When it comes to making a decision about our diet, we usually have a number of questions. To take a step towards positive change, we need answers based on scientific evidence.
Vitamin D and the health of the human body

Why do we need vitamin D ?

Vitamin D3, also known as the 'sunshine vitamin,' provides multiple benefits throughout your body. Vitamin D3 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.

D3 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 D3 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 :

  • contributes to the normal absorption/utilization of calcium and phosphorus
  • contributes to normal blood calcium levels
  • contributes to the maintenance of the normal state of the bones
  • contributes to the maintenance of normal muscle function
  • contributes to the maintenance of the normal condition of the teeth
  • contributes to the normal functioning of the immune system
  • plays an important role in the process of cell division

Risk factors

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:

  • Babies and toddlers, as well as teenagers who spend little time playing outside.
  • Pregnant and lactating women.
  • People over 65 (the skin is less able to produce vitamin D as we age).
  • People with darker skin tones (Asians, Africans, Caribbean people of African descent, and people of Middle Eastern descent living in northern climates).
  • People who cover most of their body when outside.
  • People who live further north will be exposed to sunlight that is not strong enough to trigger vitamin D synthesis in the skin.
  • Those who spend very little time outside during the late spring and summer (housebound, shop or office workers, night shift workers, etc.).
  • People who live and work in areas with high levels of air pollution.


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.

Skin type


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 D3 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.  

Physical inactivity


In our muscles, the lack of vitamin D3 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 D3 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.  


Read the Vitamin D Test and ZinoShine+ brochures.



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