Vitamin D (1994-2017) & Flu


Learn more about preventing colds and flu.


The researchers noted that influenza and similar illnesses have a strong seasonal association and that the role of vitamin is widely accepted to be important in defending against flu.

They investigated how UV radiation and vitamin D can affect such illness. They compared how the body's immune system, through its molecular and cellular structure acts on pathogens and the process of immunity.

Both UV radiation and vitamin D have an effect on creating antimicrobial agents in the body (peptides) and how they affect the ability of the immune system to adapt to new pathogens.

They found that vitamin D has a larger effect compared to UV radiation. This is because it modulates the response of the body through a wide range of tissues.

Researchers: Abhimanyu, A.K. Coussens
Published: The role of UV radiation and vitamin D in the seasonality and outcomes of infectious disease, Photochemical and Photobiological Sciences, January, 2017.


Vitamin D has a strong capacity to strengthen the immune system and resistance to influenza by preventing the release to too-large amounts of the biochemicals that attract white blood cells to infectious locations in the body. Staying indoors too much lowers vitamin D levels so vitamin D supplementation is more important in the winter and for those who spend much time indoors.

Researchers: B. Acharya, K. Thapa
Published: Journal of Napal Research Council, January 2016

2011 - D boosts the immune response

In this study the researchers wanted to know whether Vitamin D helped boost the bodies' immune response. In the lab, they found that gingival cells that were treated with Vitamin D displayed an improved ability to produce an endogenous antibiotic that was able to kill more bacteria than untreated cells.

Researchers: L. McMahon, K. Schwartz, O. Yilmaz, E. Brown, L. K. Ryan, G. Diamond.

Published: Vitamin D-Mediated Induction of Innate Immunity in Gingival Epithelial Cells. Infection and Immunity, 2011


Researchers investigated the relationship between vitamin D levels in the body and respiratory tract infections and the role of vitamin D in preventing illness.

Vitamin D supports general immune system health by increasing production of anti-microbial peptides which are biochemicals found within different kinds of white blood cells and keratinocytes. Vitamin D supports the ability of the immune system to adapt to invading microbes, and helps to maintain the balance of T-helper cells. T-helper cells are an essential part of the immune system and its adaptive response. They stimulate production of antibodies to fight illness.

It's easily noticed that sickness is more common in the winter when there is less sunlight and the body creates less vitamin D naturally. Researchers evaluating health of almost 19,000 children and adults found higher levels of vitamin D in the body are associated with lower rates of respiratory tract infections.

They found that 24% of patients with low vitamin D levels (25-OHD levels) had recent respiratory tract infections while only 17% of patients with high vitamin D levels had respiratory tract infections.

The researchers commented on a number of other studies which marked an association between higher levels of vitamin D consumption with lower rates of respiratory tract infections. These included in young Finnish solders (Laaski,2007), children (Linday, 2004 and Rehman, 1994), postmenopausal women (Aloia, 2007). They also noted that patients with tuberculosis had low vitamin D levels (iu, 2006).

The full article is here.

Researchers: A.A. Ginde, J.M. Mansbach, et al,
Published: Association between serum 25-hydroxyvitamin D level and upper respiratory tract infection in the Third National Health and Nutrition Examination Survey, Archives of Internal Medicine, February, 2009