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 Benefits: Why This Nutrient Is Important
Vitamin D is a hard-working nutrient that has multiple functions, including:
— Promotes calcium and phosphorus absorption to maintain bone strength and reduce the risk of osteoporosis.
— Supports immune health and helps control infections.
— Reduces inflammation.
— Regulates blood sugar levels.
— Supports muscles and nerves.
— May reduce the risk of autoimmune diseases, such as rheumatoid arthritis and psoriasis.
[SEE: Best Vitamins and Minerals for Older Adults.]
How Much Vitamin D Do You Need?
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.
| Age Group | Vitamin D RDA |
| 0-12 months | 10 mcg/400 IU |
| 1-70 years | 15 mcg/600 IU |
| 70+ years | 20 mcg/800 IU |
[Read: Vitamins for Stress: Do They Work?]
Incidence of Vitamin D Deficiency
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.
Vitamin D Deficiency Causes
What can lead to a vitamin D deficiency?
— Dietary choices.
— Environment.
— Medical conditions.
— Surgery or medication.
Dietary choices
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.
Environment
Certain environmental factors could increase your risk of a vitamin D deficiency, including:
— Lack of outdoor activity. If you spend most of the day indoors, you’ll miss out on opportunities to get vitamin D from the sun.
— Sunblock. Using sunscreen to protect against harmful UV rays limits the skin’s ability to make vitamin D.
— Geographic location. If you live farther away from the equator, you probably have less exposure to the type of sunlight that promotes vitamin D production in the skin.
Medical conditions
Certain medical conditions may interfere with vitamin D absorption, including:
— Ulcerative colitis.
— Cystic fibrosis.
Surgery or medication
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:
— Laxatives.
— Cholesterol-lowering drugs.
— Steroids.
— Genetics. Some people have gene variants that make it hard for their bodies to produce vitamin D, even if their skin is exposed to ultraviolet light.
[See: 11 Pre-Surgery Tips to Boost Recovery.]
Who Is at Risk of Low Vitamin D?
Some people are more likely than others to have trouble getting enough vitamin D. Here are the factors that may determine your risk:
— Age. The skin’s ability to make vitamin when exposed to sunlight declines as you age. This is one reason why higher vitamin D amounts are recommended for adults over age 70. Infants are also at risk of not getting enough vitamin D, especially breastfed babies since breast milk contains only a small about of vitamin D compared to infant formula, which is fortified with vitamin D.
— Mobility. People who are homebound or rarely go outside, such as those who are hospitalized or in nursing homes, may not be able to use sun exposure as a source of vitamin D.
— Skin color. The darker your skin, the less vitamin D you make from sunlight exposure. For example, African Americans and Hispanic people tend to have lower vitamin D levels.
— Weight. A body mass index of 30 or greater is considered a risk factor. Some of the vitamin D can bind to body fat instead of getting into the bloodstream.
— Restricted diets. People who are vegan or follow a 100% plant-based diet may struggle to get enough vitamin D because many of the best sources of vitamin D are from animals, such as dairy and fish.
Best Sources of Vitamin D
To increase daily vitamin D, there are four main sources:
— Foods naturally rich in vitamin D. Fatty fish like salmon and tuna, egg yolks, beef liver, cod liver oil and mushrooms that have been exposed to UV light in the growing process are naturally rich in the vitamin.
— Vitamin D fortified foods. Dairy and non-dairy milk, orange juice and breakfast cereals are sometimes fortified with additional vitamin D.
— Supplements. Vitamin D supplements can help ensure you’re getting adequate amounts each day. Vitamin D3 or cholecalciferol is the preferred form.
— Sunlight. About 20 minutes of unprotected sun exposure each day will help your body make adequate amounts of vitamin D.
Signs of Vitamin D Deficiency
You may not always have symptoms with a vitamin D deficiency. However, these are some of the early signs:
1. Fatigue.
2. Mood changes.
3. More frequent infections and illnesses.
4. Muscle twitching, weakness or pain.
5. Bone pain.
6. Joint stiffness or arthralgias.
7. Lower back pain.
Potential Complications of Low Vitamin D
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:
— Bone fragility and osteoporosis.
— Falls and fractures.
— Increased risk of death from cardiovascular disease.
— Cognitive impairment in older adults.
— Depression.
— Pregnancy complications.
— Certain cancers, including breast, prostate and colon.
When to See a Doctor
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:
— Nursing home residents.
— Hospitalized patients.
— Adults over 65.
— Women with osteoporosis.
— African American and Hispanic individuals.
— People with chronic kidney disease, chronic liver disease and malabsorption syndromes.
What to Do If You’re Vitamin D Deficient
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.
Vitamin D Supplement Side Effects
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:
— Nausea and vomiting.
— Abdominal pain.
— Confusion.
— Weakness.
— Poor appetite.
— Dehydration.
— Constipation.
Vitamin D toxicity could progress to kidney failure and irregular heartbeat or arrhythmias. As always, check with your doctor before taking vitamin D supplements.
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Signs of Vitamin D Deficiency originally appeared on usnews.com
Update 11/30/23: This story was previously published at an earlier date and has been updated with new information.
