Why do we need vitamin D ?
Vitamin D, also known as the 'sunshine vitamin,' provides multiple benefits throughout your body. Vitamin D plays a key role in the body's immune response.
The vitamin D receptor is expressed on immune cells such as B cells, T cells, and antigen-presenting cells, and therefore vitamin D regulates both innate and adaptive immune responses. It should also be noted that vitamin D deficiency is directly related to increased risk of autoimmunity and increased vulnerability to infections. Therefore, vitamin D plays an important role in supporting the normal function of a healthy immune system, enhancing the pathogen-fighting ability of monocytes and macrophages (white blood cells that are a vital part of the defense) and drastically reducing inflammation. All of these help support the immune response and allow your immune system to proactively protect against acute respiratory infections and pneumonia.
Vitamin D is also highly valued for its role in supporting normal muscle and bone structure by enhancing calcium absorption in the small intestine. Through the bloodstream, vitamin D helps absorb calcium and phosphorus, which in turn help keep your bones healthy, reducing the risk of fractures and improving muscle strength. In addition, when there are sufficient levels of vitamin D in our diet, we increase the chances of achieving peak bone mass in adulthood, which helps prevent osteoporosis.
However, if your body doesn't have enough vitamin D available to absorb calcium effectively, it will pull calcium from your bones and weaken them. If this condition is not treated, it can potentially lead to fractures and osteoporosis.
According to the European Food Safety Authority, vitamin D :
Individual characteristics such as skin color, body weight and living conditions increase the risk of vitamin D deficiency. Different stages of life also have an impact. Below you will find the groups most at risk of low vitamin D levels.
Groups at risk of low vitamin D who may benefit from supplementation:
Older people tend to lose their appetite, reduce their intake of foods rich in vitamin D3, such as oily fish, and spend more time indoors compared to younger people. Also, the synthesis of vitamin D in the skin decreases with age.
People with dark skin need up to 6 times more sun exposure than those with light skin.
We get about 80% of our vitamin D from sun exposure. However, using sunscreen reduces the amount of sunlight reaching the skin and reduces the production of vitamin D on the skin.
Overweight and obesity
Research has shown that serum 25(OH)D is approximately 20% lower in obese individuals. One possible factor causing this thinning is increased body fat, but also because overweight people are more likely to wear clothing that covers their body, thus limiting skin exposure to the sun.
In our muscles, the lack of vitamin D is associated with decreased neuromuscular function, strength, gait speed, and balance. By increasing your daily levels of outdoor physical activity and exercise, you help combat these negative effects while creating more opportunities to activate vitamin D production from your own body.
In general, supplementation is recommended during the winter months for people living at latitudes of 35n and above. The skin is unable to produce vitamin D from October to March as the available sunlight is not strong enough.