's the one that's synthesized by sunlight, so even a tiny amount of sun will ensure its fast and complete absorption.

PJ Hamel
Meet Our Writer
PJ Hamel

PJ Hamel is senior digital content editor and food writer at King Arthur Flour, and a James Beard award-winning author. A 16-year breast cancer survivor, her passion is helping women through this devastating disease. She manages a large and active online survivor support network based at her local hospital and shares her wisdom and experience with the greater community via HealthCentral.com.