Vitamin D deficiency is widespread, with about 1 billion people globally living with low 25(OH)D (<20 ng/mL). In the US, about 42% of adults aged 1+ have levels below 20 ng/mL (2011–2012 NHANES), and risk can be higher with age, darker skin, and limited winter UVB. This page explains how vitamin D is measured, why levels drop, and which foods, fortified options, and supplements can help—along with safety limits.
Key Takeaways
- In the US, 35% of adults have serum 25(OH)D <20 ng/mL indicating deficiency
- Globally, 1 billion people have vitamin D deficiency (<20 ng/mL)
- In Europe, prevalence of 25(OH)D <30 nmol/L is 13% overall, up to 40% in elderly
- The recommended dietary allowance (RDA) for vitamin D in adults aged 19-70 years is 15 micrograms (600 IU) per day
- Vitamin D3 (cholecalciferol) is found in fatty fish like salmon, with 3 ounces providing about 14.2 micrograms (568 IU)
- Fortified milk typically contains 2.5 micrograms (100 IU) of vitamin D per 8-ounce serving in the US
- Human skin exposure to UVB radiation at 290-315 nm wavelengths initiates vitamin D3 synthesis from 7-dehydrocholesterol
- In Boston, from November to February, no vitamin D synthesis occurs even with whole-body exposure to 1 minimal erythemal dose
- Midday summer sun exposure of arms and face for 8-10 minutes allows sufficient vitamin D production for fair-skinned individuals
- Vitamin D deficiency increases risk of falls by 20% in elderly per 10 ng/mL decrease
- Low vitamin D (<20 ng/mL) associated with 2-fold increased risk of type 2 diabetes
- Serum 25(OH)D <30 ng/mL linked to 30% higher all-cause mortality risk
- Daily 800 IU vitamin D3 raises serum 25(OH)D by 10-20 ng/mL in deficient adults
- Upper limit for vitamin D intake is 100 micrograms (4,000 IU) per day for adults
- 50,000 IU weekly for 8 weeks corrects deficiency in 90% of patients
Globally, widespread low vitamin D raises health risks, but adequate intake and sunlight can improve levels.
Related reading
01 · Category
Deficiency Statistics30 stats
01
In the US, 35% of adults have serum 25(OH)D <20 ng/mL indicating deficiency
02
Globally, 1 billion people have vitamin D deficiency (<20 ng/mL)
03
In Europe, prevalence of 25(OH)D <30 nmol/L is 13% overall, up to 40% in elderly
04
42% of US population aged ≥1 year has serum 25(OH)D <20 ng/mL (2011-2012 NHANES)
05
African Americans have 3-fold higher deficiency rates (82.1% <20 ng/mL) vs whites
06
In India, 70-100% of population shows vitamin D deficiency (<20 ng/L)
07
Nursing home residents have 74% prevalence of severe deficiency (<12 ng/mL)
08
Pregnant women worldwide: 79.4% prevalence of 25(OH)D <20 ng/mL
09
Children in northern climates show 20-50% deficiency rates in winter
10
Mexican Americans: 57.1% <20 ng/mL vs 35.4% non-Hispanic whites (NHANES)
11
In UK, 40% adults deficient (<25 nmol/L) per NICE
12
Saudi Arabia: 82% women <20 ng/mL
13
Canada: 32% population <20 ng/mL (2007-2009)
14
US adolescents 12-19: 61% at risk (<20 ng/mL)
15
China urban: 64.2% <20 ng/mL
16
Hospitalized patients: 50% deficient
17
Middle East/N Africa: >80% prevalence <20 ng/mL
18
US obese: 82.5% <30 ng/mL
19
Institutionalized elderly: >50% severe deficiency
20
Latino children US: 82% <20 ng/mL in winter
21
Australia: 23% adults <27.5 nmol/L severe deficiency
22
Turkey: 52.6% <20 ng/mL in general population
23
Finland: 7.2% <30 nmol/L but higher in elderly
24
US elderly ≥65: 26% <20 ng/mL
25
Brazil: 73% <30 ng/mL despite latitude
26
ICU patients: 60-80% deficient
27
South Asia immigrants in UK: 90% deficient
28
Athletes: 50% low levels impacting performance
29
Vegans: 40% higher deficiency risk
30
Schoolchildren Europe: 18% <30 nmol/L
Interpretation
Deficiency Statistics Interpretation
Vitamin D deficiency is widespread and disproportionately affects vulnerable groups, with 35% of US adults (and 42% of Americans aged 1 year and older) having serum 25(OH)D below 20 ng/mL, and African Americans showing markedly higher deficiency rates at 82.1%.
02 · Category
Dietary Sources30 stats
01
The recommended dietary allowance (RDA) for vitamin D in adults aged 19-70 years is 15 micrograms (600 IU) per day
02
Vitamin D3 (cholecalciferol) is found in fatty fish like salmon, with 3 ounces providing about 14.2 micrograms (568 IU)
03
Fortified milk typically contains 2.5 micrograms (100 IU) of vitamin D per 8-ounce serving in the US
04
One large egg yolk provides approximately 1 microgram (40 IU) of vitamin D
05
Beef liver, cooked, 3 ounces, contains about 1.2 micrograms (48 IU) of vitamin D
06
Mushrooms exposed to UV light can provide up to 10 micrograms (400 IU) per 100g serving
07
Cod liver oil, one tablespoon, delivers 34 micrograms (1,360 IU) of vitamin D
08
Fortified orange juice, 8 ounces, often contains 2.5 micrograms (100 IU) of vitamin D
09
Canned sardines in oil, 3 ounces, provide 4.8 micrograms (193 IU) of vitamin D
10
Swiss cheese, 1 ounce, has about 0.3 micrograms (12 IU) of vitamin D
11
Fortified cereals can vary, but some provide 2.5-5 micrograms (100-200 IU) per serving
12
Tuna, canned in water, 3 ounces, contains 1 microgram (40 IU) of vitamin D
13
Yogurt, fortified, 6 ounces, may have 1.5 micrograms (60 IU) of vitamin D
14
Shiitake mushrooms, dried, 1/2 cup, offer 0.4 micrograms (16 IU) of vitamin D
15
Pork fat, 3 ounces, provides 0.7 micrograms (28 IU) of vitamin D
16
Fortified soy milk, 8 ounces, typically has 2.5 micrograms (100 IU) of vitamin D
17
Mackerel, cooked, 3 ounces, contains 10.1 micrograms (405 IU) of vitamin D
18
Ricotta cheese, part-skim, 1/2 cup, has 0.3 micrograms (12 IU) of vitamin D
19
Rainbow trout, farmed, cooked, 3 ounces, provides 14.2 micrograms (568 IU)
20
UV-exposed portobello mushrooms can produce over 1000 IU per 100g
21
The recommended dietary allowance (RDA) for vitamin D in adults aged 19-70 years is 15 micrograms (600 IU) per day
22
Vitamin D3 from salmon provides 447 IU per 3-ounce serving
23
One cup of fortified cow's milk has 115-124 IU vitamin D
24
Egg yolks contain 37 IU vitamin D per large egg
25
85g chicken liver offers 15 IU vitamin D
26
One tablespoon cod liver oil: 1,300 IU vitamin D
27
Fortified almond milk: 100 IU per cup
28
100g canned tuna: 268 IU vitamin D
29
Cheddar cheese: 12 IU per ounce
30
Fortified cereals: up to 200 IU per serving
Interpretation
Dietary Sources Interpretation
From dietary sources, it typically takes about 15 micrograms or 600 IU per day for adults to meet the RDA, which a single 3-ounce serving of salmon can nearly supply with 14.2 micrograms or 568 IU, while foods like fortified milk at 2.5 micrograms per 8 ounces and egg yolk at 1 microgram per yolk contribute smaller amounts that likely need to be combined.
03 · Category
Endogenous Production30 stats
01
Human skin exposure to UVB radiation at 290-315 nm wavelengths initiates vitamin D3 synthesis from 7-dehydrocholesterol
02
In Boston, from November to February, no vitamin D synthesis occurs even with whole-body exposure to 1 minimal erythemal dose
03
Midday summer sun exposure of arms and face for 8-10 minutes allows sufficient vitamin D production for fair-skinned individuals
04
Darker skin requires 3-5 times longer sun exposure for equivalent vitamin D synthesis due to melanin
05
Latitude above 37°N reduces UVB availability, limiting vitamin D synthesis from October to March
06
Sunscreen with SPF 15 reduces vitamin D synthesis by 99% upon sufficient application
07
Aging decreases 7-dehydrocholesterol levels by 75% between ages 20 and 70, impairing synthesis
08
Whole body irradiation with 1 MED produces 10,000-20,000 IU vitamin D3 in light skin
09
Glass blocks UVB rays, preventing vitamin D synthesis through windows
10
Obesity sequesters vitamin D in fat tissue, reducing circulating 25(OH)D by 50% in obese vs normal weight
11
UVB exposure on 25% body surface for 15 min generates 3,000 IU in summer
12
In Miami (25°N), vitamin D synthesis possible year-round with 10-15 min exposure
13
10-15 min midday sun on face/arms produces 1,000-3,000 IU for skin type II
14
Skin type VI (black skin) needs 30-60 min for same production as type II
15
At 42°N (Chicago), synthesis limited Nov-Mar even full body exposure
16
SPF 30 sunscreen reduces synthesis by >95%
17
Precursor 7-DHC declines 65% from age 20 to 80
18
1 MED whole body yields ~25,000 IU in young adults
19
Tanning beds emitting UVB can produce 10,000 IU in 10 min session
20
Clothing coverage reduces production proportionally to skin exposed
21
In Puerto Rico (18°N), synthesis peaks at 15 min exposure year-round
22
Cloud cover reduces UVB by 50%, halving production time needed
23
Morning/afternoon sun less effective; peak 10am-3pm for production
24
Altitude increases UVB by 10% per 1,000m, boosting synthesis
25
Winter in Oslo (60°N): zero synthesis possible
26
Air pollution reduces UVB penetration by 20-50% in urban areas
27
Renal impairment halves 1,25(OH)2D production efficiency
28
Whole-body 20 min sun: 10,000-15,000 IU for type I-III skin
29
Shade reduces production by 50% vs direct sun
30
Hormonal contraceptives lower synthesis by 20%
Interpretation
Endogenous Production Interpretation
For endogenous vitamin D production, UVB-driven synthesis can be so limited by season, latitude, and skin pigmentation that at 37°N and above it drops from October to March and in Boston it produces none from November to February, while darker skin needs 3 to 5 times longer exposure to make up the difference.
04 · Category
Health Outcomes29 stats
01
Vitamin D deficiency increases risk of falls by 20% in elderly per 10 ng/mL decrease
02
Low vitamin D (<20 ng/mL) associated with 2-fold increased risk of type 2 diabetes
03
Serum 25(OH)D <30 ng/mL linked to 30% higher all-cause mortality risk
04
Deficiency correlates with 1.5-fold increased colorectal cancer risk
05
Rickets incidence rises with vitamin D deficiency; 15 cases per 100,000 in high-risk groups
06
Low levels (<12 ng/mL) increase respiratory infections by 40% in children
07
Osteomalacia prevalence up to 20% in veiled Middle Eastern women with deficiency
08
25(OH)D <20 ng/mL associated with 2.3-fold higher depression risk
09
Vitamin D supplementation reduces fracture risk by 20% at doses >800 IU/day
10
Low vitamin D doubles risk of severe COVID-19 outcomes
11
<15 ng/mL increases osteoporosis risk by 2.5-fold
12
Each 10 ng/mL increase reduces CVD mortality by 8%
13
Deficiency linked to 1.7-fold higher breast cancer risk
14
Children deficient have 50% more asthma exacerbations
15
Low levels associated with 30% higher dementia risk
16
Supplementation cuts acute respiratory infections by 12%
17
<20 ng/mL raises autoimmune disease risk by 22%
18
Vitamin D insufficiency (<30 ng/mL) prevalent in 50% multiple sclerosis patients
19
Pregnancy deficiency increases preeclampsia by 2-fold
20
Low vitamin D triples severe asthma risk in kids
21
<10 ng/mL linked to 4-fold hip fracture increase
22
Optimal levels reduce hypertension by 10% per 20 ng/mL rise
23
Deficiency raises pancreatic cancer odds by 1.4
24
Reduces muscle strength by 20% below 20 ng/mL
25
Supplementation lowers cancer mortality by 13%
26
Low D correlates with 25% higher schizophrenia risk
27
Improves insulin sensitivity by 15% with correction
28
Deficiency in IBD patients: 60%, worsens flares
29
Low levels increase periodontitis risk by 0.66 OR
Interpretation
Health Outcomes Interpretation
From a Health Outcomes perspective, vitamin D levels appear to matter substantially since deficiency is linked to outcomes like a 30% higher all cause mortality risk when 25(OH)D falls below 30 ng/mL and a 40% increase in respiratory infections in children when levels drop under 12 ng/mL.
05 · Category
Supplementation Data29 stats
01
Daily 800 IU vitamin D3 raises serum 25(OH)D by 10-20 ng/mL in deficient adults
02
Upper limit for vitamin D intake is 100 micrograms (4,000 IU) per day for adults
03
50,000 IU weekly for 8 weeks corrects deficiency in 90% of patients
04
Vitamin D2 vs D3: D3 is 87% more effective at raising 25(OH)D levels
05
In obese individuals, 2-3 times higher doses needed to achieve same serum levels
06
Infants <12 months: RDA 10 micrograms (400 IU)
07
Elderly >70 years: RDA 20 micrograms (800 IU) daily
08
Hypercalcemia risk increases above 150 ng/mL serum 25(OH)D
09
2,000 IU daily safe and effective for most adults per Endocrine Society
10
4,000 IU/day maintains optimal 40-60 ng/mL levels
11
Vitamin D toxicity rare below 10,000 IU/day chronic
12
100,000 IU bolus raises levels by 20 ng/mL acutely
13
D3 superior to D2; 1.7x potency in raising levels
14
Bariatric patients need 3,000-6,000 IU/day
15
Pregnancy RDA: 15 mcg (600 IU), but 4,000 IU recommended
16
Children 1-13 years: 15 mcg (600 IU) RDA
17
>10,000 IU/day risks hypercalciuria in 10%
18
Co-supplement with K2 for calcium balance at high doses
19
50 mcg (2,000 IU) daily safe for breastfed infants
20
6,000 IU/day for 10 weeks normalizes 95% deficient patients
21
Serum levels plateau at 50-80 ng/mL with 5,000 IU daily
22
Single 600,000 IU dose elevates by 30 ng/mL for 3 months
23
Plant D2 less bioavailable; half-life shorter than D3
24
Malabsorption syndromes require 10,000 IU/day maintenance
25
Lactation: 25 mcg (1,000 IU) recommended daily
26
Teens 14-18: 15 mcg (600 IU) RDA
27
Toxicity symptoms at >150 ng/mL in 1-2% high-dose users
28
Magnesium needed for activation; deficiency blunts effects
29
1,000 IU raises levels by 5-10 ng/mL steady-state
Interpretation
Supplementation Data Interpretation
In supplementation, modest daily dosing like 800 IU can lift deficient adults by about 10 to 20 ng/mL while many cases can also be corrected faster with 50,000 IU weekly for 8 weeks, and the 4,000 IU daily upper limit helps frame how far intake should be pushed.
report visual · Key figures
Vitamin D deficiency is widespread—especially in high-risk groups
Across populations, vitamin D deficiency affects a large share of people, with higher prevalence in specific groups (e.g., nursing home residents, pregnant women, and certain regions).
1
Globally, 1 billion people have vitamin D deficiency (<20 ng/mL)
35%
In the US, 35% of adults have serum 25(OH)D <20 ng/mL indicating deficiency
79.4%
Pregnant women worldwide: 79.4% prevalence of 25(OH)D <20 ng/mL
74%
Nursing home residents have 74% prevalence of severe deficiency (<12 ng/mL)
80%
Middle East/N Africa: >80% prevalence <20 ng/mL
-100%
In India, 70-100% of population shows vitamin D deficiency (<20 ng/L)
Reference
Cite This Report
This report is designed to be cited. We maintain stable URLs and versioned verification dates. Copy the format appropriate for your publication below.
APA
Ryan Townsend. (2026, February 13). Vitamin D Statistics. Gitnux. https://gitnux.org/vitamin-d-statistics
MLA
Ryan Townsend. "Vitamin D Statistics." Gitnux, 13 Feb 2026, https://gitnux.org/vitamin-d-statistics.
Chicago
Ryan Townsend. 2026. "Vitamin D Statistics." Gitnux. https://gitnux.org/vitamin-d-statistics.
Sources & references
11 datasets cited across this report · attribution is report-level