Vitamin D is also called the "sunshine vitamin" because it is produced in the skin in response to exposure to sunlight. In fact, the body naturally produces vitamin D.

Certain foods also contain it, as well as supplements that are used when blood levels are not adequate.

But why is Vitamin D so important? Let's clarify what vitamin D is used for.

Vitamin D has several important functions.

The most important is to regulate the absorption of calcium and phosphorus and facilitate the function of the immune system.

In fact, a sufficient amount of vitamin D is important for the normal growth and development of bones and teeth, as well as for improving resistance to certain diseases.

Let's see in detail the properties of Vitamin D.

1. Vitamin D fights disease

Scientific literature shows that vitamin D can:

  • reduce the risk of multiple sclerosis, according to a 2006 study in the Journal of the American Medical Association
  • decreasing the chances of developing heart disease helps reduce the likelihood of developing the flu
  • A recent study investigated the preventive effect of vitamin D against interstitial pneumonia. Published results stated that vitamin D3 is activated locally in lung tissues, suggesting that a high dietary intake of vitamin D3 may have a preventive effect against interstitial pneumonia.

2. Vitamin D reduces depression

Research has shown that vitamin D could play an important role in regulating mood and preventing depression. In a scientific study, scientists found that people with depression who received vitamin D supplements noticed an improvement in their symptoms.

3. Vitamin D prevents the onset of heart disease

In another study, overweight subjects who took a vitamin D dietary supplement improved their risk indicators for developing heart disease.

4. Vitamin D and intestines

It has been observed that the ability of vitamin D to modulate the activity of the immune system in the intestine can influence the composition of the microbiome. The researchers noted an inverse association between the levels of the vitamin and the concentration of two proteins ((E-selectin and C-reactive protein), involved in the inflammation process, which could therefore indicate an anti-inflammatory action of vitamin D.


Many factors can affect your ability to get sufficient amounts of vitamin D through the sun alone. These factors include:

  • Excessive use of sunscreen
  • Spending a lot of time indoors
  • Living in big cities where buildings block sunlight
  • Having darker skin. (The higher the melanin levels, the less vitamin D the skin can absorb.)

These factors contribute to vitamin D deficiency in an increasing number of people. That's why it's important to get some of your vitamin D from other sources besides sunlight.

Symptom of a vitamin D deficiency in adults:

  • tiredness, aches and general not feeling well
  • severe bone or muscle pain or weakness.

Doctors can diagnose hypovitaminosis by doing blood tests.

Vitamin D in food

Few foods contain vitamin D. For this reason, some foods are fortified, meaning vitamin D is added during their production.

So where is vitamin D found? The foods that contain it are:

  • salmon
  • sardines
  • egg yolk
  • shrimps
  • milk (fortified)
  • cereals (fortified)
  • yogurt (fortified)

It should be noted that any supplementation of vitamin D is always to be carried out only if recommended by your doctor.


  • Suzanne Judd and Vin Tangpricha “Vitamin D Deficiency and Risk for Cardiovascular Disease” - Circulation. 2008
  • Urashima M et al. " Randomized trial of vitamin D supplementation to prevent seasonal influenza A in schoolchildren. " - Am J Clin Nutr. 2010
  • Kassandra L. Munger, et al “Serum 25-Hydroxyvitamin D Levels and Risk of Multiple Sclerosis” - JAMA. 2006
  • R. Jorde "Effects of vitamin D supplementation on symptoms of depression in overweight and obese subjects: randomized double blind trial" - Jim 2008
  • Tsujino et al. "Pulmonary activation of vitamin D3 and preventive effect against interstitial pneumonia." - Journal of Clinical Biochemistry and Nutrition, 2019
See the author's articles
Dr.ssa Marina Putzolu

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