What is Vitamin D: symptoms and consequences of a deficiency.

Vitamin D

Vitamin D is a fat-soluble vitamin that is essential for our body. It is known for its ability to keep bones healthy but it is also beneficial for the brain and heart. But what happens in case of deficiency? What symptoms can appear?

There are two main forms of this vitamin: D2 known as ergocalciferol and D3 known as cholecalciferol.

Most of the vitamin D needed by the body is obtained from exposure to the sun, but it is also present in some foods and food supplements; vitamin D obtained from these sources is biologically inert and must be hydroxylation in the body to provide functional use.


The primary role of vitamin D is to support the absorption of calcium from dietary sources in the blood and prevent calcium reabsorption in the kidneys. This effect helps direct calcium to osteoclasts and osteoblasts to strengthen bones, as well as to reduce the risk of hypocalcaemic tetany associated with high calcium intake.

Vitamin D deficiency

When there is an inadequate level of this vitamin in the body the effects tend to appear in the long term, in particular causing thinning and brittleness in the bones. As a result, it can cause rickets in children, as well as osteomalacia and osteoporosis in adults.

Consequences that may appear include:

  • Rickets: one of the most serious and known consequences of vitamin D deficiency in children is rickets. It can occur due to adequate exposure to sunlight and/or poor dietary intake. It is important that women during pregnancy and lactation have adequate levels of vitamin D to protect the child. Vitamin D deficiency in adults can lead to deformation of bones, abnormal bowing in the lower limbs and spine.
  • Depression: in Nordic countries where exposure to the sun is low for several months during the year, numerous cases of depression have been found, some particularly serious and linked to the risk of suicide. It is hypothesized that such conditions may also be linked to deficiency. In the Nordic countries, vitamin D3 supplements are taken to prevent depression this vitamin stimulates the production of serotonin, the hormone of happiness.
  • Autoimmune diseases: low levels of vitamin D could lead to a higher incidence of autoimmune diseases, such as rheumatoid arthritis, Lupus and type 1 diabetes.
  • Risk of Alzheimer’s disease: A study conducted in Scotland correlated vitamin D deficiency with the increased risk of Alzheimer’s disease, with particular reference to populations living in sunlit areas of the world.
  • Risks for the heart: an Italian study has shown that low levels of this vitamin can be dangerous for the health of the heart. According to researchers at the Ospedale Maggiore della Carità of the University of Eastern Piedmont, those lacking (levels below 20ng/mL) have a 32% higher risk of developing coronary artery disease (coronary artery disease).
  • Risk of multiple sclerosis for women: in a recent study, vitamin D deficiency has been associated with a doubled risk for women to develop multiple sclerosis, a neurodegenerative disease.

The most common cause of deficiency is lack of exposure to sunlight, which can be coupled with poor dietary sources. In particular: the elderly, full-time employees and people who cover their skin while outside or live in areas with little sunlight.

Direct sunlight is not recommended for the newborn baby’s skin and, therefore, most of the necessary vitamin D must be obtained from breast milk. This often leads to deficiency, although it depends on the mother’s level.

The effect of sunlight

When the ultraviolet rays of sunlight come into contact with human skin, 7-dehydrocholesterol reacts and starts producing vitamin D3.
The ideal wavelength of ultraviolet light is 295-297 nm, which most commonly occurs in tropical areas and during spring and summer in seasonal climates.

People living in areas that do not receive large amounts of ultraviolet light at this wavelength, such as in Arctic polar circles, are more likely to be at risk of vitamin deficiency.
People with darker, more toned skin require more sunlight to trigger vitamin D production and, as a result, are commonly affected by vitamin deficiency.

Despite the positive effect of sunlight on vitamin D production in the body, recommendations for increasing exposure to sunlight are given with caution because of the risk of skin cancer.
Sunscreen inhibits the effects of sunlight on the skin, thus offering protection from harmful ultraviolet rays, but also limiting vitamin D production.

Ideally, short periods of sun exposure of 10-15 minutes with direct contact with face and arms are recommended. However, skin protection is necessary for longer periods of time and appropriate sun safety practices should always be followed.
Everyone should, however, try to spend more time outdoors to promote their own well-being.
Vitamin D regulates calcium metabolism and is essential for the nervous system and the heart.

Dietary sources

As far as nutrition is concerned, sources of vitamin D can be either of animal origin, such as eggs, milk and derivatives, or of vegetable origin, with particular reference to mushrooms.
A balanced diet and sun exposure should ensure adequate levels of vitamin D.
Vitamin D supplements are recommended when people are at risk of deficiency or have low levels of vitamin D.

Vitamin D Rich Food

But how can we recognise the symptoms of vitamin D deficiency and what are the consequences?

Symptoms of deficiency

In case of deficiency we may be confronted with different types of symptoms:

  • Bone pain and muscle weakness: these are symptoms that can be confused with those of a trivial flu as well as another long series of health problems.
  • Osteoporosis: a deficiency exposes you to a greater risk of suffering from osteoporosis.
  • Heart problems.
  • Asthma in children: especially if they spend a lot of time at home.
  • Cognitive disorders: especially the elderly, who are often deficient in this vitamin, may experience problems in the cognitive sphere.
  • Psychological and emotional disorders: a deficiency can lead to mood swings and unmotivated sadness.
  • Hand sweating: when this symptom appears in a seemingly inexplicable way it is often associated with vitamin D deficiency, as it would be one of the most frequent alarm bells of this deficiency.