What Percentage of the US Population Is Vitamin D Deficient?

December 25, 2025 •

3 min read

According to research from the Cleveland Clinic, approximately 35% of adults in the United States are vitamin D deficient. This common nutritional shortfall can have significant health implications, impacting everything from bone density to immune function.

Quick Summary

An estimated 35% of US adults are vitamin D deficient, with significant variations across demographics. Factors like race, age, and lifestyle can heavily influence individual risk, highlighting the widespread nature of this public health concern.

Key Points

High Prevalence: Approximately 35% of US adults are vitamin D deficient, according to Cleveland Clinic, and data from the NIH indicates widespread inadequacy.
Racial Disparities: Non-Hispanic African-Americans and Asians have significantly higher rates of deficiency than non-Hispanic White populations, due primarily to skin pigmentation.
Risk Factors: Key contributors include limited sun exposure, darker skin, older age, obesity, certain medical conditions, and dietary choices.
Serious Consequences: Chronic deficiency can lead to bone disorders like osteomalacia and osteoporosis, and is associated with chronic conditions like cardiovascular disease.
Treatment and Prevention: Strategies include controlled sun exposure, eating fortified and vitamin D-rich foods, and taking supplements, with medical guidance being crucial.
Older Adults at Risk: Declining skin synthesis and other factors make adults over 65 a particularly high-risk demographic for deficiency.

Prevalence of Vitamin D Deficiency in the US

Official statistics from authoritative sources indicate a significant prevalence of vitamin D deficiency and insufficiency within the United States population. For example, an analysis of 2011–2014 NHANES data by the NIH Office of Dietary Supplements found that 5% of Americans aged 1 and older were at risk of deficiency (serum levels below 12 ng/mL), with an additional 18% at risk of inadequacy (levels between 12 and 19.6 ng/mL). The Cleveland Clinic reports a more striking figure, suggesting approximately 35% of US adults have a full-blown deficiency. These figures fluctuate based on the specific studies and the thresholds used to define deficiency, but they consistently reveal a widespread public health issue.

Demographic Disparities in Vitamin D Levels

Certain populations are disproportionately affected by low vitamin D levels due to a variety of factors, from skin pigmentation to lifestyle. A 2011-2012 NHANES analysis showed stark racial differences, with non-Hispanic African-Americans exhibiting a much higher prevalence of deficiency compared to non-Hispanic White individuals. This is primarily because darker skin contains more melanin, which acts as a natural sunscreen and inhibits the skin's ability to produce vitamin D from sunlight. Older adults also face higher risks, as skin synthesis of vitamin D declines with age. Other groups, including those with limited sun exposure, certain health conditions like obesity, and malabsorption syndromes, are also at an elevated risk.

Causes and Risk Factors for Low Vitamin D

Multiple factors contribute to the prevalence of vitamin D deficiency, emphasizing the importance of a multifaceted approach to prevention.

Insufficient Sun Exposure: Sunlight is the primary way our bodies produce vitamin D. Geographical location, season, and regular use of sunscreen can all limit this crucial exposure.
Dietary Habits: While limited foods naturally contain vitamin D, a diet lacking fortified foods (like milk and cereals) or rich sources (fatty fish) is a major contributor.
Medical Conditions: Certain medical issues can interfere with vitamin D absorption or metabolism. These include Crohn's disease, celiac disease, and gastric bypass surgery.
Age: The body's ability to synthesize vitamin D from sunlight diminishes with age, making older adults more susceptible.
Darker Skin Pigmentation: Higher melanin levels in darker skin significantly reduce the efficiency of vitamin D production from sun exposure.
Obesity: Vitamin D is a fat-soluble vitamin. In individuals with obesity, excess body fat can sequester the vitamin, preventing it from circulating in the blood.

Comparison of Vitamin D Status by Demographic

To illustrate the disparities, here is a comparison based on NHANES 2011–2014 data concerning the risk of deficiency (serum levels <12 ng/mL):


Population Subgroup	Percentage at Risk of Deficiency	Key Contributing Factor
Non-Hispanic Black	17.5%	Higher melanin content in skin
Non-Hispanic Asian	7.6%	Increased skin pigmentation, variable sun exposure
Hispanic	5.9%	Variable sun exposure, cultural factors
Non-Hispanic White	2.1%	Generally lower risk, higher sun exposure
Adults (20-39 years)	7.6%	Lifestyle factors, indoor occupations
Adults (>60 years)	2.9%	Reduced skin synthesis with age

Addressing and Preventing Vitamin D Deficiency

Treating and preventing deficiency involves a combination of sun exposure, diet, and supplementation. Healthcare providers can conduct blood tests to measure serum vitamin D levels and recommend an appropriate course of action.

Strategic Sun Exposure: Controlled, moderate sun exposure is a natural way to boost levels. However, it's crucial to balance this with skin cancer risk, especially for those with fair skin.
Dietary Adjustments: Incorporating vitamin D-rich foods is beneficial. These include fatty fish (salmon, tuna), egg yolks, and fortified products like milk, cereals, and orange juice.
Supplementation: For many, especially those in high-risk groups, supplements are the most effective way to correct and maintain healthy vitamin D levels. The form (D2 or D3) and dosage should be determined in consultation with a doctor. For more information on recommended dosages, refer to health professional fact sheets from the National Institutes of Health.

Conclusion

Vitamin D deficiency represents a significant public health issue in the US, affecting millions and having profound impacts on skeletal, muscular, and immune health. While overall statistics indicate a substantial prevalence, certain groups face much higher risks due to demographic and lifestyle factors. A proactive approach involving strategic sun exposure, dietary changes, and, most importantly, medical consultation and targeted supplementation can effectively address this deficiency and mitigate its long-term health consequences. Awareness and regular monitoring are key, particularly for those in high-risk categories, to prevent this widespread yet often overlooked nutritional problem.

Frequently Asked Questions

According to the NIH Office of Dietary Supplements, a serum 25(OH)D level of 20 ng/mL or higher is generally considered sufficient for bone and overall health in healthy individuals.

Darker skin has higher concentrations of melanin, a pigment that protects the skin from UV radiation. This effectively reduces the skin's ability to produce vitamin D from sunlight, leading to a higher risk of deficiency.

It is difficult to get enough vitamin D from diet alone, as only a few foods naturally contain significant amounts. These include fatty fish and egg yolks, but many people rely on fortified foods like milk and cereals to meet their needs.

As people age, their skin's ability to synthesize vitamin D from sunlight decreases. For individuals with obesity, excess body fat can sequester vitamin D, making less available for use by the body.

Common symptoms can be subtle and may include fatigue, bone pain, muscle weakness, frequent infections, hair loss, and mood changes like depression.

While both are used as supplements, studies have shown that vitamin D3 (cholecalciferol), which comes from animal sources, is more effective at raising and maintaining serum vitamin D levels than vitamin D2 (ergocalciferol).

Treatment usually involves increasing intake through supplements (D2 or D3), dietary adjustments, and controlled sun exposure, all under the guidance of a healthcare professional.