

A human body produces vitamin D as a response to sun exposure. A person can also boost their vitamin D intake through certain foods or supplements.





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During sun exposure, a person’s body produces vitamin D.


  • promoting healthy bones and teeth
  • supporting immune, brain, and nervous system health
  • regulating insulin levels and supporting diabetes management
  • supporting lung function and cardiovascular health
  • influencing the expression of genes involved in cancer development

Read on to find out about these roles in more detail:

1. Healthy bones






2. Reduced risk of flu




3. Healthy infants





Furthermore, vitamin D may enhance the anti-inflammatory effects of glucocorticoids. This benefit makes it potentially useful as a supportive therapy for people with steroid resistant asthma.

4. Healthy pregnancy




Although the body can create vitamin D, a deficiency can occur for many reasons.


Skin type: Darker skin, for example, and sunscreen, reduce the body’s ability to absorb the ultraviolet radiation B (UVB) rays from the sun. Absorbing sunlight is essential for the skin to produce vitamin D.

Sunscreen: A sunscreen with a sun protection factor (SPF) of 30 can reduce the body’s ability to synthesize the vitamin by 95% or more. Covering the skin with clothing can inhibit vitamin D production also.

Geographical location: People who live in northern latitudes or areas of high pollution, work night shifts, or are homebound should aim to consume vitamin D from food sources whenever possible.

Breastfeeding: Infants who exclusively breastfeed need a vitamin D supplement, especially if they have dark skin or have minimal sun exposure. The American Academy of Pediatrics recommend that all breastfed infants receive 400 international units (IU) per day of oral vitamin D.

Supplement drops for babies are available online.

Although people can take vitamin D supplements, it is best to obtain any vitamins or minerals through natural sources wherever possible.

Read more on vitamin D deficiency.


Symptoms of vitamin D deficiency may include:

If Vitamin D deficiency continues for long periods, it may result in complications, such as:

  • cardiovascular conditions
  • autoimmune problems
  • neurological diseases
  • infections
  • pregnancy complications
  • certain cancers, especially breast, prostate, and colon.

Getting sufficient sunlight is the best way to help the body produce enough vitamin D. Plentiful food sources of vitamin D include:

  • fatty fish, such as salmon, mackerel, and tuna
  • egg yolks
  • cheese
  • beef liver
  • mushrooms
  • fortified milk
  • fortified cereals and juices

Here, learn how to get more vitamin D from the sun.

People can measure vitamin D intake in micrograms (mcg) or international units (IU). One microgram of vitamin D is equal to 40 IU.

The recommended daily intakes of vitamin D are as follows:

  • 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).

Sensible sun exposure on bare skin for 5–10 minutes, 2–3 times per week, allows most people to produce sufficient vitamin D. However, vitamin D breaks down quite quickly, meaning that stores can run low, especially in winter.

The upper limit that healthcare professionals recommend for vitamin D is 4,000 IU per day for an adult. However, the National Institutes of Health (NIH) say that vitamin D toxicity is unlikely at intakes under 10,000 IU per day.

Excessive consumption of vitamin D can lead to over calcification of bones and the hardening of blood vessels, kidney, lung, and heart tissues.

The most common symptoms of excessive vitamin D include headache and nausea. However, too much vitamin D can also lead to the following:

Excess vitamin D usually occurs from taking too many supplements. It is best to get vitamin D from natural sources.

If someone is taking supplements, they should choose their brand carefully, as the FDA do not monitor the safety or purity of supplements.

There is a selection of vitamin D supplements available for purchase online.

It is the total diet and eating pattern that is most important in disease prevention and good health. It is better to eat a diet with a variety of nutrients than to concentrate on one nutrient as the key to good health.