Vitamin D is essential for the bones and teeth, the immune system, brain health, and for regulating inflammation. The body produces vitamin D as a response to sun exposure.
Certain foods and supplements can also boost vitamin D intake. Despite its name, vitamin D is not a vitamin but a hormone or prohormone.
In this article, we look at the benefits of vitamin D, what happens to the body when people do not get enough, and how to boost vitamin D intake.
Vitamin D plays a critical role in many bodily functions.
Healthy bones
Vitamin D
Vitamin D deficiency in children can cause rickets, leading to a bowlegged appearance due to the softening of the bones, and dental problems, such as teeth not forming as they should.
Similarly, in adults, vitamin D deficiency
Immune function
An adequate intake of vitamin D may support good immune function and reduce the risk of autoimmune diseases.
Although the body can create vitamin D from sunlight, some people develop deficiencies. Factors that can influence this include:
- Lack of sun exposure: People who live in northern climates or areas of
high pollution may not get as much vitamin D as others. Those who work night shifts or do not go outside can also develop a deficiency. - Skin color: Pigmentation in the skin reduces the body’s ability to absorb ultraviolet B (UVB) rays. Those with darker skin tones synthesize less vitamin D from sunlight than people with lighter skin.
- Age: The skin’s ability to synthesize vitamin D decreases with age. Older adults may also spend more time indoors.
- Breastfeeding: Babies cannot get enough vitamin D from breast milk on its own. The American Academy of Pediatrics recommends that exclusively and partially breastfed infants receive
400 international units (IU) per day of oral vitamin D until they are weaned. After weaning, they should get at least 1,000 mL/day vitamin D-fortified formula or whole milk. Children getting less than this, or who caregivers did not breastfeed, should take 400 IU vitamin D supplements. - Body weight: High levels of fat in the body can limit its ability to absorb vitamin D from the skin.
- Certain medical conditions: Vitamin D is fat soluble, meaning intake is dependent on the gut absorbing dietary fats. Conditions that limit fat absorption can decrease vitamin D intake from the diet.
- Gastric bypass surgery: This surgery bypasses a part of the upper intestine that absorbs large amounts of vitamin D. This bypass can cause a deficiency.
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- bone pain
- joint pain
- muscle weakness or spasms
- problems with bone development or the teeth
Over time, weakened bones may contribute to osteoporosis and increase the risk of falls and fractures, especially in older adults.
Vitamin D deficiency can also lead to hyperparathyroidism, which is when the parathyroid glands create a hormone imbalance that raises the blood calcium levels too high.
Infancy and childhood is a period of rapid growth bone growth. Due to this, it is essential for infants to get adequate amounts of vitamin D.
Chronic vitamin D deficiency
Vitamin D deficiency also has links to high blood pressure in children. A 2018 study found a possible connection between low vitamin D levels and arterial wall stiffness.
The American Academy of Allergy Asthma and Immunology (AAAAI) suggests a connection between low vitamin D exposure and an increased risk of allergic sensitization.
Children who live closer to the equator, where light levels are higher, have lower rates of admission to the hospital for allergies and fewer prescriptions for epinephrine auto-injectors, or EpiPens. They are also less likely to have a peanut allergy.
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Further resources
For more in-depth resources about vitamins, minerals, and supplements, visit our dedicated hub.
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The following foods provide some vitamin D, too:
- fatty fish, such as salmon, mackerel, and tuna
- egg yolks
- cheese
- beef liver
- mushrooms
- fortified milk
- fortified cereals and juices
People can measure vitamin D intake in micrograms (mcg) or international units (IU). One mcg of vitamin D is equal to 40 IU.
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| Demographic | Recommended daily intake |
|---|---|
| Infants 0-12 months | 400 IU (10 mcg) |
| Children 1-18 years | 600 IU (15 mcg) |
| Adults up to 70 years | 600 IU (15 mcg) |
| Adults over 70 years | 800 IU (20 mcg) |
| Pregnant or lactating women | 600 IU (15 mcg) |
The upper limit that healthcare professionals recommend for vitamin D is
Excessive vitamin D can lead to hypercalcemia, which may lead to fatigue, weakness, bone pain, and loss of appetite. More severe symptoms
- nausea or vomiting
- dehydration
- excessive thirst
- excessive urination
- kidney stones
- confusion
- apathy
In extreme cases, hypercalcemia can harden soft tissues, such as blood vessels, or lead to a coma. The condition
If someone is taking supplements, they should choose their brand carefully, as the Food and Drug Administration (FDA) does not monitor the safety or purity of supplements the same way it does pharmaceuticals.
Below are answers to some frequently asked questions about vitamin D.
What does vitamin D do for the body?
Vitamin D
What is the best source of vitamin D?
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How do I raise my vitamin D level quickly?
Spending a short amount of time in the sun, with some skin exposed, can raise vitamin D levels. It is important to protect the skin and eyes from the harmful effects of UV light when outside, though.
People can also take vitamin D supplements to raise their levels.
What is vitamin D the main cure for?
Vitamin D is a nutrient. It does not cure diseases on its own. However, it does support many bodily functions, so getting enough
The body produces vitamin D via sun exposure. Supplements and a
Research into the benefits of adequate vitamin D is still ongoing. A vitamin D deficiency can lead to weakened bones and osteoporosis. In excessive doses, vitamin D toxicity can cause hypercalcemia, which can be serious.