Low Vitamin D Symptoms: 7 Ways to Spot Vitamin D Deficiency

Vitamin D is considered a nutrient of public health concern, meaning that a staggering number of people don’t get enough of this vitamin in their diet. If you think your diet may be low in vitamin D, learn about the signs and symptoms of a vitamin D deficiency and how you can easily increase your intake.

Known as the “sunshine vitamin” because our body can make its own vitamin D when sunlight hits our skin, vitamin D plays a critical role in keeping us healthy.

Vitamin D is a hard-working nutrient that has multiple functions, including:

The amount of vitamin D you need each day depends on your age. You’ll see vitamin D listed as international units (IU) and micrograms (mcg). The recommended dietary allowance, or RDA, for vitamin D is 600 IU or 15 mcg for children and young adults. After age 70, the RDA increases to 800 IU or 20 mcg per day.

Other experts suggest we need even more vitamin D. For example, the Endocrine Society recommends up to 1,500 to 2,000 IU of vitamin D daily for adults.

Vitamin D deficiency has been called a global pandemic, impacting 1 billion people worldwide. An analysis of the National Health and Nutrition Examination Survey estimates that about 42% of the U.S. population is deficient in vitamin D.

However, it’s important to remember that a true vitamin deficiency means specific health problems result from the lack of a nutrient. An actual vitamin D deficiency results in rickets, which is the term for a bone-softening, leg-bowing disease that is more likely to impact children in developing countries. Rickets is rare in the U.S.

While many people in the U.S. fail to consume recommended levels of vitamin D, the concerns about severe deficiencies are overblown, says Clifford J. Rosen, MD, director of clinical and translational research and a senior scientist at the Maine Medical Center Research Institute in Scarborough, Maine, who is one of the country’s leading authorities on vitamin D.

The main source of controversy is the different definitions of “deficiency,” according to Rosen, who says various organizations have used different cutoff points for normal vitamin D levels, with some so high that it over-estimates the number of Americans who are truly deficient.

What can lead to a vitamin D deficiency?

Not getting enough vitamin D can be caused by your dietary choices. Few foods are naturally good sources of vitamin D, which makes it more difficult to consume adequate amounts. 

Certain environmental factors could increase your risk of a vitamin D deficiency, including:

Certain medical conditions may interfere with vitamin D absorption, including:

Weight loss surgeries like gastric bypass surgery make it difficult to absorb sufficient quantities of vitamin D. Additionally, some medications can lower vitamin D levels, including:

Some people are more likely than others to have trouble getting enough vitamin D. Here are the factors that may determine your risk:

To increase daily vitamin D, there are four main sources:

You may not always have symptoms with a vitamin D deficiency. However, these are some of the early signs:

If vitamin D deficiency continues for long periods, it may result in complications. Low blood levels of vitamin D have been associated with the following:

If you have these signs and suspect they’re linked to a vitamin D deficiency, talk to your healthcare provider about getting a blood test that can check for vitamin D levels.

The most accurate way to measure vitamin D levels is the 25-hydroxyvitamin D blood test. A vitamin D level less than 20 nanograms/milliliter (ng/mL) is generally accepted as deficient. However, some groups define vitamin D deficiency as less than 30 ng/mL

Even though there’s been increased attention on vitamin D deficiencies – and an estimated 10 million vitamin D blood tests are performed annually – the U.S. Preventive Services Task Force found insufficient evidence to recommend widespread vitamin D testing among healthy adults.

Only high-risk populations are recommended for vitamin D screening, including:

If a lab test reveals low levels of vitamin D, your healthcare provider may recommend supplementation. The safe upper limit for vitamin D supplementation is 4,000 IU or 100 mcg per day, so it’s important not to go over that amount unless recommended by your doctor.

It’s also important not to expect miracles by taking more vitamin D. Even though vitamin D is an essential nutrient, more isn’t always better.

Dr. JoAnn Manson, chief of preventive medicine at Brigham and Women’s Hospital in Harvard Medical School and leader of a large vitamin D randomized trial called VITAL, found that increasing vitamin D did not protect against fractures, heart disease or cancer.

“We only need small to moderate amounts of vitamin D, and among the healthy population, most people do not need screening tests or supplements,” she says. “Larger amounts do not confer greater benefits.”

High doses of vitamin D, however, may benefit the immune system and tamp down inflammation, Manson says. That may be why the VITAL trial found that vitamin D helped lower the risk of autoimmune conditions, such as rheumatoid arthritis and psoriasis, she says.

Unlike vitamins C and B, which are water-soluble vitamins, Vitamin D is a fat-soluble vitamin (along with vitamins A, E and K). This means that vitamin D can be stored in the body and could pose a risk for toxicity when consumed in large amounts.

With the growing consumer interest in vitamin D – and the articles and books extolling the benefits – there’s actually been an increase in vitamin D toxicity. Some of the cases are due to errors, yet much of the blame is due to the widespread availability of high-dose, over-the-counter supplements.

Taking 60,000 IU of vitamin D per day for several months has been shown to cause toxicity. The main consequence is a buildup of calcium in your blood, called hypercalcemia, which can cause several problems:

Vitamin D toxicity could progress to kidney failure and irregular heartbeat or arrhythmias. As always, check with your doctor before taking vitamin D supplements.