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Vitamin D facts and statistics

Wondering if you’re getting enough vitamin D? Discover deficiency symptoms, who’s most at risk, the benefits of supplements, and how much is too much.
Rebecca Rovenstine writer headshot
By | Jul. 7, 2025 Medically reviewed by Anne Jacobson, MD, MPH
Bar chart on a clipboard: Vitamin D facts and statistics

Key takeaways

  • In the United States, approximately 1 in 4 people have vitamin D levels that are too low for bone health and overall health.

  • A 25-hydroxyvitamin D, also known as 25(OH)D, blood test can determine if patients have a vitamin D deficiency.

  • Vitamin D supplements are a good option to treat vitamin D deficiency, and vitamin D3 has been found to be more effective than vitamin D2.

  • Vitamin D supplementation isn’t recommended for everyone, and can have side effects at doses that are too high.

In this article:

You’ve probably heard the importance of eating your daily fruits and vegetables, and that’s because they provide many of the nutrients your body needs, like the 13 essential vitamins. One of these essential vitamins, meaning it’s required to survive and remain healthy, is Vitamin D. 

“Vitamin D is a fat-soluble vitamin that plays an important role in the regulation of calcium and phosphorus, which are very important for building, maintaining, and regulating healthy teeth and bones,” explained Dr. Sandip Sachar, a general and cosmetic dentist in Manhattan with over 20 years of experience.

One unique thing about Vitamin D is that it’s found in fewer foods than most other essential nutrients and minerals. The body can also make Vitamin D when skin is exposed to sunlight. But many people don’t get enough Vitamin D through foods or sunlight. As a result, it’s not uncommon to have a Vitamin D deficiency. 

We’ve rounded up helpful information about this essential nutrient, including interviews with healthcare professionals, statistics on vitamin D, and ways to treat Vitamin D deficiency.

How many people are vitamin D deficient?

“Vitamin D deficiency is far more common than people think, particularly in people with darker skin, those who wear sunscreen regularly (as they should), and anyone living in northern climates, or those with minimal sun exposure,” said Dr. Uma Darji, a family physician practicing in North Carolina.

  • In the United States, approximately 1 in 4 people have vitamin D levels that are too low for bone health and overall health. (National Institutes of Health, 2022)

Those with a vitamin D deficiency may experience symptoms that include:

  • Muscle weakness
  • Musculoskeletal pain
  • Fatigue
  • Mood changes

“As a dentist, I am sometimes the first medical provider to notice patients with symptoms that are red flags for vitamin D deficiency,” said Dr. Sachar. She explained, “Signs and symptoms that I often see in my practice are increased gum inflammation, periodontitis, delayed healing after dental procedures, recurrent oral infections, and increased bone loss due to periodontal disease.”

After an extended period, there can be much more severe vitamin D deficiency symptoms, including:

  • Nutritional rickets (soft bones) in children
  • Osteomalacia (soft bones) in adults
  • Worsening osteoporosis in older adults 

Back in the 1930s, as part of a public health initiative, milk began being fortified with vitamin D throughout North America to prevent rickets in children (StatPearls, 2025). Today, fortification of vitamin D in breakfast cereals and milk continues to be a popular practice.

For those suspected of having a deficiency, a vitamin D level can be assessed through a blood test. 

“I often tell patients: If you feel run-down, achy, or just off, it’s worth checking your vitamin D levels. It’s a simple blood test that can offer major insight,” explained Dr. Darji.

  • The most common test for vitamin D insufficiency is called a 25-hydroxyvitamin D, also known as 25(OH)D.
  • According to the National Institutes of Health, serum concentrations of 25(OH)D are reported in both nanomoles per liter (nmol/L) and nanograms per milliliter (ng/mL).
  • Blood levels of 20 ng/mL to 50 ng/mL of 25(OH)D (vitamin D) are considered within the normal range for healthy individuals. Blood levels below 12 ng/mL indicate a vitamin D deficiency. Levels that are between 12 and 20 are considered low for adequate health. (NIH, 2024)

Here are some more facts about Vitamin D deficiencies:

  • In 2012, the Centers for Disease Control (CDC) conducted a nationwide National Health and Nutrition Examination Survey, which found that vitamin D levels typically decrease as people age. While males and females had similar levels, non-Hispanic Black populations had the lowest vitamin D levels, and non-Hispanic white populations had the highest levels. (CDC, 2012)
  • Those most at risk of vitamin D deficiency include older adults, obese people, breastfed infants, people with darker skin pigment , those who consistently cover most of their skin while outside, nursing home residents, and hospitalized patients. (StatPearls, 2025)
  • In the United States, it’s estimated that 50% to 60% of nursing home residents and hospitalized patients are vitamin D deficient. (Mayo Clinic Proceedings, 2010)
  • Those who take oral steroids regularly have been found to have lower blood levels of vitamin D. (NIH, 2024)
  • “Studies have shown that decreased vitamin D levels have been linked to increased risk of tooth loss in older adults. Also, children with inadequate vitamin D levels are more prone to delayed tooth eruption, tooth enamel defects, and increased risk of cavities,” said Dr. Sachar.

How many people take vitamin D supplements?

Treating and preventing Vitamin D deficiency usually involves a supplement. When it comes to supplement use:

  • An analysis of data from 2015 to 2016 found that 28% of individuals in the United States, ages two years and older, took a dietary supplement containing vitamin D. (NIH, 2024)
  • For those taking the supplements, vitamin D intakes were ten times higher when compared to diet alone. (What We Eat in America, 2019).

In the past 10 to 20 years, vitamin D testing has become more common. Back in 2014, it was reported that vitamin D testing for Medicare patients was the fifth most common lab test ordered (American Family Physician, 2018). That being said, routine supplementation has not been shown to decrease the rate of fractures or chronic diseases.

As testing increases, more people are being identified with this condition, which has, in turn, increased the popularity of vitamin D supplements.

Despite the increase in testing and more people being identified, the Endocrine Society only recommends routine vitamin D supplementation for children and teens, people who are pregnant or pre-diabetic, and adults over 75 years, but not for healthy adults ages 19 to 74. Additionally, the American Academy of Pediatrics recommends Vitamin D drops for infants who are completely or partially breastfed, or who don’t drink formula with Vitamin D supplementation. (NIH, 2024)

How effective are vitamin D supplements? 

When talking about vitamin D supplements, it’s important to understand that there are two types of vitamin D available. This includes: 

  • Vitamin D2 (ergocalciferol): This is a human-made vitamin D, which is added to foods, such as milk and cereal.
  • Vitamin D3 (cholecalciferol): This type of vitamin D comes from the sun or is found in foods, which are mostly animal-based, including fatty fish and fish liver oils.

“Vitamin D supplements are usually effective, especially if you’ve been diagnosed with a deficiency,” said Dr. Darji. She added, “I generally recommend vitamin D3, as it’s better absorbed than D2.”

When it comes to statistics about vitamin D supplements and their effectiveness, here are the facts: 

  • In 2012, a meta-analysis looking at decades of research found “vitamin D3 had a significant and positive effect in the raising of serum 25(OH)D concentrations compared with the effect of vitamin D2.” (The American Journal of Clinical Nutrition, 2012)
  • A more recent 2021 meta-analysis confirmed that vitamin D3 supplementation raises vitamin D levels significantly more than supplementation with vitamin D2. (Nutrients, 2021)
  • The American Association of Clinical Endocrinologists recommends supplementation with Vitamin D2 or D3 for people who have a deficiency. (American Association of Clinical Endocrinologists, 2019)

Another effective and natural way to get more vitamin D is with sunlight exposure. Many experts recommend 5 to 30 minutes without sunscreen at least twice a week. Longer sun exposure requires sunscreen to decrease the risk of skin cancer (NIH, 2024). 

There has also been more research into the effect of vitamin D on overall health. While there have been some studies that have shown benefits in preventing or treating conditions like cardiovascular disease, cancer, and depression, these benefits have not been supported in other studies. Further studies are needed to support these claims.

If you want to add more Vitamin D with supplements to support bone health, the suggested daily intake is 400 to 800 international units (IU) for adults (J Steroid Biochem Mol Biol, 2018). 

A panel of global experts doesn’t recommend routine supplementation for healthy adults younger than 75 (The Journal of Clinical Endocrinology and Metabolism, 2024). However, they do recommend supplementation for:

  • Children and adolescents 
  • Adults over 75
  • Pregnant women
  • People with high-risk pre-diabetes

The dose for supplementation will vary based on age and health condition.

How much do Americans spend on vitamin D supplements?

While the exact amount spent on vitamin D supplements in the United States is unknown, it was estimated that Americans spent an estimated $55.7 billion on dietary supplements in 2020 alone. (National Institutes of Health, 2021)

How many Americans use insurance for vitamin D supplements?

When taken as a supplement without a prescription, Vitamin D is typically not covered by insurance. There are a few Medicaid plans in various states that will help cover over-the-counter costs for the supplements.

“Over-the-counter supplements typically aren’t covered, but if you need a prescription-strength dose due to a deficiency, some plans will cover it. This is not generally a medication that insurance companies deny for my patients,” said Dr. Darji.

How many Americans pay for vitamin D out of pocket?

Since very few Americans have insurance plans that cover the cost of vitamin D when taken as a supplement, the majority of Americans pay out of pocket. While we don’t know the exact figures, paying out of pocket is the more common scenario for patients purchasing vitamin D supplements.

Vitamin D side effects

In general, vitamin D supplements are safe when taken at recommended doses. However, you can take too much vitamin D. 

When taken in larger doses, usually over 4,000 IU a day for a longer period of time, vitamin D can be harmful. This could result in vitamin D toxicity, which causes hypercalcemia, where calcium levels in the blood are too high.

Symptoms of taking too much Vitamin D can include:

  • Upset stomach
  • Loss of appetite
  • Weakness and fatigue
  • Brain fog
  • Kidney damage
  • Headache
  • Irritability
  • Low blood count
  • Osteoporosis
  • Slow growth in children

Talk to your healthcare provider before beginning any new vitamin or supplement routine, and follow the recommended doses for your health condition.