Vitamin D3

The Science

Vitamin D3

Vitamin D3, or cholecalciferol, is a fat-soluble vitamin well known for its role in supporting bone health and a healthy immune system. Vitamin D3 activates key peptides in the body that influence immune cell activity, which promotes strong immune responses that help to defend against invading threats. According to Dr Jim Bartley, “Low vitamin D levels are associated with an increased incidence of upper respiratory tract infections.”

Vitamin D

Occurrence in Food & Supplements

“Vitamin D is found in only a few foodstuffs, with fatty fish and fish oils, liver, milk and eggs being the main natural sources… Both vitamin D2 and vitamin D3 are used in food supplements, at levels up to 0.0125mg per daily dose.” (EVM 2003)

Absorption & Bioavailability

“Vitamin D is absorbed from the small intestine as bile salt-dependent micelles and circulated in the body via the lymph… Small amounts of 25-hydroxyvitamin D are found in meat and breast milk.” (EVM 2003) (EVM 2003)

Safe Daily Level

“For guidance purposes only, a level of 0.025mg/day [25μg/day] supplementary vitamin D would not be expected to cause adverse effects in the general population.” (EVM 2003)

Vitamin D Health Benefits

Vitamin D…

  • contributes to the normal function of the immune system.
  • contributes to normal blood calcium levels.
  • contributes to the maintenance of normal muscle function.
  • contributes to the maintenance of normal bones.
  • contributes to the maintenance of normal teeth.
  • has a role in the process of cell division.
  • is needed for normal growth and development of bone in children.
  • contributes to the normal function of the immune system in children.
  • helps to reduce the risk of falling associated with postural instability and muscle weakness. Falling is a risk factor for bone fractures among men and women 60 years of age and older.

Further Information

Vitamin D

People tend to catch more colds, flu and viruses (and get sicker from them) in the dark winter months when we get very little sunshine. Our bodies make vitamin D when sunlight acts upon our skin, so we struggle to make enough in winter, which explains why there is a surge in respiratory illnesses, hospitalisations and deaths at that time of year.

  • The National Health Service (NHS) recommends vitamin D supplements, even during “spring and summer”.
  • Fox News  reported “Studies reveal nine out of 10 COVID-19 deaths could have been prevented if people had adequate Vitamin D levels.”

Boost Immunity With Vitamin D3

Vitamin D3 plays an important role in supporting your body’s natural immune function. D3 activates specific peptides in the immune system that help to defend against external threats. These peptides stimulate immune cell activity, which promotes strong immune responses.

Reduced vitamin D3 levels can adversely affect your immune cells’ ability to protect your body against invasive environmental threats. For T cells and other immune cells to function properly, they must first encounter an external threat. When this occurs, the T cells seek out vitamin D3, and if they can’t find it, it can’t be activated and can’t be mobilised to protect you.

Your innate immune system also benefits from sustained vitamin D3 levels because it encourages the purifying properties of macrophages (innate immune cells). The macrophages identify and protect against environmental threats and also activate T cells. Macrophages also activate cleansing peptides, which break down toxins so they can be easily removed from the body.

Scientific References

“Vitamin D is involved in the production of antimicrobial peptides that provide a natural defence against potential microbiological pathogens. Vitamin D supplementation increases [peptide] production. Low vitamin D levels are associated with an increased incidence of upper respiratory tract infections.”

Bartley, J. (2010). Vitamin D, innate immunity and upper respiratory tract infection. The Journal of Laryngology & Otology, 124(5), 465-469. doi:10.1017/S0022215109992684

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“Observations suggest that vitamin D is a key factor linking innate and adaptive immunity, and both of these functions may be compromised under conditions of vitamin D insufficiency.”

Hewison, M. (2012). Vitamin D and immune function: An overview. Proceedings of the Nutrition Society, 71(1), 50-61. doi:10.1017/S0029665111001650

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“[Vitamin D3] can potently inhibit pathogenic T cells and gives rise to elevated numbers of regulatory T cells.”
Baeke, F., Etten, E., Overbergh, L., & Mathieu, C. (2007). Vitamin D3 and the immune system: Maintaining the balance in health and disease. Nutrition Research Reviews, 20(1), 106-118. doi:10.1017/S0954422407742713

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