Vitamin D is vital for the human body because it helps the absorption of calcium and phosphorus by the intestines. Without it, the organism cannot absorb calcium which makes vitamin D so important in maintaining healthy bones. It plays a key role for the immune system, proper muscle function, and brain cell development. It also modulates the inflammatory responses of the body.
What are the main sources of vitamin D?
There are two ways our bodies naturally obtain vitamin D – through sunlight and through food.
The main foods rich in vitamin D are:
· Fish (salmon, mackerel, sardines, herring)
· Egg yolk
· Some types of milk and breakfast cereals fortified with vitamin D
Nevertheless, the main way the human body obtains this vitamin is not through food, but through exposure to sunlight. This property gives it the popular name “the sunshine vitamin”. When exposed to direct sunlight, the skin produces vitamin D (calciferol) and after that, it is stored in the body to be used later when we may not have access to sunlight.
There are many factors that can affect how much vitamin D is produced by the skin, including the season, latitude, and skin pigmentation. Depending on where you live during the winter months, vitamin D production may slow down or be completely absent.
People who do not get enough exposure to sunlight and those who are over 65 years old are at a higher risk of vitamin D deficiency.
How is vitamin D produced?
Vitamin D is a collective term for the compounds vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). Once in the body, vitamin D is transported to the liver where it picks up additional oxygen and hydrogen molecules and gets converted to 25-hydroxyvitamin D, or 25(OH)D. It is precisely the concentration of 25-hydroxyvitamin D in the blood (including D2 and D3) that is considered the best indicator of vitamin D status. This is the substance that can be tested using a blood test to confirm or rule out potential vitamin D deficiency.
What are the risks of vitamin D deficiency?
The health risks associated with vitamin D deficiency are much more severe than previously thought. Vitamin D deficiency has been linked to some serious diseases such as osteoporosis, osteomalacia, multiple sclerosis, cardiovascular disease, pregnancy complications, diabetes, depression, stroke, autoimmune diseases, influenza, various types of cancer, infectious diseases, Alzheimer’s disease, obesity, high mortality, etc.
Vitamin D deficiency symptoms are often too subtle and difficult to recognize which makes it challenging to diagnose.
The main symptoms in adults include:
· Fatigue
· Bone pain
· Muscle pain or weakness
· Mood changes or depression
Children with a mild form of vitamin D deficiency may experience muscle weakness or pain. However, when there is a severe lack of vitamin D, the risk of rickets increases. In this case, symptoms may include abnormal growth due to bone deformity, muscle weakness, bone pain, and joint deformity.